Patent Publication Number: US-2022218958-A1

Title: Device and Method for Single-Handed Access and Insertion of an Article

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to and claims priority to U.S. Provisional Patent Application Ser. No. 62/323,767, filed on Apr. 17, 2016, and U.S. Provisional Patent Application Ser. No. 62/447,037, filed on Jan. 17, 2017, the complete and entire disclosures of which are hereby expressly incorporated by reference herein. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO APPENDIX 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The inventions disclosed and taught herein relate generally to a device and method for the insertion of an article into a body using a single hand; and more specifically relate to the single-handed insertion of a guidewire or similar article or another elongated article such as, for instance, certain catheters into a targeted body space. In particular, the inventions disclosed herein relate to an apparatus that combines insertion of a substantially hollow piercing structure, such as a needle, a suction apparatus, and a guidewire, where the apparatus is configured to use with a single hand, and methods of using such apparatus. 
     The Seldinger technique is a ubiquitous maneuver in the field of medicine used to safely insert a cannula into a vessel, hollow organ, or body cavity. Examples of procedures and settings where it may be employed include arterial line placements, central venous catheter placements, angiograms, percutaneous tracheostomies, pleural catheter placement, percutaneous cholecystectomy, percutaneous nephrostomy, and percutaneous abscess drainage. With respect to vascular access, it is the current standard of care for placing a catheter, sheath, or cannula into a blood vessel during access procedures such as central venous catheter placement. In applying the Seldinger Technique, a physician first uses a needle to pierce through tissue to ultimately reach a targeted body space. A wire is then passed through the needle into the space. The wire secures a path into the space over which the needle may then be removed and additional instruments such as sheaths and catheters may be inserted into the space. 
     With respect to central venous catheter insertion and procedures targeting lumens with similarly low-pressure fluids like blood in the venous system, a syringe is coupled to the needle to apply suction. Once the physician gains access to the targeted body space, which is confirmed when a specific body fluid is aspirated into the syringe barrel, the physician holds the hub of the needle with one hand and uncouples the syringe with from the needle with the remaining hand. Once the uncoupling is complete, the physician inserts a guidewire through the lumen of the needle into the targeted body space in order to secure access. The physician then removes the needle, nicks the skin with a scalpel, and passes a dilator over the guidewire to dilate the tissue around the guidewire in order to facilitate catheter, sheath, or cannula insertion. Once the dilator is withdrawn, the physician passes the catheter, sheath, or cannula over the guidewire, leaving the catheter, sheath, or cannula in place. 
     Complications are known to occur as a result of the Seldinger Technique. Regarding central venous catheters, such complications include arterial puncture, hematoma, air embolism, pneumothorax, infection, and traumatic nerve injury. Long-term complications include venous thrombosis, the formation of arteriovenous fistula, and pseudoaneurysms. Penetration of the posterior vessel wall during insertion has been thought to be a leading factor in ongoing mechanical central venous access complications. This may occur due to the speed and angle of needle insertion. Loss of needle access into the target lumen as a result of penetrating the posterior wall or other lapse in technique can ultimately result in trauma to the surrounding tissue or structures, especially if the operator continues with wire insertion and other procedural steps such as dilation, or has to repeat the procedure. 
     Central venous access complications are also attributed to other factors, including errors in sterile technique, the time taken to achieve access, and the number of needle passes through the skin and central vessels. Studies have suggested that the morbidity risk of central line procedures increases with the time needed to place the device, as well as the number of attempts to cannulate the vein. In addition, data suggest that the training and experience of the clinician may have an effect on patient complication rates. 
     The use of ultrasound guidance during placement of a catheter, sheath, or cannula is well-documented to reduce rates of complications in central venous catheter placement. The precise identification of vessel anatomy and visualization of the puncture site that is enabled through the use of ultrasound has contributed to lowering the morbidity of vascular access, making ultrasound guidance standard clinical practice. Ultrasound guidance also allows the clinician to visually locate the needle tip relative to patient anatomy in real time. 
     The ultrasound-guided modified Seldinger Technique is implemented in a manner largely similar to the Seldinger Technique in many respects. During the needle insertion step, the physician uses the syringe with a needle in one hand—typically the operator&#39;s dominant hand—and an ultrasound probe in the other hand in order to visualize the needle&#39;s trajectory and location inside the patient&#39;s body using alternating longitudinal and cross-sectional views with the ultrasound probe. Like with the Seldinger Technique, once the operator gains access to the targeted body space, which is confirmed when a specific body fluid is aspirated into the syringe&#39;s barrel, the operator holds the needle&#39;s hub with one hand and uncouples the syringe from the needle with the remaining hand. During this step, the ultrasound probe must be placed down resulting in loss of visualization of the needle in the targeted space. The removal of the ultrasound probe from the patient also releases the pressure of the probe on the tissue, resulting in a detrimental movement of tissue relative to the needle tip, thereby directly increasing risk of potential injury and losing access. 
     Because the ultrasound-guided modified Seldinger Technique (and the standard Seldinger Technique) requires the use of two hands to uncouple the needle from the syringe, stabilize the needle, and insert the guidewire into the targeted body space after the initial needle insertion step, there is a period of time during the procedure in which a sharp needle is located inside of a patient&#39;s body while the physician or other clinician cannot visualize it and has limited control over it. In particular, once the needle tip is inside the targeted body space the clinician must drop the ultrasound probe and perform hand switching motions that can uncontrollably move the needle. The clinician must also uncouple the syringe from the needle in a step that can also move the needle and reduce needle control. The clinician must also pass a guidewire through the needle&#39;s lumen in a process that can also move the needle relative to the targeted body space. The clinician must pass the guidewire without seeing the wire trajectory and location of the wire tip in real time. While ultrasound guidance helps with initial needle location and access, its advantages may be lost during the multiple steps requiring the use of both of an operator&#39;s hands. It may be used for verification after these steps, but at this point needle access may already be lost, with other structures entered and possibly traumatized. The wire could also be threaded into other, non-target tissues, such as the incorrect vessel, or could be kinked or become stuck in the patient. The process then must be repeated from the beginning leading to the additional time and needle punctures known to be associated with morbidity. Thus, despite the advantages of ultrasound guidance in its current form, adverse events continue to occur. 
     Although the Seldinger Technique is described here in the common setting of central venous access, it is important to recognize that the same principles apply to cannula insertion into other body spaces using the Seldinger Technique including the use of ultrasound. Other surrounding organs and structures may also be damaged secondary to needle and guidewire malposition. Abdominal procedures such as percutaneous nephrostomy and cholecystectomy, for example, may be complicated by bowel or vascular injury. The invention described herein may similarly be applied in other settings where the Seldinger Technique is used, especially but not exclusively with ultrasound. Needle, wire, and catheter sizes used during these procedures may vary for different target organs and objectives; however, the invention may be adapted using industry standard interlocking systems for different components or by specific design parameters applied to the inventions disclosed herein. It will be understood that each of the inventions disclosed herein, even where described in the context of central venous access, are equally and directly applicable to other body access procedures included, but not limited to, arterial line placements, angiograms, percutaneous tracheostomies, pleural catheter placement, percutaneous cholecystectomy, percutaneous nephrostomy, and percutaneous abscess drainage. 
     Description of the Related Art 
     A number of access devices are known. For example, U.S. Pat. No. 8,915,884 discloses an access device that places a medical article within a body space of a patient. The device has a needle section that includes an elongated body and a needle hub. The device further includes a dilator portion that has a dilator and a dilator hub. The dilator is coaxially disposed and slideable over the elongated body of the needle section. The sheath is coaxially disposed and slideable over the dilator. The device further includes a first locking mechanism operably disposed between the needle hub and the dilator hub to inhibit at least unintentional axial movement between the needle section and the dilator portion and a second locking mechanism operably disposed between the dilator hub and the sheath hub to inhibit at least unintentional axial movement between the dilator portion and the sheath section. 
     As another example, U.S. Patent Application Publication No. 2015/0224267 discloses a safety needle system operable with a medical device includes: a housing with a needle mount having a needle; and a sheath telescopically engaged with the housing and surrounding the needle such that the sheath operates in a retracted position, in which the sheath exposes the needle, and an extended position, in which the sheath surrounds the needle. The sheath is coupleable to the medical device such that removal of the needle from the medical device draws the sheath over the needle, transitioning the sheath from the retracted position to the extended position. In one embodiment, the system includes a slider engaged with the sheath and/or housing and including a restraint that engages and disengages the sheath to respectively reinforce and weaken the coupling of the sheath and medical device. In another embodiment, the sheath includes a longitudinal track that slidingly engages a setting of the housing between sheath positions. 
     However, the operation of these inventions particularly for guidewire insertion requires the use of two hands. Where two hands are required for operation of procedures, any ultrasound visualization will necessarily be lost during the procedure. Therefore, it is apparent for the above that there is an ongoing need for new instruments, particularly instruments designed for single-handed operation for the placement of articles, such as guidewires, into veins, arteries, vessels, body cavities, and drainage sites of patients during access procedures. 
     The inventions disclosed and taught herein are directed to an improved apparatus and method for accessing a space in a body and inserting an article into that space. More particularly, the inventions disclosed herein allow for single-handed access into a body space, confirmation of access such as through application of suction, and securing access such as by guidewire insertion. This single-handed operation feature allows the operator to retain ultrasound visibility and stability while the guidewire is inserted, which, in turn, allows the operator to verify that the guidewire is going into the correct body space and that the needle does not move out of the targeted body space after achieving initial needle insertion. The apparatus may optionally also incorporate a protective sheath that can be used to shield the patient&#39;s anatomical structures from the needle tip immediately after initial needle insertion is obtained. Moreover, when the apparatus is equipped with a sheath, the sheath partially secures access and facilitates guidewire insertion. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly summarized, embodiments of the present invention are directed to an insertion apparatus for insertion of an article into a body. More particularly, the embodiments of the insertion apparatus of the present invention are directed to inserting a guidewire or similar article into a targeted body space of a patient. Such a targeted body space may commonly be a vein and the article for inserting into the targeted body space a guidewire. The insertion apparatus combines needle insertion, suction application through the needle, and guidewire insertion into a single device that is operable using a single hand. The insertion apparatus may optionally also include a sheath movably attached to the housing and configured to be able to be selectively advanced to cover the distal end of the needle. The sheath may be detachable from the housing and the needle removed from it to maintain a port into the targeted body space. 
     In some various embodiments of the invention, the insertion device comprises a housing, a piercing structure with a lumen, wherein the piercing structure extends distally from the housing, a vacuum chamber that communicates with the lumen of the piercing structure, and a guidewire, wherein the insertion device is configured to be operated with a single hand. The insertion device is configured to permit the piercing structure to be inserted into the body, while suction is applied through the lumen of the needle. When the targeted body space has been reached, the insertion device is configured such that the guidewire can be advanced into the targeted body space using the single hand of the user. 
     In use, the housing of the insertion device is gripped with a single hand of the user. The distal end of the piercing structure is inserted into the patient. Simultaneously, the user applies suction using a suction apparatus to confirm the targeted body space of the patient has been accessed. For instance, confirmation of piercing structure access to the lumen of a vein of the patient would be confirmed by the return of venous blood through the piercing structure lumen and/or visual ultrasound confirmation of needle tip location. Once placement of the piercing structure in the targeted body space is confirmed, the user advances the guidewire into the targeted body space using the single hand and can watch the wire trajectory in real time via ultrasound. 
     In some embodiments of the insertion apparatus, the housing includes grips configured to accommodate at least one finger of the user. In some embodiments of the insertion apparatus, a sheath is coaxially disposed about the piercing structure and is affixed to a sheath movement element that is movably affixed to the housing. The sheath can itself be removably or permanently affixed to the sheath movement element. In some embodiments, the vacuum chamber can be separate from the housing, or alternatively can be integrated with the housing. These and other features of embodiments of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of embodiments of the invention as set forth herein. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  illustrates a top perspective view of the insertion device in accordance with one embodiment. 
