Patent Publication Number: US-2020289156-A1

Title: Introducer and methods of use thereof

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to devices and methods for the introduction of medical instruments or objects into a patient. Specifically, the present disclosure relates to devices and methods for controlled introduction of a medical instrument into a surgical site on a patient. 
     BACKGROUND 
     Laparoscopic instruments are traditionally introduced via set ports that pass through the skin and fascia in order to access the desired operative site. The placement of such ports is traditionally achieved by first creating a pneumoperitoneum, and then inserting a port with a trocar or similar device. 
     Insertion of initial trocars and ports, subsequent trocars, needles, and other surgical tools can result in complications, such as port scars, hernias at insertion points, and trauma to the abdominal wall. The use of set ports during a surgery also limits the ability of a surgeon to select the optimal insertion point for an instrument, and requires larger incisions which the surgeon must suture or otherwise close after completion of the surgery. Additionally, existing methods of inserting medical instruments into a surgical field may result in accidental over insertion into the surgical site resulting in damage to internal structures. 
     The present disclosure overcomes one or more of these problems, and/or other problems in the art. 
     SUMMARY 
     A method of inserting an instrument into a patient includes supplying pressurized fluid to an introducer to an instrument introduction site, and advancing an instrument located in the introducer through the introduction site after an initiation of supplying of pressurized fluid. 
     According to another aspect, a medical instrument introducer includes a housing having a proximal end and a distal end, and an instrument support supporting an instrument from the proximal end to the distal end. The introducer also includes an instrument drive assembly having a drive actuator to incrementally advance the instrument through the housing. 
     A medical instrument introducer includes a housing having a proximal end and a distal end, and an instrument support supporting an instrument from the proximal end to the distal end. The introducer also includes a pressurized fluid supply assembly, an instrument drive assembly having a drive actuator to incrementally advance the instrument through the housing, and an exit port at the distal end of the housing, the exit port receiving both the instrument and pressurized fluid from the pressurized fluid supply assembly. 
     It may be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features claimed. 
     As used herein, the terms “comprises” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that “comprises” a list of elements does not necessarily include only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. The term “exemplary” is used in the sense of “example,” rather than “ideal.” 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and together with the description, serve to explain the principles and operation of the disclosed embodiments. Any features of an embodiment described herein (e.g., device, method of treatment) may be combined with any other embodiment, and are encompassed by the present disclosure. 
         FIG. 1  shows a schematic view of an exemplary introducer device in accordance with the present disclosure. 
         FIG. 2  shows an exemplary drive assembly of the introducer device of  FIG. 1 . 
         FIG. 3A  shows another exemplary drive assembly of the introducer device of  FIG. 1 . 
         FIG. 3B  shows an exemplary introducer device. 
         FIG. 3C  shows another exemplary introducer device. 
         FIG. 4  shows yet another exemplary drive assembly of the introducer device of  FIG. 1 . 
         FIG. 5  shows a partial cross section view of the distal end of the introducer device of  FIG. 1 . 
         FIG. 6  is a flow chart of exemplary steps of a method in accordance with the present disclosure. 
         FIGS. 7A-7C  illustrate certain exemplary steps of the method of  FIG. 6 . 
         FIG. 8  shows yet another exemplary introducer device. 
         FIG. 9  shows yet another exemplary introducer device. 
         FIG. 10  shows yet another exemplary introducer device. 
     
    
    
     DETAILED DESCRIPTION 
     The present application relates to embodiments of an introducer for the incremental introduction or retraction of an instrument into or from a desired location. The introducer could be used to introduce any appropriate instrument, for any type of application, in any environment. For example, the introducer could be used for the incremental introduction or retraction of a medical instrument into or from a surgical site on a patient (adult, pediatric, adolescent and/or geriatric). The embodiments provided herein will be explained with respect to the introduction of medical instruments, but it is understood that the introducer is not limited to such medical uses. The device as described may also be used in many existing veterinary procedures. Reference now will be made in detail to aspects of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. 
     The term “distal” refers to a portion farthest away from the operator when introducing an instrument into a subject. By contrast, the term “proximal” refers to a portion closest to the operator when placing the instrument into the subject. The following description refers to the introduction of medical instruments. As used herein, a “medical instrument” may include any type of instrument or device that is used in a medical procedure, regardless of the particular use purpose, specialty, or size of the instrument. For example, the medical instrument may be a laparoscopic instrument, such as a mini-laparoscopic instrument, a needle, sensor/chip, catheter, transfusion device, drain tube, biopsy needle, and/or devices containing fluids, etc. The medical instrument may also be an introduction port, such as a trocar, to provide an accessway for one or more additional medical instruments, or for the simultaneous introduction of instruments with the introduction port. Such an introduction port could be a regular port (such as 5, 10, 12 mm) or smaller. While reference is made in this specification to medical instruments having generally straight shafts, it is understood that bent or curved instruments may also be used with the disclosed introducers. 