         FIG. 2  illustrates a bottom perspective view of the insertion device in accordance with the embodiment depicted in  FIG. 1 . 
         FIG. 3  illustrates a top perspective exploded view of the insertion device in accordance with the embodiment depicted in  FIG. 1 . 
         FIG. 4  illustrates a side cross-sectional view of the insertion to device in accordance with the embodiment depicted in  FIG. 1 . 
         FIG. 5  illustrates a top perspective view of the insertion device in accordance with another embodiment. 
         FIG. 6  illustrates a top perspective exploded view of the insertion device in accordance with the embodiment depicted in  FIG. 5 . 
         FIG. 7  illustrates a side cross-sectional view of the insertion device in accordance with the embodiment depicted in  FIG. 5 . 
         FIG. 8  illustrates a view of the embodiment depicted in  FIG. 5  as held by a clinician. 
         FIG. 9  illustrates a top perspective view of the insertion device in accordance with another embodiment. 
         FIG. 10  illustrates a top perspective exploded view of the insertion device in accordance with the embodiment depicted in  FIG. 9 . 
         FIG. 11  illustrates a detail perspective view of a portion of the embodiment depicted in  FIG. 9 . 
         FIG. 12  illustrates a cross-sectional view of the insertion device in accordance with the embodiment depicted in  FIG. 9 . 
         FIG. 13  illustrates a view of the embodiment depicted in  FIG. 9  as held by a clinician. 
         FIG. 14  illustrates a top perspective view of the insertion device in accordance with another embodiment. 
         FIG. 15  illustrates a top perspective exploded view of the insertion device in accordance with the embodiment depicted in  FIG. 14 . 
         FIG. 16  illustrates a side cross-sectional view of the insertion device in accordance with the embodiment depicted in  FIG. 14 . 
         FIG. 17  illustrates a view of the embodiment depicted in  FIG. 14  as held by a clinician. 
         FIG. 18  illustrates a view of the embodiment depicted in  FIG. 14  as held by a clinician using an alternative finger placement. 
         FIG. 19  illustrates a top perspective view of the insertion device in accordance with another embodiment. 
         FIG. 20  illustrates a top perspective exploded view of the insertion device in accordance with the embodiment depicted in  FIG. 19 . 
         FIG. 21  illustrates a side cross-sectional view of the insertion device in accordance with the embodiment depicted in  FIG. 19 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicants have invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer&#39;s ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer&#39;s efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. For clarity, it is to be understood that the word “proximal” refers to a direction relatively closer to a clinician using the device to be described herein, while the word “distal” refers to a direction relatively further from the clinician. For example, the end of a needle placed within the body of a patient is considered a distal end of the needle while the needle end remaining outside the body is a proximal end of the needle. Also, the words “includes,” “including,” “has,” and “having” as used herein, including the claims, shall have the same meaning as the word “comprising.” Also, the use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims. 
     Applicants have created an insertion device for inserting a guidewire or similar article into a targeted body space of a patient using a single hand. The targeted body space may commonly be a vein and the article for inserting into the targeted body space a guidewire. The insertion device combines needle insertion, suction application through the needle, and guidewire insertion into a single device that is operable using a single hand. The insertion device may optionally also include a sheath movably attached to the housing and configured to be able to be selectively advanced to cover the distal end of the needle. The sheath may be detachable from the housing to maintain a port into the targeted body space. 
     In some various embodiments of the invention, the insertion device comprises a housing, a piercing structure with a lumen, wherein the piercing structure extends distally from the housing, a vacuum chamber that communicates with the lumen of the piercing structure, and a guidewire, wherein the insertion device is configured to be operated with a single hand. The insertion device is configured to permit the piercing structure to be inserted into the body, while suction is applied through the lumen of the needle. When the targeted body space has been reached, the insertion device is configured such that the guidewire can be advanced into the targeted body space using the single hand of the user. 
     In use, the housing of the insertion device is gripped with a single hand of the user. The distal end of the piercing structure is inserted into the patient. Simultaneously, the user applies suction using a suction apparatus to confirm the targeted body space of the patient has been accessed. For instance, confirmation of piercing structure access to the lumen of a vein of the patient would be confirmed by the return of venous blood through the piercing structure lumen and/or visual ultrasound confirmation of needle tip location. Once placement of the piercing structure in the targeted body space is confirmed, the user advances the guidewire into the targeted body space using the single hand and can watch the wire trajectory in real time via ultrasound. 
     In some embodiments of the insertion apparatus, the housing includes grips configured to accommodate at least two fingers of the user. In some embodiments of the insertion apparatus, a sheath is coaxially disposed about the piercing structure and is affixed to a sheath movement element is movably affixed to the housing. The sheath can itself be permanently or removably affixed to the sheath movement element. In some embodiments, the vacuum chamber can be separate from the housing, or alternatively can be integral with the housing. 
       FIGS. 1-4  depict various details of the insertion apparatus (“insertion apparatus,” “insertion tool,” or “insertion device”), generally depicted at  10 , according to one embodiment. As shown, the insertion device includes a main housing  20 . Main housing  20 , for reference in the figures, has a top side  20 A and a bottom side  20 B. Main housing  20  may include handles,  21 A and  21 B, as depicted in this particular embodiment. Handles  21 A and  21 B are configured to facilitate a user gripping and operating the insertion device using one hand and aspirating body fluid, as will be described in further detail below. In this embodiment, handles  21 A and  21 B comprise both a full-loop and a half-loop finger grip on each side of main housing  20 . In alternative embodiments, the handles may comprise only half-loop or only full-loop finger grips, and may number one to four on either side or both sides of main housing  20 . In the present embodiment, main housing  20  is composed of a thermoplastic such as polycarbonate and is substantially transparent, although manufacture using other suitable materials will readily be apparent to a person of skill in the art. If main housing  20  is made using a substantially non-transparent material, such as a substantially translucent or substantially opaque thermoplastic, it may be desirable to include cut-out or window areas in housing  20  to permit a user to visualize needle hub  42  or vacuum chamber  50  during use as will be explained more fully below. 
     A hollow piercing structure, such as needle  40 , is affixed to a needle hub  42  at the proximal end  40 A of needle  40 . The proximal end  40 A of the needle  40  fits into a pocket in needle hub  37  and is fixed in place using an appropriate adhesive or other appropriate means as would be appreciated by a person of skill in the art. Needle  40  extends distally from needle hub  37  to distal end  40 B of the needle  40  where it terminates at a point or other sharp end suitable for piercing skin of a patient, such as bevel  41 . Needle hub  37  is configured to fit on the needle hub attachment  26  at the distal end of main housing  20 . The needle hub attachment  26  may or may not taper from the proximal end to the distal end, depending on the configuration of needle hub  37 . In this embodiment, needle hub attachment  26  is a male Luer-Lok connection fitting; needle hub  37  is a corresponding female Luer-Lok fitting. However, it will be understood that other appropriate fittings may be used, including friction fittings, to create a connection between needle hub  37  and needle hub attachment  26 . Appropriate fittings or other means of attaching the needle to the housing will create a connection that is substantially air-tight, as will be explained below. In some embodiments of the inventions, it may be desirable to provide an adjustable or removable connection between needle  40  and main housing  20  to permit the user to rotate needle  40  to adjust the orientation of needle bevel  41  relate to main housing  20 . It will also be appreciated that alternative embodiments of the inventions described herein need not require that needle  40  is removable, with a needle hub  37  or otherwise; indeed, alternative embodiments of the inventions described herein may include a needle  40  that is permanently attached to or otherwise an integral part of main housing  20 . Whether needle  40  is bonded to needle hub  37  or directly to main housing  20 , it is envisioned that a bond strength of at least about 3 in-lbs would be adequate for the practice of the inventions disclosed herein, recognizing that lower or higher needle bond strengths may be sufficient or even preferable depending on the specific application to which the embodiments of the inventions are used. 
     Insertion device  10  further includes a means to create a vacuum to provide a suction. Specifically, suction would be provided as a pressure differential between the distal end  40 B of needle  40  and the suction means. In to the present embodiment, the suction means is provided as a vacuum chamber  50  and a plunger  52 . As depicted in  FIGS. 1-4 , vacuum chamber  50  is shown as the barrel of a syringe. However, it will be apparent from this disclosure that vacuum chamber  50  need not be a syringe barrel that can be separated from main housing  20  as depicted in this embodiment. Alternatively, vacuum chamber  50  can be a portion of and contiguous with main housing  20 . In each embodiment, the volume of vacuum chamber  40  preferably is sufficient to provide for the aspiration of a volume of at least 4 milliliters of fluid, although a smaller volume could also be acceptable to practice the inventions disclosed herein. The distal end  52 B of plunger  52  includes a head  53  that creates a substantially air-tight annular seal against the wall of vacuum chamber  50 . In this embodiment, vacuum chamber  50  is depicted with nozzle  51  that fits substantially securely, by use of a friction fitting, into main housing  20  as shown. Alternative fittings, such as a male Luer-Lok fitting on the nozzle of vacuum chamber  50  and a female Luer-Lok fitting in main housing  20  would also be appropriate in this embodiment of insertion device  10 . The fitting of nozzle  51  to housing  20  makes a substantially air-tight seal between vacuum chamber  50  and lumen  35  in main housing  20 . Upon attachment of vacuum chamber  50  to main housing  20 , vacuum chamber  50  communicates with lumen  35 , which, in turn, communicates with the lumen of needle  40  from the distal opening  37  in housing  20  such that fluid can flow from distal end  40 B of needle  40 , through the needle lumen, through lumen  35 , through nozzle  51 , and into vacuum chamber  50 . In other words, lumen  35  serves as a conduit between the lumen of needle  40  and vacuum chamber  50 . The proximal plunger end  52 A can optionally be configured to include a grip (not shown in  FIGS. 1-4 ) such as a full or partial ring. The addition of a grip can be used by a clinician when drawing back plunger  52  with his or her thumb to create a vacuum in vacuum chamber  50 . 
     Insertion device  10  further includes a guidewire  60 . It is contemplated that insertion device  10  should be compatible with at least a 0.038-inch sized guidewire, although a person of skill in the art will appreciate that insertion device  10  may be designed to be specifically compatible with alternatively sized guidewires as may be necessary for a variety of procedures, practices, and applications. In this embodiment, guidewire  60  is disposed within guidewire housing  62 , and guidewire housing  62  is removably attached to main housing  20  at connector  68 . Guidewire housing  62  may be rigid or flexible, and is generally of sufficient length to hold the length of guidewire  50 . Further, guidewire housing  62  can be either removably or permanently attached to main housing  20 , or could be an integral part of main housing  20 . Guidewire housing  62  may additionally include a cap  63 . If present, cap  63  could serve a variety of purposes, including isolating guidewire  60  from the surrounding environment or to prevent guidewire  60  from being pushed out the proximal end of guidewire housing  62 . Main housing  20  is configured to allow the movement of guidewire  60  from the distal end of guidewire housing  62  at or about connector  68  along guidewire feed region  64  into lumen  36  of main housing  20 . Lumen  36  connects with lumen  35  in the main housing  20  at a point proximal to the connection of needle hub  37  to needle hub attachment  26 . Lumen  36  is configured to receive guidewire  60  at opening  27 . Lumen  36  is further configured to be fitted with a valve  28  between opening  27  and the point where lumen  36  joins with lumen  35 . Valve  28  is configured to allow the passage of guidewire  50  but to prevent the substantial flow of air that would substantially defeat a vacuum created by the proximal movement of plunger  52  in vacuum chamber  50 . It will be recognized by a person of skill in the art that while in this embodiment valve  28  is located at opening  27 , valve  28  could be placed at any location along lumen  36 . Moreover, it will be recognized by a person of skill in the art that a valve may not be necessary if guidewire  60  fits within lumen  36  tightly enough to prevent the substantial flow of air through lumen  36  such that the creation of a vacuum in vacuum chamber  50  is defeated. Furthermore, any variety or types of valves or other methods to maintain the pressure differential could be employed, as will be appreciated by a person of sill in the art. Such a valve or method could, for example, be pressure-sensitive. For purposes of the inventions described herein, the seal between guidewire  60  and the wall of lumen  36 , whether or not valve  28  is employed, should be able to maintain a pressure differential of at least about 300 mmHg, although the inventions described herein could be practiced if a pressure differential of less than 300 mmHg was maintained across lumen  36 . 
     In this embodiment, guidewire feed region  64  includes protrusion  65  between guidewire housing connector  68  and opening  27  to lumen  36 , over which guidewire  60  passes. Guidewire feed region  64  is generally configured to be accessible by the thumb of the user while gripping main housing  20  with one hand; however, the configuration may be altered in some embodiments of the present inventions such that the guidewire feed region  64  is accessible by a finger of the one hand of the user gripping main housing  20 . In this embodiment, the thumb of the user can be used to advance guidewire  50  through needle  40  toward distal end  40 B of needle  40  and into the targeted body space of the patient. Of course, the thumb of the user may also be used to move guidewire  50  in the opposite direction, toward proximal end  40 A of needle  40 , for instance if guidewire  50  needs to be retracted into the lumen of needle  40  and repositioned, or otherwise retracted from the targeted body space. Protrusion  65  can serve to provide tactile feedback to the clinician while advancing (or retracting) guidewire  60 , as well as to provide a raised surface to press against while advancing guidewire  60  to assist in the gripping of guidewire  60  to increase the efficiency of movement of guidewire  60 . It will be appreciated that protrusion  65  can be replaced with other suitable structures configured to assist a user in moving guidewire  60  along the guidewire feed region  64  in either a proximal or distal direction. Such suitable structures may include a pin and wheel arrangement, raised plate, partial sphere, or the like. Protrusion  65  may be aligned with an initial length marker on guidewire  60 , and compared to sequential markers on guidewire  60  to indicate the length of guidewire  60  that has been inserted into the patient. 
     In this embodiment, insertion device  10  includes a sheath  71  that is coaxially moveably disposed about needle  40 . Sheath  71  could optionally be echogenic to promote visualization via ultrasound. Sheath  71  is attached to sheath movement element  70  at sheath hub  74 . Sheath  71  may be permanently affixed to sheath movement element  70  at sheath hub  74  or may be removably attached, depending on the application and the specific use of the embodiment. Where sheath  71  is removably attached, sheath attachment would be configured so that sheath can be left in the tissue of the patient to provide a port through which the targeted tissue can be accessed. In this embodiment, sheath movement element  70  includes pusher  72 , spanning element  73 , sheath hub  74 , tab  75 , and groove connector  76 . Pusher  72  is configured to permit a user, while gripping main housing  20  with a single hand, to move sheath movement element  70  in proximal and distal directions using the thumb of the single hand. Movement of sheath movement element  70  in a distal direction would result in sheath  71  moving coaxially along needle  40  toward the needle distal end  40 B. Further, both the length of sheath  71  and the degree of movement permitted of sheath movement element  70  is sufficient to permit the furthest movement of sheath  71  in a distal direction to cover distal end  40 B of needle  40  to shield distal end  40 B of needle  40 . Conversely, movement of sheath movement element  70  in a distal direction would result in sheath  71  moving coaxially along needle  40  away from distal end  40 B of needle  40 . Continued movement of sheath movement element  70  would result in the exposure of needle distal end  40 B. Movement of the sheath movement element  70  in a distal direction from the position depicted in  FIG. 4  results in tab  75  of sheath movement element  70  passing over ridge  24  and resting in notch  23  of housing  20 . Notch  23  is created on the proximal end by ridge  24  and on the distal end by stopper  25 . The contact of tab  75  with stopper  25  arrests the distal advancement of sheath movement element  70 , and therefore the extent of movement of sheath  71  in the distal direction. In use, the passage of tab  75  over ridge  24  creates tactile feedback to inform the clinician that the furthest extent of sheath  60  advancement is being reached. In addition, when tab  75  is resting in notch  23 , proximal movement of sheath movement element  70  is partially restricted by ridge  24 , thereby reducing the possibility of accidental retraction of sheath  71 . Sheath movement element  70  is moveably attached to housing  20  by the joining of groove  78  of sheath movement element  70  to rail  38  of main housing  20  and by joining grooves  39 A and  39 B on the right and left sides of main housing  20 , respectively, to rails  76 A and  76 B, respectively, of sheath movement element  70 . Sheath movement element  70  may be configured to be removable from main housing  20  by a user if the sheath functionality is not desired for a particular application of the inventions. 
     In this embodiment of insertion device  10 , sheath movement tab  72  is disposed on the bottom  21 B of housing  20  and guidewire  50  is disposed on the top  21 A of housing  20 . However, it will be appreciated by persons of skill in the art that the inventions described herein can be practiced with both the sheath movement tab  72  and the guidewire  50  disposed on the same side of housing  20 . Examples of such embodiments are described in detail below. 
     For example,  FIGS. 5-7  depict an embodiment of the inventions described herein where the movement of a sheath and the movement of the guidewire are controlled by the user from the same side of the insertion device. One of the advantages of the inventions described herein, as previously explained, is to permit a clinician, or user, to insert a guidewire to secure access to a body space such as a vein using one hand. With the inventions disclosed herein, a clinician is able to puncture the body of a patient with a needle, confirm access to a targeted body space by aspirating fluid through that needle, and advance a guidewire to secure access into the targeted body space using a single hand. As explained herein, the ability to perform all of these activities with a single hand has numerous benefits for the clinician as well as the patient. To optimize the performance of all of these activities—piercing, confirming access, and securing access with a guidewire—the inventions described herein should allow the clinician to maintain hand position and function in an ergonomically beneficial manner. The consideration of human factors and ergonomics in the specific design and layout of the inventions described herein should allow for the insertion device to be maintained in an ergonomically-beneficial position such that the clinician is capable of puncturing the patient and advancing the needle of the invention device while aspirating fluid through the needle into the vacuum chamber of the insertion device. It will be apparent to a person of skill in the art that an additional ergonomic consideration is to permit the clinician to maintain fine control of the needle tip while aspirating fluid during insertion. It is also desirable that the clinician can clearly visualize the aspirated fluid while inserting the needle and simultaneous aspirating body fluid through the advancing or advanced needle. 
     While not necessary for the practice of the inventions described herein, it may be beneficial for the use of the insertion device that the guidewire be staged, or pre-loaded, in the needle during insertion of the needle into the patient so that the guidewire can be advanced into the targeted body space quickly after access to the targeted body space has been confirmed. Alternatively, it may be beneficial to preload the guidewire into the housing conduit distal to the valve but proximal to the needle lumen. It may be beneficial in some embodiments of the inventions disclosed herein that the insertion device has the ability to store some length of guidewire that may be required during the access procedure. It may further be beneficial that the guidewire storage location be protected from the environment to keep the guidewire clean and/or sterile and to prevent the length of guidewire from interfering with the access procedure. 
     Returning now to  FIGS. 5-7 , an embodiment of insertion device  110  according to the present inventions is depicted. As shown, the insertion device includes a main housing  120 , which has a top side  120 A and a bottom side  120 B when oriented during use by a clinician and for reference in these figures. As depicted, main housing  120  may include handles  121 , where, as referred to in the figures, the right handle  121 A and the left handle  121 B are depicted from the perspective of a clinician, when insertion device  110  is oriented as it would be during use by the clinician. Handles  121 A and  121 B are configured to ergonomically facilitate the user gripping insertion device  110  by holding main housing  120  using a single hand as well as to facilitate aspiration, as will be further described below. Each handle  121 A and  121 B comprise a full-ring finger grip ( 134 B,  134 C) closer to main housing  120  and an open-ring finger grip ( 134 A,  134 D) further from main housing  120 . However, it will be recognized that any combination of full-ring and open-ring finger grips may be utilized in the present invention, as well as varying numbers of finger grips on either side of main housing  120  can be employed when practicing the inventions described herein. In this embodiment, handles  121 A and  121 B are provided symmetrically on the right and left side of main housing  120  to permit use by both right-hand dominant and left-hand dominant clinicians, as well as to allow for a variety of finger orientations as may be preferred by various individual clinicians. For example, in one method of gripping insertion device  110 , a right-hand dominant user would hold insertion device  110  in the right hand with the top  120 A of main housing  120  pointing upwards, and the palm of the user&#39;s hand oriented against the bottom  120 B of main housing  120 . The orientation and position of fingers can vary according to the preference and comfort of the clinician. For instance, a user may choose to orient his or her grip so that the tip of the first, or index, finger is inserted in the full ring grip of the right handle  121 A. The second finger may be inserted in the full ring closest to main housing  110  of left handle  121 B. The third finger could then be positioned in the open ring of handle  121 B, further from main housing  110 . It should be noted that the reference to “top” and “bottom” and “right” and “left” is used only for purposes of describing the possible gripping and ergonomic disposition of insertion device  110 , and is not meant in any way to suggest that the “top” and “bottom” and “right” and “left” orientation is to be maintained during use of the insertion device  110 . For instance, a user may find the most comfortable and effective orientation of insertion device  110  is to hold insertion device  110  with what is referred to here as the right handle  121 A oriented up, allowing the clinician to have the fifth finger of the hand nearest to the patient, using the small finger to brace the hand against the patient and help stabilize insertion device  110  and allow for even greater control of needle  140  movement during insertion and aspiration. With insertion device  110  being grasped by the fingers of the dominant hand, for example as described above, the clinician&#39;s thumb is free to manipulate, for example, plunger  152  by use of grip  154 , guidewire  160 , and sheath movement tab  172 . Additional details of use of embodiments of this invention are described below. 
     Main housing  120  is composed of thermoplastic such as polycarbonate and is substantially transparent, although as with other embodiments of the present inventions, manufacture of main housing  120  may be performed using other suitable materials will readily be apparent to a person of skill in the art. If main housing  120  is made using a substantially non-transparent material, such as a substantially translucent or substantially opaque thermoplastic, it may be desirable to include cut-out or window areas in main housing  120  to permit a user to visualize needle hub  142  or vacuum chamber  150  during use. Main housing  120  is illustrated herein as comprising a single, unitary piece, manufactured using a suitable method such as injection molding or 3D printing. However, it will be appreciated that main housing  120  could be constructed using multiple pieces, such as a top and a bottom in a shell-like arrangement, as long as the bonding of such top and bottom pieces was sufficiently air-tight to allow an appropriate vacuum to be maintain in vacuum chamber  150  and lumens  135  and  136 . In the present embodiment, however, maintenance of the seal in vacuum chamber  150  would not be dependent on a seal between a top portion and a bottom portion of housing  120  because in this embodiment vacuum chamber  150  comprises a unitary syringe barrel. 
     A hollow piercing structure, such as needle  140 , is affixed to a needle hub  142  at the proximal end  140 A of needle  140 . The proximal end  140 A of the needle  140  fits into a pocket in needle hub  137  and is fixed in place using an appropriate adhesive or other appropriate means as would be appreciated by a person of skill in the art, including, for instance, but not limited to, ultra-violet cured epoxy. Needle  140  extends distally from needle hub  137  to distal end  140 B of the needle  140  where it terminates at a point or other sharp end suitable for piercing skin of a patient, such as bevel  141 . Needle hub  137  is configured to fit on the needle hub attachment  126  at the distal end of main housing  120 . Needle hub attachment  126  may or may not taper from the proximal end to the distal end, depending on the configuration of needle hub  137 . In this embodiment, like other embodiments that include a needle hub, needle hub attachment  126  is a male Luer-Lok connection fitting and needle hub  137  is a corresponding female Luer-Lok fitting. A person of skill in the art will appreciate that other appropriate fittings may be used, including friction fittings, to create a connection between needle hub  137  and needle hub attachment  126 . Appropriate fittings or other means of attaching the needle to the housing will create a connection that is substantially air-tight, as will be explained below, and will allow for a pressure differential to be maintained between the distal end  140 B of needle  140  and vacuum chamber  150  of at least about 300 mmHg. In some embodiments of the inventions, it may be desirable to provide an adjustable or removable connection between needle  140  and main housing  120  that permit the user to rotate the orientation of needle  140  to adjust the direction of angle of needle bevel  141  relate to main housing  120 . Such adjustment of needle bevel  141  may be useful to accommodate ambidextrous usage of insertion device  110  and to accommodate clinician personal preferences. It will also be appreciated that alternative embodiments of the inventions described herein need not require that needle  140  is removable. It will be appreciated that where needle  140  is not removable, needle  140  may be permanently attached to or otherwise integral with main housing  120 . Whether needle  140  is bonded to needle hub  137  or directly to main housing  120 , it is envisioned that a bond strength of at least about 3 in-lbs would be adequate for the practice of the inventions disclosed herein, recognizing that lower or higher needle bond strengths may be sufficient or even preferable depending on the specific application to which the embodiments of the inventions are used. 
     Vacuum chamber  150  is included in insertion device  110 , allowing for the creation of a suction sufficient to aspirate fluid from the distal end  140 B of needle  140 , through the lumen of needle  140 , and into vacuum chamber  150 . As previously explained, it is believed that a suction of at least approximately 300 mmHg should be sufficient for the practice of the inventions described herein, although it will be apparent that lower pressure differentials may be sufficient, depending on the specific design of the embodiment and the specific application in which it will be used. As depicted in  FIGS. 5-7 , vacuum chamber  150  is depicted as the barrel of a syringe. However, and as described previously, it will be apparent from this disclosure that vacuum chamber  150  need not be a separate syringe barrel. Alternatively, vacuum chamber  150  can be a portion of and contiguous with main housing  120 . The volume of vacuum chamber  150  preferably is sufficient to provide for the aspiration of a volume of at least 4 milliliters of fluid, although a smaller volume could also be acceptable to practice the inventions disclosed herein. Distal end  152 B of plunger  152  includes a head  153  that is capable of creating a substantially air-tight annular seal against the wall of vacuum chamber  150 . In this embodiment, vacuum chamber  150  is depicted with nozzle  151  that fits substantially securely, by use of a male Luer-Lok fitting, into a female Luer-Lok fitting that is included in main housing  120  as shown in  FIG. 7 . In this embodiment, the female Luer-Lok fitting is molded (for instance using injection molding) or printed (for instance using 3D printing) as an integral part of housing  120 . Alternative fittings, such as suitable friction fittings, would also be appropriate in this embodiment of insertion device  110 . The fitting of nozzle  151  to housing  120  makes a substantially air-tight seal between vacuum chamber  150  and lumen  135  in main housing  120 . Upon attachment of vacuum chamber  150  to main housing  120 , vacuum chamber  150  communicates with lumen  135 , which, in turn, communicates with the lumen of needle  140  from the distal opening  137  in housing  120  such that fluid can flow from distal end  140 B of needle  140 , through the needle lumen, through lumen  137 , through nozzle  151 , and into vacuum chamber  150 . In other words, lumen  137  serves as a conduit between the lumen of needle  140  and vacuum chamber  150 . Proximal end  152 A of plunger  150  includes a grip  154  such as a full or partial ring. In the present embodiment, grip  154  is depicted as a partial ring. Grip  154  can be used by a clinician in when drawing back plunger  152  with his or her thumb to create a vacuum in vacuum chamber  150 . 