       FIG. 1  shows a medical device introducer  10  in schematic form. The introducer  10  includes a housing  12  having a proximal end  14  and a distal end  16 . A distal cap  18  may be located at the distal end  16  of the introducer  10 . A medical instrument  20  is supported within the introducer  10  and is coupled to an instrument drive assembly  22 . The instrument drive assembly  22  includes a drive actuator  24  and incremental drive linkages  26 . The introducer may also include a fluid supply assembly  28 , including a pressurized fluid supply  30 , a valve assembly  32 , and a fluid conduit  34  that may run to the distal end  16  of the housing  12 . The distal cap  18  may include a coupling end  36  for coupling with the tissue of a patient, and a passage  38  for receiving the medical instrument  20  and a supply of fluid from the fluid supply assembly  28 , for allowing both the medical instrument  20  and the pressurized supply of fluid to exit through a distal opening in the introducer  10 . As shown in  FIG. 1 , the drive actuator  24  may extend on both sides of a handle  40 . The valve assembly  32  may be provided at a central location of the proximal end  14  of the housing  12  so as to be positioned for use by both left and right handed users. 
     The housing  12  may receive a shaft of the medical instrument  20  as well as a part or all of the instrument drive assembly  22  and the fluid supply assembly  28 . The housing  12  may be any of a variety of shapes and sizes. Housing  12  may include, for example, a cylindrical shape as shown in  FIG. 1 , or may have a rectangular open frame configuration ( FIGS. 2 and 3 ) to allow for ease of loading and removal of the medical instrument  20  before, during, and/or after introduction. Thus, the housing  12  may fully enclose a portion of the medical instrument  20 , or partially surround the medical instrument  20  with an open frame ( FIGS. 2 and 3 ) to allow for quick removal of the medical instrument  20  from the housing  12 . The shape of the housing  12  may have contouring, for example, to allow for ease of grip by a user, or to fit more ergonomically into a surgical field. The housing  12  may be made in a variety of sizes, based on, for example, the size of the medical instrument  20  to be inserted by the introducer  10 , the size of the drive assembly  22 , and/or ease of handling or use. In another embodiment using various inserts with the device, it may also be possible to use the same introducer device for various sizes of instrument. For example using an insert kit it may also be possible to use instruments from 2, 3, 4, 5 mm and including the larger size devices. 
     As best shown in  FIGS. 3-5 , the housing  12  may have one or more instrument supports to support the medical instrument  20  from the proximal end  14  to the distal end  16 . The handle  40  of housing  12  may be configured as a stationary pistol grip, as depicted in  FIG. 1 . The housing  12  may optionally be constructed in multiple parts, with at least one openable seam running from the proximal end  14  to the distal end  16 , such that it may be separated for accessing the medical instrument  20 . Alternatively, the housing  12  could be a closed structure with a securable door member (not shown) that would allow for connection/access/removal of the medical instrument  20 . 
     The proximal end  14  of the housing  12  may be located proximate to the user or operator of the introducer, and the distal end  16  may be located closest to the tissue of the subject. The distal cap  18  is located at the distal end  16  of introducer  10 . The distal cap  18  may be constructed as a contiguous part of the distal end  16 , or may be a separately constructed part. The distal cap  18  may be a single unit or may divide in order to allow for its removal after introduction of the medical instrument  20 . The distal cap  18  may cover the entire distal end  16 , and may be coupled to the distal end  16  either removably or permanently. For example, distal cap  18  may be removably connected to distal end  16  by a peg-in-groove rotational coupling  17  ( FIG. 1 ), by a threaded connection, by adhesive, or otherwise. With such a removable distal cap  18 , the housing  12  could be a reusable component while the distal cap  18  could be single-use only. Removal of the housing  12  from the medical instrument  20  may include any appropriate connection, for example, a series of dovetail connections  115  and  117  ( FIG. 5 ). The proximal end  14  of a frame-type housing  12  ( FIGS. 2 and 3 ) may be removed from the medical instrument  20  (and separated from housing distal end  16 ) by sliding the frame-type housing  12  along lateral dovetails connections  117  formed with distal end  16 . Thereafter, the remaining distal end  16  of housing that encircles the medical instrument  20  can be removed from medical instrument  20  (after disconnection from distal cap  18  as described above) by sliding opposite mating portions of distal end  16  along axial dovetails  115 . With such a removal process, seal  114  may remain on medical instrument  20  and be removed as desired. Alternatively, the distal cap  18  may be retained in position on the patient to provide support for the medical instrument  20 , or for introduction of a different medical instrument  20 . 
     The medical instrument  20  may be any medical instrument or device having an elongate shaft for introduction into a patient. Examples of suitable instruments  20  include laparoscopic instruments, laparoscopic cameras, trocars, cannulas, wires, interventional radiology devices, stents, stent introducers, substance introducers, catheters of all sizes and rigidities, or fluid tubes. 