     Insertion device  110  further comprises a guidewire  160 . In this embodiment, guidewire  160  is disposed within guidewire housing  162 , although it will be understood that guidewire housing  162  is not necessary to practice the inventions disclosed herein. In this embodiment, guidewire housing  162  is removably attached to main housing  120  at guidewire housing connector  168 . Guidewire housing  162  may be retained onto handle  121 A (if insertion device  110  is used in the right hand) or onto handle  121 B (if insertion device  110  is used in the left hand) by the addition of a clip or other suitable retention structure (not shown) to handles  121 . Guidewire housing  162  may be rigid or flexible, and of sufficient length to hold the length of guidewire  150  that is not otherwise disposed within housing  120  or needle  140 . Further, guidewire housing  162  can be either removably or permanently attached to main housing  120 , or could be an integral part of main housing  120 . Guidewire housing  162  may additionally include cap  163 . If present, cap  163  could serve a variety of purposes, including isolating guidewire  160  from the surrounding environment or to prevent guidewire  160  from being pushed out the proximal end of guidewire housing  162 . Main housing  120  is configured to allow the movement of guidewire  160  from the distal end of guidewire housing  162  at or about connector  168  along guidewire feed region  164  into lumen  136  of main housing  120 . Lumen  136  connects with lumen  135  in the main housing  120  at a point proximal to the connection of needle hub  137  to needle hub attachment  126 . Lumen  136  is configured to receive guidewire  150  at opening  127 . In this embodiment, lumen  136  is further configured to be fitted with a valve  128  between opening  127  and the point where lumen  136  joins with lumen  135 . Valve  128  is configured to allow the passage of guidewire  150  but to prevent the substantial flow of air that would substantially defeat a vacuum created by the proximal movement of plunger  152  in vacuum chamber  150 . It will be recognized by a person of skill in the art that while in this embodiment valve  128  is located at opening  127 , valve  128  could be placed at any location along lumen  136 . Moreover, it will be recognized by a person of skill in the art that a valve may not be necessary if guidewire  150  fits within lumen  36  tightly enough to prevent the substantial flow of air through lumen  136  such that the creation of a vacuum in vacuum chamber  150  is defeated. For purposes of the inventions described herein, the seal between guidewire  160  and the wall of lumen  136 , whether or not value  128  is employed, should be able to maintain a pressure differential of at least about 300 mmHg, although the inventions described herein could be practiced if a pressure differential of less than 300 mmHg was maintained across lumen  136 . It is contemplated that most commonly insertion device  110  would be configured to accommodate a 0.038-inch sized guidewire, although various other sized guidewires could be suitable depending on the specific applications insertion device  110  was intended. 
     In this embodiment, guidewire feed region  164  includes wheel  165  between guidewire housing connector  168  and opening  127  to lumen  136 , over which guidewire  150  passes. Wheel  165  is disposed about an axle  166  that, in turn, is held onto housing  120  suing two opposed axle mounts  167 A and  167 B, on the right and left sides, respectively, of housing  120 . Wheel  165  is configured to turn about axle  166 . Alternatively, wheel  165  may be fixed to axle  166 , and axle  166  is configured to turn within axle mounts  167 A and  167 B. Guidewire feed region  164  is generally configured to be accessible by the thumb of the user while gripping main housing  120  with one hand; however, the configuration may be altered in some embodiments of the present inventions such that the guidewire feed region  164  is accessible by a finger of the one hand of the user gripping main housing  120 . In this embodiment, the thumb of the user can be used to advance guidewire  150  through needle  140  toward distal end  140 B of needle  140  and into the targeted body space of the patient. Of course, the thumb of the user may also be used to move guidewire  150  in the opposite direction, toward proximal end  140 A of needle  140 , for instance if guidewire  150  needs to be retracted into the lumen of needle  140  and repositioned, or otherwise retracted from the targeted body space. Wheel  165  can serve to provide tactile feedback to the clinician while advancing (or retracting) guidewire  150 , as well as to provide a raised surface against while to press guidewire  150  to assist in gripping of guidewire  160  to more efficient movement of guidewire  150 . 
     In this embodiment, insertion device  110  includes a sheath  171  that is coaxially moveably disposed about needle  140 . Sheath  171  is attached to sheath movement element  170  at sheath hub  174 . Notably, sheath  171  may be permanently or removably attached to sheath hub  174 . Where sheath  171  is removably attached to sheath hub  174 , sheath may be detached after the placement of the guidewire in the targeted tissue so that a port can be maintained into the targeted tissue space. In this embodiment, sheath movement element  170  includes sheath movement tab  172 , arms  173 A and to  173 B, sheath hub  174 , tab  175 , and grooves  176 A and  176 B. Sheath movement tab  172  is configured to permit a user, while gripping main housing  120  with a single hand, to move sheath movement element  170  in proximal and distal directions using the thumb of the single hand. Movement of sheath movement element  170  in a distal direction would result in sheath  171  moving coaxially along needle  140  toward distal end  140 B of needle  140 . Further, both the length of sheath  171  and the degree of movement permitted of sheath movement element  170  is sufficient to permit the furthest movement of sheath  171  in a distal direction to cover distal end  140 B of needle  140  to shield distal end  140 B of needle  140 . Conversely, movement of sheath movement element  170  in a distal direction would result in sheath  171  moving coaxially along needle  140  away from distal end  140 B of needle  140 . Continued movement of sheath movement element  170  would result in the exposure of needle distal end  140 B. Movement of the sheath movement element  170  in a distal direction from the position depicted in  FIG. 5  results in tab  175  of sheath movement element  170  passing over ridge  124  and resting in notch  125  of housing  120 . Notch  125  is created on the proximal end by ridge  124  and on the distal end by stopper  125 . The contact of tab  175  with stopper  125  arrests the distal advancement of sheath movement element  170 , and therefore the extent of movement of sheath  160  in the distal direction. In use, the passage of tab  175  over ridge  124  creates tactile feedback to inform the clinician that the furthest extent of sheath  160  advancement is being reached. In addition, when tab  175  is resting in notch  123 , proximal movement of sheath movement element  170  is partially restricted by ridge  124 , thereby reducing the possibility of accidental retraction of sheath  171 . Sheath movement element  170  is moveably attached to housing  120  by the joining of grooves  176 A and  176 B of sheath movement element  170  to rails  139 A and  139 B of housing  120 . 
     In this embodiment of insertion device  110 , sheath movement element  170  is disposed on the top  120 A of housing  120  and guidewire  150  is also disposed on the top  120 A of housing  120 . However, it will be appreciated by persons of skill in the art that the inventions described herein can be practiced with both the sheath movement element  170  and the guidewire  150  disposed on the opposite sides of housing  120 , as described elsewhere herein. 
     As indicated above, the embodiment of the inventions disclosed herein, where the insertion device includes a sheath and finger grips such as depicted in  FIGS. 5-7  can be used to perform a venous access procedure according to the inventions disclosed herein using the ultrasound-guided modified Seldinger Technique.  FIG. 8  shows an example view of this embodiment in use. In use, a clinician grips the insertion device  110  in the dominant hand and an ultrasound probe (not shown) in the non-dominant hand. In a right-hand dominant user, the index finger is inserted into the closed-ring finger grip  134 B on the right side (as oriented in  FIGS. 5-7  from the perspective of viewing insertion device  110  from the proximal end) of main housing  120 . The clinician&#39;s middle finger of the dominant hand is inserted into the closed-ring finger grip  134 C on the left side of main housing  120 , and the ring finger of the dominant hand is situated in the open-ring finger grip  134 D on the left side of main housing  120 . When prepared for use, guidewire  160  may be positioned within conduit  136  or in the lumen of needle  140 , with the distal end of guidewire  160  reasonably close to, but proximal to, tip  141  of needle  140 . Such pre-positioning of guidewire  160  in conduit  136  or in the lumen of needle  140  can assist in the rapid deployment of guidewire  160  into the targeted body space. However, such pre-positioning of guidewire  160  or other wire-like structure to be inserted into the targeted body space within the lumen of needle  140  is not necessary for the practice of this method. 
     With sheath movement element  170  in a distal position, such that the tip  141  of needle  140  is exposed, the clinician presses the tip  141  of needle  140  against a patient&#39;s skin and uses it to penetrate through tissue. While the clinician is inserting the needle, the clinician uses the ultrasound probe and the cross-sectional and longitudinal images produced by the ultrasound machine to follow the progress of needle  140  as it pierces through the tissue. Also while the clinician is inserting needle  140  through patient tissue, the clinician uses the thumb of the dominant hand to draw back plunger  152  using grip  154 , thereby creating a suction in vacuum chamber  150 . The suction created in vacuum chamber  150  in turn results in a suction at tip  141  of needle  140  through conduit  135 . Body fluid is drawn from the region around tip  141  of needle  140 , through the needle lumen, through conduit  135  and into vacuum chamber  150 . When the tip  141  of needle  140  accesses and pierces the targeted vein, blood flows through the lumen of needle  140 , into conduit  135  and into vacuum chamber  150 . Visualization of blood in needle hub  142 , conduit  135 , and/or vacuum chamber  150  indicates to the clinician that the targeted vein has been reached and punctured. It will be appreciated that where this process is applied for the access of targeted body regions other than veins, the appearance of other, appropriate body fluids in needle hub  142 , conduit  135 , and/or vacuum chamber  150  would indicate that the particular targeted body region had been reached. 
     Once the targeted body region, in this example the vein, has been reached, the clinician stops moving needle  140  forward. The clinician then uses the thumb of the dominant hand to push sheath movement tab  172  to move sheath movement element  170  in a distal direction. The distal movement of sheath movement element  170  results in the distal coaxial movement of sheath  171  in a distal direction to cover tip  142  of needle  140 . This deployment of sheath  170  in a distal direction to cover tip  142  of needle  140  partially secures access in the vein and tends to prevent further tissue damage by shielding the patient&#39;s tissue from the sharp tip  142  of needle  140 . When sheath  170  has been advanced to cover tip  142  of needle  140 , the clinician uses the thumb of the dominant hand to press guidewire  160  against roller  165  and advance guidewire  160  in a distal direction by repeatedly moving the thumb along the guidewire feed region  164  and over roller  165 . As explained above, roller  165  may be easily replaced in some embodiments of the inventions disclosed herein with a protrusion, button, or other structure in guidewire feed region  164  configured to aid the clinician in advancing guidewire  160  in a distal direction and/or retracting guidewire  160  in a proximal direction. 
     In this manner, the clinician uses the thumb to advance guidewire  160  in a distal direction, through conduit  136  and valve  127  into the lumen of needle  140 , past the tip  141  of needle  140  and ultimately past the distal end of sheath  171  into the vein or other targeted body space. Because the access device allows for single-handed venipuncture and insertion, the operator can use ultrasound imaging to visualize the needle tip while it is inside of the vein and the guidewire as it is advanced into the vein. Consequently, the risk of tissue injury diminishes. Furthermore, retaining ultrasound visibility allows the operator to ensure that the guidewire is going into the targeted vein as he inserts it. After the operator inserts the guidewire into the vein to the desired length, the access device is removed while the guidewire remains in place for dilation and catheter, sheath, or cannula insertion. 
       FIGS. 9-12  depict an embodiment of the inventions disclosed herein. Insertion device  210  comprises a main housing  220  that includes, for reference in these figures, a top side  220 A and bottom side  220 B. Main housing  220  may include handles  221 A and  221 B, on the right and left sides of main housing  220 , respectively. Handles  221 A and  221 B are configured to facilitate the ergonomic gripping of insertion device  210  by a user, or clinician, with a single hand. As shown in the figures, in this embodiment, handles  221 A and  221 B each comprise two grips, where the grip closer to main housing  220  is a full-loop finger grip and the grip away from main housing  220  is a partial-loop finger grip. As is apparent to a person of skill in the art, handles  220 A and  220 B would be configured to include unequal number of grips on each side of main housing  220 , and such grips may be any appropriate combination of full-loop or partial-loop grips, as well as other, non-loop type grips. Main housing  220  is comprised of thermoplastic such as polycarbonate and is transparent, although manufacture using other suitable materials will be readily apparent to a person of skill in the art. If main housing  220  is constructed of a translucent or opaque material, main housing  220  may be configured to include transparent regions (not shown) to permit the user to view the inside of vacuum chamber  250  and/or conduit  235 , as will be further described below. 
     Main housing  220  includes a main housing cap  229 , additional details of which are depicted in  FIG. 10 . Main housing cap  229  includes needle attachment opening  231 , conduit  236 A, and channel  235 A. Main housing cap  229  is formed of substantially transparent thermoplastic such as polycarbonate. However, it will be recognized that main housing cap  229  may be formed of other materials as well, and may be translucent, substantially opaque, or opaque. In the event that main housing cap  229  is not formed of material that is substantially transparent, it may be desirable to form main housing cap  229  with a clear, or substantially transparent, section, such as a window, that would permit a user to visualize contents of channel  235 A while insertion device  210  is in use, in particular to allow user to visualize the presence of fluid from the targeted body space in channel  235 A while aspirating into vacuum chamber  250 . In this embodiment, needle attachment opening  231  is continuous with conduit  236 A, which runs through main housing cap  229 . When main housing cap  229  is mounted onto main housing  220 , conduit  236 A in main housing cap  229  is contiguous with conduit  236 B in main housing  220 . Main housing cap  229  can be affixed to main housing  220  using a variety of suitable methods such as, for instance, ultrasonic welds, epoxy, or resin for a permanent attachment. It will be appreciated that main housing cap  229  may also be temporarily affixed to main housing  220  using clips, screws, or other suitable means. In an instance where main housing cap  229  if temporarily affixed to main housing  220 , it will be recognized by a person of skill in the art that additional seals may be deployed to ensure that conduits  235 A,  235 B,  236 A, and  236 B are substantially air-tight during use such that the necessary pressure differential, as described herein, can be maintained to permit the aspiration of body fluids from the targeted body space. 
     A hollow piercing structure, such as needle  240 , is included in insertion device  210 . Proximal end  240 A of needle  240  is affixed, through needle attachment opening  231  and through conduit  236 A of main housing cap  229 , into conduit  236 B of main housing  220 . Various methods of affixing needle  240  to main housing cap  229  and main housing  220  will be appreciated, including plastic cement, appropriate epoxy, and ultraviolet curing. However, to practice the inventions disclosed herein, it is not necessary that needle  240  be permanently affixed to main housing cap  229  and/or main housing  220 . Indeed, it will be appreciated that in some embodiments of the inventions disclosed herein, it may be desirable for needle  240  be to movably and/or removably attached to main housing cap  229  and/or main housing  220  so that, for example, needle  240  can be changed or for example, the orientation of needle  240  can be altered so that the direction of bevel  241  of needle  240  can be adjusted relative to the orientation of housing  220 . 
     The region around proximal end  240 A of needle  240  includes an opening  243  along the shaft of needle  240  that is in communication with the lumen of needle  240 . Opening  243  on needle  240  is oriented to communicate with conduit  235 A to permit the flow of aspirated body fluids from the region of the distal end  240 B of needle  240 , through the lumen of needle  240 , and into conduit  235 A. Such aspirated body fluids would be permitted to flow through conduit  235 A into conduit  235 B and ultimately into vacuum chamber  250 . 
     Insertion device  210  further includes a vacuum chamber  250  configured to receive plunger  252 . Vacuum chamber  250  is in communication with conduits  235 B and  235 A such that pressure differential created in vacuum chamber  250  will create a suction passing through conduit  235  into the lumen of needle  240 , to permit the aspiration of fluids through the distal tip  240 B of needle  240 . Plunger  252  includes a proximal end  252 A and a distal end  252 B. Distal end  252 B of plunger  252  includes a head  253  that has a size and shape sufficient to create a substantially air-tight annular seal between the edge of head  253  and the side walls of vacuum chamber  250 . Proximal end  252 A of plunger  252  includes a handle  254  that is configured to receive the thumb or finger of a user while using insertion device  210 . Handle  254  in this embodiment is depicted as an open ring; however, it will be appreciated that handle  254  can be configured as a closed ring, a tab, or any other suitable design that will permit the user to draw back plunger  252  in vacuum chamber  250  with a digit of the single hand used to hold insertion device  210  while in use. It will also be appreciated that while vacuum chamber  250  is depicted in this embodiment as a contiguous part of main housing  220 , vacuum chamber  250  could be a separate structure, such as a syringe, that may be coupled to main housing  220  in a substantially air-tight manner to permit the creation of a pressure differential sufficient to aspirate fluids from the targeted body cavity of a patient. 
     Insertion device  210  is further configured to include guidewire  260 . In this embodiment, the proximal region of guidewire  260  is disposed within guidewire housing  262 , which, in turn, is removably attached to main housing  250  at guidewire housing connector  268 . Guidewire housing  262  may be either rigid or flexible, and may be permanently or removably attached to main housing  220 . Further, as shown in the Figures, guidewire housing  262  may be configured to receive cap  263 . Cap  263  can serve to retain guidewire  260  in guidewire housing  262 , as well as to isolate guidewire  260  from potential contaminants in the surrounding environment. 
     Guidewire  260  spans guidewire feed region  264 . Main housing  220  is configured to receive the distal end of guidewire  260  in conduit  236 . In this embodiment, valve  228  is provided and configured to permit guidewire  260  to pass through it prior to entering conduit  236 . As shown, valve  228  is held in place on main housing  220  by use of cap  230 . Cap  230  is affixed to main housing  220  as a snap-fit assembly. Like valve  228 , cap  230  is configured to permit guidewire  260  to pass through it prior to entering conduit  236  as shown, for example, in  FIG. 12 . It will be appreciated that cap  230  may be affixed to main housing  220  as a snap-fit assembly or in a variety of other means, such as epoxy, plastic cement, or ultra-violet curing. Additionally, while the figures depicting this embodiment show valve  228  at a proximal edge of main housing  228 , it will be understood that valve  228  may be placed not only at the entrance of conduit  236 , but alternatively at any location along conduit  236 . For example, valve  228  could be placed between a distal end of main housing  220  and a proximal end of main housing cap  229 . In this latter configuration, cap  230  would not be necessary to hold valve  228  in place. 
     Valve  228  serves in insertion device  210  to prevent the substantial movement of air through conduit  236 B such that the pressure differential created by the proximal movement of plunger  252  in vacuum chamber  250  would be defeated. Preferably, valve  228  would provide an air-tight seal around the guidewire of at least about 300 mmHg of pressure. Valve  228  may be pressure-sensitive. However, it will be appreciated that the function of the inventions disclosed herein, and specifically the aspiration of fluid from a targeted body space through the lumen of needle  240  and ultimately into vacuum chamber  250 , the inventions disclosed herein could be practiced with a vacuum of more or less than about 300 mmHg pressure, depending on the specific application and design of the insertion tool  210 . It will also be apparent that valve  228  may not be necessary to maintain the necessary vacuum, if the entry to conduit  236 B is sized so that the guidewire itself creates a sufficient seal to substantially prevent the flow of air through conduit  236 B during aspiration. It will be apparent to persons of skill in that art that other suitable means to maintain pressure differential across conduit  236  may be employed. For instance, conduit  236  may be configured with two valves, in which case guidewire  260  (or other wire-like structure to be inserted into the targeted body space) can be preloaded into conduit  236  with the distal end of guidewire  260  positioned between the two valves. 
     When insertion tool  210  is prepared for use, it may be beneficial that guidewire  260  is configured within needle  240 , with the distal end of guidewire  260  close to distal end  240 B of needle  240 . The tip of the distal end of guidewire  260 , however, should not extend through the distal end  240 B of needle  240 , and should remain clear of bevel  241  of needle  240 . However, when the distal tip of guidewire  260  is placed near the distal end  240 B of needle  240  when insertion device  210  is prepared for use, the user is able to more rapidly advance guidewire  260  into the targeted body space, thus securing access to the targeted body space, as soon as puncture of the targeted body space is confirmed, such as through the aspiration of appropriate body fluids through conduit  235  and/or into vacuum chamber  250 . 
     The use of the inventions disclosed herein is not limited to devices that include a sheath. For instance, the embodiment depicted in  FIGS. 9-12  can be used to perform a venous access procedure using the ultrasound-guided modified Seldinger Technique according to the invention described herein.  FIG. 13  shows an example view of this embodiment in use. In use, a clinician grips the insertion device  210  in the dominant hand and an ultrasound probe (not shown) in the non-dominant hand. In a right-hand dominant user, the index finger is inserted into the closed-ring finger grip  234 B on the right side (as oriented in  FIGS. 9-12  from the perspective of viewing insertion device  210  from the proximal end) of main housing  220 . The clinician&#39;s middle finger of the dominant hand is inserted into the closed-ring finger grip  234 C on the left side of main housing  220 , and the ring finger of the dominant hand is situated in the open-ring finger grip  234 D on the left side of main housing  220 . When prepared for use, guidewire  260  may be positioned within conduit  236 , with the distal end of guidewire  260  reasonably close to, but proximal to, tip  241  of needle  240 . Such pre-positioning of guidewire  260  in the lumen of needle  240  can assist in the rapid deployment of guidewire  260  into the targeted body space. However, such pre-positioning of guidewire  260  within the lumen of needle  240  is not necessary for the practice of this method. 
     The clinician presses the tip  241  of needle  240  against a patient&#39;s skin and uses it to penetrate through tissue. While the clinician is inserting the needle, the clinician uses the ultrasound probe and the image produced by the ultrasound machine to follow the progress of needle  240  as it pierces through the tissue. Also while the clinician is inserting needle  240  through patient tissue, the clinician uses the thumb of the dominant hand to draw back plunger  252  using grip  254 , thereby creating a suction in vacuum chamber  250 . The suction created in vacuum chamber  250  in turn results in a suction at tip  241  of needle  240  through conduit  235 . Body fluid is drawn from the region around tip  241  of needle  240 , through the needle lumen, through conduit  235  and into vacuum chamber  250 . When the tip  241  of needle  240  accesses and pierces the targeted vein, blood flows through the lumen of needle  240 , into conduit  235 A and  235 B and into vacuum chamber  250 . Visualization of blood in conduit  235 A, conduct  235 B, and/or vacuum chamber  250  indicates to the clinician that the targeted vein has been reached and punctured. It will be appreciated that where this process is applied for the access of targeted body regions other than veins, the appearance of other, appropriate body fluids in conduit  235 A conduit  235 B, and/or vacuum chamber  250  would indicate that the particular targeted body region had been reached. 
     Once the targeted body region, in this example the vein, has been reached, the clinician stops moving needle  240  forward. The clinician uses the thumb of the dominant hand to press guidewire  260  against protrusion  265  and advance guidewire  260  in a distal direction by repeatedly moving the thumb along the guidewire feed region  264  and over protrusion  265 . As explained above, protrusion  265  may be easily replaced in some embodiments of the inventions disclosed herein with a wheel, button, or other structure in guidewire feed region  264  configured to aid the clinician in advancing guidewire  260  in a distal direction and/or retracting guidewire  260  in a proximal direction. 
     In this manner, the clinician uses the thumb to advance guidewire  260  in a distal direction, through conduit  236  and valve  228  into the lumen of needle  240 , past the tip  241  of needle  240  and into the vein or other targeted body space. Because the access device allows for single-handed venipuncture and insertion, the operator can use ultrasound imaging to visualize the needle tip while it is inside of the vein and the guidewire as it is advanced into the vein. Consequently, the risk of tissue injury diminishes. Furthermore, retaining ultrasound visibility allows the operator to ensure that the guidewire is going into the targeted vein as he inserts it. After the operator inserts the guidewire into the vein to the desired length, the access device is removed while the guidewire remains in place for dilation and catheter, sheath, or cannula insertion. 
       FIGS. 14-16  depict an embodiment of the invention, insertion device  310 . As has been explained, one of the benefits of the inventions disclosed herein is to permit a clinician, or user, to insert an object, such as a guidewire, into a targeted body space to secure access to the targeted body space using one hand. With the inventions disclosed here, the clinician can puncture the body of the patient with a hollow piercing object, such as a needle, confirm access to the targeted body space by aspirating body fluid through the hollow piercing structure, and advance a guidewire to secure access into the targeted body space, all using a single hand. Typically, the dominant hand of the clinician will be used to secure access to the targeted body space, while the clinician&#39;s other hand is used to hold an ultrasound probe or other visualization tool to watch the advancement of the hollow piercing structure into the patient, watch the movement of the hollow piercing structure within the patient, and watch the advancement of the guidewire into the patient. As the insertion devices that embody the inventions described herein are configured to be operated by one hand, ergonomic considerations should be evaluated when designing insertion tools according to the inventions described herein. Considering the present embodiment of the inventions, insertion device  310  is configured to be held by clinician using a single hand with a generally overhand grip. Comparing the present embodiment to other possible embodiments of the inventions described herein, it will be clear to a person of skill that the described inventions can be practiced using a variety of configurations and ergonomically beneficial designs. Such designs can be configured to be used in the right hand, in the left hand, or in either the right hand or the left hand. It will be clear that there are certain economic and practical benefits that can be obtained by employing the disclosed inventions in ambidextrous configurations, i.e., configurations that be used in either the right hand or the left hand. 
     The embodiment depicted in  FIGS. 14-16 , like other embodiments disclosed herein, is configured to be used in either the right hand or the left hand of a clinician. As shown, insertion device  310  includes main housing  320 . Main housing  320 , for reference in the figures, has a top side  320 A and a bottom side  320 B. Main housing  320  includes handle  321  toward the distal end of main housing  320 , extending from bottom side  320 B and main housing  320 . Handle  321  is used to facilitate the gripping of insertion device  310  using a single hand. Typically, insertion device  310  is gripped using only the dominant hand of a clinician, or user, as will be described in more detail below. Handle  321  can be configured using a variety of arrangements. In this embodiment, handle  321  is preferably configured to allow the clinician to grip the distal end of handle  321  with either the middle finger or the index finger of the dominant hand. In the present embodiment, main housing  320  is composed of thermoplastic such as polycarbonate and is substantially transparent. Construction of main housing  320  using material that is substantially transparent facilitates the visualization by the clinician of body fluids that are aspirated into various portions of main housing  320 , as will be explained in further detail below. If main housing  320  is made of a substantially non-transparent material, such as a substantially translucent or substantially opaque thermoplastic, it may be desirable to include cut-out or other window-type areas in housing  320  to permit the clinician to visualize into various conduits (such as conduit  335 ) and/or vacuum chamber  350  during use as will be explained in further detail below. The proximal end of main housing  320 , in this embodiment, has a rounded end that may increase grip stability and comfort in the hand of the user. In addition, the bottom  320 B of main housing  320  is configured to have a comfort grip shape that can add to stability and comfort in the hand of the user. 
     Main housing  320  includes a main housing cap  329 . Main housing cap  329  includes needle attachment opening  331 , conduit  336 A, and channel  335 A. Main housing cap  329  is formed of substantially transparent thermoplastic such as polycarbonate. However, it will be recognized that main housing cap  329  may be formed of other materials as well, and may be translucent, substantially opaque, or opaque. In the event that main housing cap  329  is not formed of material that is substantially transparent, it may be desirable to form main housing cap  329  with a clear, or substantially transparent, section, such as a window, that would permit a user to visualize contents of channel  335 A while insertion device  310  is in use, in particular to allow user to visualize the presence of fluid from the targeted body space in channel  335 A while aspirating into vacuum chamber  350 . In this embodiment, needle attachment opening  331  is continuous with conduit  336 A, which runs through main housing cap  329 . When main housing cap  329  is mounted onto main housing  320 , conduit  336 A in main housing cap  329  is contiguous with conduit  336 B in main housing  320 . Main housing cap  329  can be affixed to main housing  320  using a variety of suitable methods such as, for instance, ultrasonic welds, epoxy, or resin for a permanent attachment. It will be appreciated that main housing cap  329  may also be temporarily affixed to main housing  320  using clips, screws, or other suitable means. In an instance where main housing cap  329  is temporarily affixed to main housing  320 , it will be recognized by a person of skill in the art that additional seals may be deployed to ensure that conduits  335 A,  335 B,  336 A, and  336 B are substantially air-tight during use such that the necessary pressure differential, as described herein, can be maintained to permit the aspiration of body fluids from the targeted body space. 
     A hollow piercing structure, such as needle  340 , is included in insertion device  310 . Proximal end  340 A of needle  340  is affixed, through needle attachment opening  331  into conduit  336 A of main housing cap  329 . Various methods of affixing needle  340  to main housing cap  329  and main housing  320  will be appreciated, including plastic cement, appropriate epoxy, and ultraviolet cured cement. However, to practice the inventions disclosed herein, it is not necessary that needle  340  be permanently affixed to main housing cap  329  and/or main housing  320 . Indeed, it will be appreciated that in some embodiments of the inventions disclosed herein, it may be desirable for needle  340  be to movably and/or removably attached to main housing cap  329  and/or main housing  320  so that, for example, needle  340  can be changed or for example, the orientation of needle  340  can be altered so that the direction of bevel  341  of needle  340  can be adjusted relative to the orientation of housing  320 . Changes to the orientation of bevel  341  of needle  340  can be particularly useful when adapting insertion device  310  for ambidextrous use or for the personal preference of bevel  341  orientation of a clinician. 
       FIG. 16  depicts the proximal end  340 A of needle  340  terminating within conduit  336 A. It should be noted, however, that proximal end  340 A of needle  340  could be extended into conduit  336 B. With such a design, needle  340  should be configured so that the region around proximal end  340 A of needle  340  includes an opening (not shown) along the shaft of needle  340  that is in communication with the lumen of needle  340 . This opening on needle  340  is oriented to communicate with conduit  335 A to permit the flow of aspirated body fluids from the region of the distal end  340 B of needle  340 , through the lumen of needle  340 , and into conduit  335 A. Such aspirated body fluids would be permitted to flow through conduit  335 A into conduit  335 B and ultimately into vacuum chamber  350 . 
     Insertion device  310  further includes vacuum chamber  350  configured to receive plunger  352 . Vacuum chamber  350  is in communication with conduits  335 B and  335 A such that pressure differential created in vacuum chamber  350  will create a suction passing through conduit  335  into the lumen of needle  340 , to permit the aspiration of fluids through the distal tip  340 B of needle  340 . Plunger  352  includes a proximal end  352 A and a distal end  352 B. Distal end  352 B of plunger  352  includes a head  353  that has a size, shape, and composition sufficient to create a substantially air-tight annular seal between the edge of head  353  and the side walls of vacuum chamber  350 . Distal end  352 B of plunger  352  also includes handles  354 A and  354 B that are configured to receive a finger of the user while using insertion device  310 . Handles  354 A and  354 B are contiguous with rails  355 A and  355 B, respectively. As depicted in  FIG. 15 , rails  355 A and  355 B are part of a continuous structure in this embodiment that wraps around the proximal end  352 A and plunger  352 . Rails  355 A and  355 B fit into channels  333 A and  333 B, respectively, in vacuum chamber  350 . It will be noted that the attachment of handles  354 A and  354 B to the distal end  352 B and plunger  352  is made so that handles  354 A and  354 B do not interfere with the seal between head  353  of plunger  352  and the interior surface of vacuum chamber  350 . Channels  333 A and  333 B are blocked at the proximal end of vacuum chamber  350  by the addition of ring  380 . Also as shown in  FIGS. 14 and 15 , the distal-facing ends of handles  354 A and  354 B are configured with finger dimples in which the finger of the user can rest to increase grip stability and comfort. 
     Insertion device  310  is further configured to include guidewire  360 . In this embodiment, the proximal region of guidewire  360  is disposed within guidewire housing  362 , which, in turn, is removably attached to main housing  320  at guidewire housing connector  368 . Guidewire housing  362  may be either rigid or flexible, and may be permanently or removably attached to main housing  320 . Further, as shown in the Figures, guidewire housing  362  may be configured to receive cap  363 . Cap  363  can serve to retain guidewire  360  in guidewire housing  362 , as well as to isolate guidewire  360  from potential contaminants in the surrounding environment. 
     Guidewire  360  spans guidewire feed region  364 . Main housing  320  is configured to receive the distal end of guidewire  360  in conduit  336 . In this embodiment, valve  328  is provided and configured to permit guidewire  360  to pass through it prior to entering conduit  336 . As shown, valve  328  seated in valve seat  344  and held in place at least by main housing cap  329 . Valve  328  is configured to allow guidewire  360  to pass through it prior to entering conduit  336 B. 
     Valve  328  serves in insertion device  310  to prevent the substantial movement of air through conduit  336 B such that the pressure differential created by the proximal movement of plunger  352  in vacuum chamber  350  would be defeated. Preferably, valve  328  would provide an air-tight seal around the guidewire of at least about 300 mmHg of pressure. However, it will be appreciated that the function of the inventions disclosed herein, and specifically the aspiration of fluid from a targeted body space through the lumen of needle  340  and ultimately into vacuum chamber  350 , the inventions disclosed herein could be practiced with a vacuum of more or less than about 300 mmHg pressure, depending on the specific application and design of the insertion tool  310 . It will also be apparent that valve  328  may not be necessary to maintain the necessary vacuum, if the entry to conduit  336 B is sized so that the guidewire itself creates a sufficient seal to substantially prevent the flow of air through conduit  336 B during aspiration. 
     When insertion tool  310  is prepared for use, it may be beneficial to use, depending on the specific application, that guidewire  360  is disposed within needle  340 , with the distal end of guidewire  360  close to distal end  340 B of needle  340 . The tip of the distal end of guidewire  360 , however, should not extend through the distal end  340 B of needle  340 , and should remain clear of bevel  341  of needle  340 . However, when the distal tip of guidewire  360  is placed near the distal end  340 B of needle  340  when insertion device  310  is prepared for use, the user is able to more rapidly advance guidewire  360  into the targeted body space, thus securing access to the targeted body space, as soon as puncture of the targeted body space is confirmed, such as through the aspiration of appropriate body fluids through conduit  335  and/or into vacuum chamber  350 . 
     As indicated above, the embodiment of the inventions disclosed herein, such as the insertion device  310  as depicted in  FIGS. 14-16 , can be used to perform a venous access procedure using the ultrasound-guided modified Seldinger Technique, employing the inventions disclosed herein.  FIG. 17  shows an example view of this embodiment in use. When prepared for use, guidewire  360  may be positioned within conduit  336 , with the distal end of guidewire  360  reasonably close to, but proximal to, tip  341  of needle  340 . Such pre-positioning of guidewire  360  in the lumen of needle  340  can assist in the rapid deployment of guidewire  360  into the targeted body space. However, such pre-positioning of guidewire  360  within the lumen of needle  340  is not necessary for the practice of this method. 
     A clinician grasps insertion device  310  in the dominant hand and an ultrasound probe (not shown) in the non-dominant hand. In particular, the clinician grasps housing  320  of insertion device  310  in the palm of the dominant hand with the middle finger of that hand around handle  321  and optionally the tip of the middle finger positioned in dimple  321 C. The index finger of the dominant hand is positioned on, for a right-hand dominant user, grip  354 A. The thumb of the dominant hand can be positioned near guidewire feed region  364 . The clinician presses the tip  341  of needle  340  against a patient&#39;s skin and uses it to penetrate through tissue. While the clinician is inserting the needle, the clinician uses the ultrasound probe and the image produced by the ultrasound machine to follow the progress of needle  340  as it pierces through the tissue. Also, while the clinician is inserting needle  340  through patient tissue, the clinician uses the index finger of the dominant hand to draw back plunger  352  using grip  354 A, thereby creating a suction in vacuum chamber  250 . 
     Alternatively, and as shown in  FIG. 18 , a clinician may grasp insertion device  310  in the palm of the dominant hand with the index finger of that hand around handle  321  and optionally the tip of the index finger positioned in dimple  321 C. The thumb of the dominant hand is positioned on, for a right-hand dominant user, grip  354 A. The clinician presses the tip  341  of needle  340  against a patient&#39;s skin and uses it to penetrate through tissue. While the clinician is inserting the needle, the clinician uses the ultrasound probe and the image produced by the ultrasound machine to follow the progress of needle  340  as it pierces through the tissue. Also, while the clinician is inserting needle  340  through patient tissue, the clinician uses the thumb of the dominant hand to draw back plunger  352  using grip  354 A, thereby creating a suction in vacuum chamber  350 . 
     The suction created in vacuum chamber  350  in turn results in a suction at tip  341  of needle  340  through conduit  335 . Body fluid is drawn from the region around tip  341  of needle  340 , through the needle lumen, through conduit  335  and into vacuum chamber  350 . When the tip  341  of needle  340  accesses and pierces the targeted vein, blood flows through the lumen of needle  340 , into conduit  335 A and  335 B and into vacuum chamber  350 . Visualization of blood in conduit  335 A, conduct  335 B, and/or vacuum chamber  350  indicates to the clinician that the targeted vein has been reached and punctured. It will be appreciated that where this process is applied for the access of targeted body regions other than veins, the appearance of other, appropriate body fluids in conduit  335 A conduit  335 B, and/or vacuum chamber  350  would indicate that the particular targeted body region had been reached. 
     Once the targeted body region, in this example the vein, has been reached, the clinician stops moving needle  340  forward. The clinician uses the thumb of the dominant hand to press guidewire  360  against protrusion  365  and advance guidewire  360  in a distal direction by repeatedly moving the thumb along the guidewire feed region  364  and over protrusion  365 . As explained above, protrusion  365  may be easily replaced in some embodiments of the inventions disclosed herein with a wheel, button, or other structure in guidewire feed region  364  configured to aid the clinician in advancing guidewire  360  in a distal direction and/or retracting guidewire  360  in a proximal direction. 
     In this manner, the clinician uses the thumb to advance guidewire  360  in a distal direction, through conduit  336  and valve  328  into the lumen of needle  340 , past the tip  341  of needle  340  and into the vein or other targeted body space. Because the access device allows for single-handed venipuncture and insertion, the operator can use ultrasound imaging to visualize the needle tip while it is inside of the vein and the guidewire as it is advanced into the vein. Consequently, the risk of tissue injury diminishes. Furthermore, retaining ultrasound visibility allows the operator to ensure that the guidewire is going into the targeted vein as he inserts it. After the operator inserts the guidewire into the vein to the desired length, the access device is removed while the guidewire remains in place for dilation and catheter, sheath, or cannula insertion. 
     The embodiment depicted in  FIGS. 19-21 , like other embodiments disclosed herein, is configured to be used in either the right hand or the left hand of a clinician. As shown, insertion device  410  includes main housing  420 . Main housing  420 , for reference in the figures, has a top side  420 A and a bottom side  420 B. Main housing  420  includes handles  421 A and  421 B toward the proximal end of main housing  420 , extending from bottom side  420 B and main housing  420 . Handles  421 A and  421 B are used to facilitate the gripping of insertion device  410  using a single hand. Typically, insertion device  410  is gripped using only the dominant hand of a clinician, or user, as will be described in more detail below. Handles  421 A and  421 B can be configured using a variety of arrangements. In this embodiment, handles  421 A and  421 B are preferably configured to allow the clinician to grip the distal end of handles  421 A and  421 B with the pinky, ring, and middle fingers of the dominant hand. In the present embodiment, main housing  420  is composed of thermoplastic such as polycarbonate and is substantially transparent. Construction of main housing  420  using material that is substantially transparent facilitates the visualization by the clinician of body fluids that are aspirated into various portions of main housing  420 , as will be explained in further detail below. If main housing  420  is made of a substantially non-transparent material, such as a substantially translucent or substantially opaque thermoplastic, it may be desirable to include cut-out or other window-type areas in housing  420  to permit the clinician to visualize into various conduits (such as conduit  435 A and  435 B) and/or vacuum chamber  450  during use as will be explained in further detail below. The proximal end of main housing  420 , in this embodiment, has a rounded end that may increase grip stability and comfort in the palm of the user. 
     Main housing  420  includes a main housing cap  429 . Main housing cap  429  includes needle attachment opening  431 , conduit  436 A, and channel  435 A. Main housing cap  429  is formed of substantially transparent thermoplastic such as polycarbonate. However, it will be recognized that main housing cap  429  may be formed of other materials as well, and may be translucent, substantially opaque, or opaque. In the event that main housing cap  429  is not formed of material that is substantially transparent, it may be desirable to form main housing cap  429  with a clear, or substantially transparent, section, such as a window, that would permit a user to visualize contents of channel  435 A while insertion device  410  is in use, in particular to allow user to visualize the presence of fluid from the targeted body space in channel  435 A while aspirating into vacuum chamber  450 . In this embodiment, needle attachment opening  431  is continuous with conduit  436 A, which runs through main housing cap  429 . When main housing cap  329  is mounted onto main housing  420 , conduit  436 A in main housing cap  429  is contiguous with conduit  436 B in main housing  420 . Main housing cap  429  can be affixed to main housing  420  using a variety of suitable methods such as, for instance, ultrasonic welds, epoxy, or resin for a permanent attachment. It will be appreciated that main housing cap  429  may also be temporarily affixed to main housing  420  using clips, screws, or other suitable means. In an instance where main housing cap  429  is temporarily affixed to main housing  420 , it will be recognized by a person of skill in the art that additional seals may be deployed to ensure that conduits  435 A,  435 B,  436 A, and  436 B are substantially air-tight during use such that the necessary pressure differential, as described herein, can be maintained to permit the aspiration of body fluids from the targeted body space. 
     A hollow piercing structure, such as needle  440 , is included in insertion device  410 . Proximal end  440 A of needle  440  is affixed, through needle attachment opening  431  into conduit  436 A of main housing cap  429 . Various methods of affixing needle  440  to main housing cap  429  and main housing  420  will be appreciated, including plastic cement, appropriate epoxy, and ultraviolet cured cement. However, to practice the inventions disclosed herein, it is not necessary that needle  440  be permanently affixed to main housing cap  429  and/or main housing  420 . Indeed, it will be appreciated that in some embodiments of the inventions disclosed herein, it may be desirable for needle  440  be to movably and/or removably attached to main housing cap  429  and/or main housing  420  so that, for example, needle  440  can be changed or for example, the orientation of needle  440  can be altered so that the direction of bevel  441  of needle  440  can be adjusted relative to the orientation of housing  420 . Changes to the orientation of bevel  441  of needle  440  can be particularly useful when adapting insertion device  410  for ambidextrous use or for the personal preference of bevel  441  orientation of a clinician. 
       FIG. 17  depicts the proximal end  440 A of needle  440  terminating within conduit  436 A. It should be noted, however, that proximal end  440 A of needle  440  could be extended into conduit  436 B. With such a design, needle  440  should be configured so that the region around proximal end  440 A of needle  440  includes an opening (not shown) along the shaft of needle  440  that is in communication with the lumen of needle  440 . This opening on needle  440  is oriented to communicate with conduit  435 A to permit the flow of aspirated body fluids from the region of the distal end  440 B of needle  440 , through the lumen of needle  440 , and into conduit  435 A. Such aspirated body fluids would be permitted to flow through conduit  435 A into conduit  435 B and ultimately into vacuum chamber  450 . 
     Insertion device  410  further includes vacuum chamber  450  configured to receive plunger  452 . Vacuum chamber  450  is in communication with conduits  435 B and  435 A such that pressure differential created in vacuum chamber  450  will create a suction passing through conduit  435  into the lumen of needle  440 , to permit the aspiration of fluids through the distal end  440 B of needle  440 . Plunger  452  includes a proximal end  452 A and a distal end  452 B. Handle  454  is positioned adjacent to distal end  452 B of plunger  452 , and connected to proximal end  452 A of plunger  452  by member  456  as shown in  FIG. 16 . Member  456  is offset from the sidewall of plunger  452  by a distance approximately equal to the thickness of the bottom wall of vacuum chamber  450  such that the space between the wall of plunger  452  and member  456  creates a channel into which the bottom side wall of vacuum chamber  450  can fit. In this way, plunger  452  can be drawn in a proximal direction by the proximal movement of handle  454 . At least the top face of member  456  is shaped to match the exterior of housing  420  at the region of vacuum chamber  450 . Member  456  is configured to support handle  454  so that handle  454  can be used to move plunger  452  in a proximal (and distal) direction, as well as to secure plunger  452  in vacuum chamber  450 . Ring  420  can be attached to the proximal end of housing  420  to prevent the movement of plunger  452  out of the proximal end of vacuum chamber  450 . 
     Insertion device  410  is further configured to include guidewire  460 . In this embodiment, the proximal region of guidewire  460  is disposed within guidewire housing  462 , which, in turn, is removably attached to main housing  420  at guidewire housing connector  468 . Guidewire housing  462  may be either rigid or flexible, and may be permanently or removably attached to main housing  420 . Further, as shown in the Figures, guidewire housing  462  may be configured to receive cap  463 . Cap  463  can serve to retain guidewire  460  in guidewire housing  462 , as well as to isolate guidewire  460  from potential contaminants in the surrounding environment. 
     Guidewire  460  spans guidewire feed region  464 . Main housing  420  is configured to receive the distal end of guidewire  460  in conduit  436 . In this embodiment, valve  428  is provided and configured to permit guidewire  460  to pass through it prior to entering conduit  436 . As shown, valve  428  seated in valve seat  444  and held in place at least by main housing cap  429 . Valve  428  is configured to allow guidewire  460  to pass through it prior to entering conduit  436 B. 
     Valve  428  serves in insertion device  410  to prevent the substantial movement of air through conduit  436 B such that the pressure differential created by the proximal movement of plunger  452  in vacuum chamber  450  would be defeated. Preferably, valve  428  would provide an air-tight seal around the guidewire of at least about 300 mmHg of pressure. However, it will be appreciated that the function of the inventions disclosed herein, and specifically the aspiration of fluid from a targeted body space through the lumen of needle  440  and ultimately into vacuum chamber  450 , the inventions disclosed herein could be practiced with a vacuum of more or less than about 300 mmHg pressure, depending on the specific application and design of the insertion tool  410 . It will also be apparent that valve  428  may not be necessary to maintain the necessary vacuum, if the entry to conduit  436 B is sized so that the guidewire itself creates a sufficient seal to substantially prevent the flow of air through conduit  436 B during aspiration. 
     When insertion tool  340  is prepared for use, it may be beneficial to use, depending on the specific application, that guidewire  460  is disposed within needle  440 , with the distal end of guidewire  360  close to distal end  340 B of needle  440 . The tip of the distal end of guidewire  460 , however, should not extend through the distal end  440 B of needle  440 , and should remain clear of bevel  441  of needle  440 . However, when the distal tip of guidewire  460  is placed near the distal end  440 B of needle  440  when insertion device  410  is prepared for use, the user is able to more rapidly advance guidewire  460  into the targeted body space, thus securing access to the targeted body space, as soon as puncture of the targeted body space is confirmed, such as through the aspiration of appropriate body fluids through conduit  435  and/or into vacuum chamber  450 . 
     The insertion device  410  depicted in  FIGS. 19-21  can be used to perform a venous access procedure using the ultrasound-guided modified Seldinger Technique, employing the inventions disclosed herein. When prepared for use, guidewire  460  may be positioned within conduit  436 , with the distal end of guidewire  460  reasonably close to, but proximal to, tip  441  of needle  440 . Such pre-positioning of guidewire  460  in the lumen of needle  440  can assist in the rapid deployment of guidewire  460  into the targeted body space. However, such pre-positioning of guidewire  460  within the lumen of needle  440  is not necessary for the practice of this method, or, guidewire  460  can be prepositioned so that the distal tip of guidewire  460  is distal to valve  428  or even proximal to valve  428 . 
     A clinician grasps insertion device  410  in the dominant hand and an ultrasound probe (not shown) in the non-dominant hand. In particular, the clinician grasps housing  420  of insertion device  310  in the palm of the dominant hand with the pinky, ring, and middle fingers of the dominant hand grasping handles  421 A and/or  421 B. The index finger rests around or against grip  454 , and the thumb rests against the guidewire feed region  464 . The clinician presses the tip  441  of needle  440  against a patient&#39;s skin and uses it to penetrate through tissue. While the clinician is inserting the needle, the clinician uses the ultrasound probe and the image produced by the ultrasound machine to follow the progress of needle  440  as it pierces through the tissue. Also, while the clinician is inserting needle  440  through patient tissue, the clinician uses the index finger of the dominant hand to draw back plunger  352  using grip  354 , thereby creating a suction in vacuum chamber  450 . 
     The suction created in vacuum chamber  450  in turn results in a suction at tip  441  of needle  440  through conduit  435 . Body fluid is drawn from the region around tip  441  of needle  440 , through the needle lumen, through conduit  435  and into vacuum chamber  450 . When the tip  441  of needle  440  accesses and pierces the targeted vein, blood flows through the lumen of needle  440 , into conduit  435 A and  435 B and into vacuum chamber  450 . Visualization of blood in conduit  435 A, conduct  435 B, and/or vacuum chamber  450  indicates to the clinician that the targeted vein has been reached and punctured. It will be appreciated that where this process is applied for the access of targeted body regions other than veins, the appearance of other, appropriate body fluids in conduit  435 A, conduit  435 B, and/or vacuum chamber  350  would indicate that the particular targeted body region had been reached. 
     Once the targeted body region, in this example the vein, has been reached, the clinician stops moving needle  440  forward. The clinician uses the thumb of the dominant hand to press guidewire  460  against protrusion  465  and advance guidewire  460  in a distal direction by repeatedly moving the thumb along the guidewire feed region  464  and over protrusion  465 . As explained above, protrusion  465  may be easily replaced in some embodiments of the inventions disclosed herein with a wheel, button, or other structure in guidewire feed region  464  configured to aid the clinician in advancing guidewire  460  in a distal direction and/or retracting guidewire  460  in a proximal direction. 
     In this manner, the clinician uses the thumb to advance guidewire  460  in a distal direction, through conduit  436  and valve  428  into the lumen of needle  440 , past the tip  441  of needle  440  and into the vein or other targeted body space. Because the access device allows for single-handed venipuncture and insertion, the operator can use ultrasound imaging to visualize the needle tip while it is inside of the vein and the guidewire as it is advanced into the vein. Consequently, the risk of tissue injury diminishes. Furthermore, retaining ultrasound visibility allows the operator to ensure that the guidewire is going into the targeted vein as he inserts it. After the operator inserts the guidewire into the vein to the desired length, the access device is removed while the guidewire remains in place for dilation and catheter, sheath, or cannula insertion. 
     Data evaluating the efficacy of the inventions described herein has been collected in a preliminary study and indicate that the inventions described herein are efficacious for ultrasound guided central venous catheter (“CVC”) insertion. An insertion device according to these inventions and generally corresponding to the embodiment described in  FIGS. 5-7  was tested using the techniques and methods described herein. 
     Resident and attending physicians at an academic medical center were recruited to place a CVC catheter in a right internal jugular vein simulator mannequin using both (1) the standard ultrasound-guided Seldinger technique and CVC kit and (2) the insertion device and methods according to the inventions described herein (the “Invention”). Subjects were observed and timed on their placement of the CVC with each technique, total ultrasound visualization time, success of first cannulation, number of cannulation attempts, and arterial punctures recorded. At the conclusion of their testing they completed a survey on their experience with the insertion device and methods according to the inventions described herein. Continuous data such as time for each technique were compared used a paired Student&#39;s t-test, categorical data using a McNemar test, and ordinal data using a Wilcoxon signed rank test as appropriate. 
     Thirty-six subjects were recruited. Represented specialties included emergency medicine (44%), anesthesiology (33%), and surgery (22%) with a median postgraduate year (PGY) level 3. All subjects had previously been trained in CVC insertion and use of ultrasound with 80.6% having placed greater than fifteen CVCs. Additional details concerning the characteristics of the test subjects are provided in Table 1. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Subjects 
                   
               
               
                 Characteristics 
                 (n = 36) 
                 % 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Age (years) 
                 31.4 
                   
               
               
                 Female 
                 15 
                 41.7 
               
               
                 Specialty 
               
               
                 EM 
                 16 
                 44.4 
               
               
                 Anesthesia 
                 12 
                 33.3 
               
               
                 Surgery 
                 8 
                 22.2 
               
               
                 Postgraduate year (median) 
                 3 
               
               
                 Previous CVC training 
                 36 
                 100.0 
               
               
                 Previous US training 
                 36 
                 100.0 
               
               
                 Previous CVCs placed 
               
               
                  0 
                 0 
                 0.0 
               
               
                 1-3 
                 0 
                 0.0 
               
               
                 4-6 
                 3 
                 8.3 
               
               
                 7-9 
                 2 
                 5.6 
               
               
                 10-12 
                 1 
                 2.8 
               
               
                 12-14 
                 1 
                 2.8 
               
               
                 &gt;15 
                 29 
                 80.6 
               
               
                 Confidence in placing CVCs 
                 4.3 
               
               
                 (mean 5-point Likert scale) 
               
               
                   
               
            
           
         
       
     
     Results of the study showed that mean total procedure time was significantly decreased in the Invention group (97 seconds versus 119 seconds, P&lt;0.0001); mean percent ultrasound visualization time during the procedure was significantly increased using the Invention (31% versus 7%, P&lt;0.0001). There were non-significant trends towards increased first cannulation attempt success (32 subjects versus 29 subjects, P=0.453), decreased venous cannulation attempts (5 subjects versus 3 subjects, P=0.470), and fewer arterial punctures (1 subject versus 0 subjects, P=0.317) when using the Invention. All to subjects surveyed stated they would use Invention in a clinical setting, and 80.6% would prefer the Invention over a standard CVC kit. The results of the study are provided in Tables 2-4. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Result 
                 Standard 
                 Invention 
                 P 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Total Procedure Time 
                 119 
                 97 
                 &lt;.0001 
               
               
                 (seconds) 
               
               
                 Percent US Visualization 
                 7.2 
                 31.1 
                 &lt;.0001 
               
               
                 (percent, %) 
               
               
                 Success of first cannulation 
                 29 
                 32 
                 0.453 
               
               
                 (subjects) 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Result 
                 Frequency 
                 % 
                 P 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Venous cannulation attempts 
                   
                   
                 0.470 
               
               
                 Fewer attempts with Invention 
                 5 
                 13.9 
               
               
                 Fewer attempts with standard 
                 3 
                 8.3 
               
               
                 Arterial punctures 
                   
                   
                 0.317 
               
               
                 Fewer arterial punctures with 
                 1 
                 2.8 
               
               
                 Invention 
               
               
                 Fewer arterial punctures with 
                 0 
                 0.0 
               
               
                 standard 
               
               
                 Would use Invention in clinical setting 
                 36 
                 100.0 
               
               
                 Would use Invention over standard 
                 29 
                 80.6 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 Result 
                 5-point Likert scale 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Invention Ease of Use 
                 4.1 
               
               
                   
                 Invention Ease of Use with US 
                 4.7 
               
               
                   
                 Invention Ease of Use with Initial Access 
                 4.4 
               
               
                   
                 Invention Ease of Use on Repeat Attempt 
                 4.4 
               
               
                   
                   
               
            
           
         
       
     
     Data from the study demonstrated that using the Invention is efficacious and feasible for ultrasound-guided CVC placement. It compares favorably to insertion with standard CVC kits and technique with regards to total procedure time and percent of the procedure under ultrasound visualization. It may allow for safer insertion with fewer venous cannulation attempts and arterial punctures. Despite this study being the first encounter with the Invention, subjects were comfortable with its use and expressed a general preference for it over standard methods. 
     Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of Applicant&#39;s invention. For example, a device and method that facilitates one-handed insertion of not only the guidewire, but also the dilating and catheter components as well. Further, the various methods and embodiments of the insertion apparatus can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa. 
     The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions. 
     The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to fully protect all such modifications and improvements that come within the scope or range of equivalent of the following claims.