     In another embodiment when introducing an instrument or device, the instrument or device could be surrounded by a sheath that would be advanced together with the instrument or device. This sheath could serve several functions, such as to allow for fluid to be delivered at the tip of the instrument or device being introduced, act as a port if left in place. This could potentially allow for the removal of the instrument and the subsequent re-introduction of the same or of another instrument or device. The sheath could also allow for the placement at its tip or on a tip of a medical instruments  20 , one or more sensors to monitor, for example, pressure, or pH, etc. The sheath could also allow for the placement at its tip of a small blade or cauterization device that would incise/cut tissue with each advancement allowing for an easier introduction of the instrument or device. A sheath could also serve to protect the medical instrument  20 , such as a laparoscopic grasper, scissors or camera. 
     An exemplary grasper is schematically illustrated in  FIG. 1 . A medical instrument  20  for use in this disclosure may have an elongate shaft suitable for passing through the introducer  10  and into a surgical site, or may be inserted into a carrying shaft (not shown) for better compatibility with the introducer  10 . 
     The instrument drive assembly  22  is configured to incrementally advance the medical instrument  20  towards and through the distal end  16  of the introducer  10 . The instrument drive assembly  22  may have an instrument drive actuator  24  and incremental drive linkages  26 . A variety of instrument drive assemblies  22  may be suitable for use in the introducer  10 . For example, the instrument drive assembly may be manually powered, electrically powered, pneumatically powered, hydraulically powered, or otherwise. Further, the instrument drive assembly be manually triggered, or may be automatic. Examples of different configurations for drive assembly  22  are depicted in  FIGS. 2-4 . 
       FIG. 2  depicts a first exemplary embodiment of the drive assembly  22 , in which the drive assembly  22  is manually powered and manually triggered. A side, cross-sectional view of a part of the housing  12  is depicted. In this embodiment, actuator  24  includes manual trigger  44  pivotably coupled to handle  40  and arranged to abut a spring-biased tab  48 . Examples of triggers could also be smaller (similar to that found on firearms), or could be a button near the grip site (similar to joysticks and computing gaming), or further could include a three-finger actuator, such as those used to actuate syringes. Other possible triggering mechanisms could be foot activated (such as with a pedal), or remotely activated (as in the case of robotic surgery where the activation would take place at a console). 
     As shown in  FIG. 2 , teeth on a linear rack  50  interlock with teeth on the tab  48 . Both the tab  48  and the rack  50  are depicted with opposing angled teeth. The rack  50  is coupled to the shaft  21  of the medical instrument  20  with, for example, a releasable clip  54 . A clamp or other type of coupling mechanism may be used in lieu of a clip  54 . In an alternative arrangement, a proximal end or rack  50  could include an abutment that would contact the proximal end of medical instrument  20  to push the medical instrument  20  distally. Upon the trigger  44  being actuated towards the handle  40 , as indicated by arrow  59 , the trigger  44  pushes the tab  48  towards the distal end  16  of the introducer  10 . The tab  48  compresses a spring  58  as it moves toward the distal end, and engages the angled teeth of the rack  50 . The rack  50  and coupled medical instrument  20  are therefore pushed towards the distal end  16  of the introducer  10  with the tab  48 . Upon release of the trigger  44 , the trigger  44  and the spring-biased tab  48  return to their original positions due to pressure from the compressed spring  58 . The angle of the teeth on the tab  48  and the rack  50 , together with the pressure from the compressed spring  58 , allow the tab  48  to disengage from the rack  50  when returning to its original position, leaving the rack  50  and the coupled medical instrument  20  in an incrementally advanced position. In this embodiment, an incremental advancement distance for the medical instrument  20  may be determined by, for example, the “throw” length and position of the trigger  44 , the length and resistance to compression of the spring  58 , and/or the size of the teeth on the tab  48  and the rack  50 . 
     In addition or alternatively, drive assembly  22  may include a rotational drive component  23  ( FIG. 2 ) for rotating the medical instrument  20 . According to one aspect of the disclosure, the rotational drive component  23  may be actuated with trigger  44 , however, it is understood the rotational drive component  23  may be separately actuatable. If associated with trigger  44 , rotational drive component  23  may include any conventional structure for converting liner to rotational movement. Thus, according to one aspect of this disclosure, actuation of trigger  44  can actuate both incremental linear advancement and incremental rotation of medical instrument  20 . Alternatively or additionally, the rotational drive component  23  may include, a manual knob, or other mechanism coupled to the medical instrument  20  to allow for selective rotation of the medical instrument  20  by the user. Rotating the medical instrument  20  during introduction assists in movement of the medical instrument  20  through the tissue. For example such rotation would assist the introduction of a trocar incorporating laparoscopic devices. The introduction of a trocar or other similar device provides a mini port that allows for the re-introduction of other medical instruments  20 , such as flexible and semi-flexible catheters. When introducing a trocar with the introducer  10 , a camera may be provided in the trocar lumen to provide for visualization during port placement. 
       FIG. 3A  depicts a second embodiment of a manually powered and manually triggered instrument drive assembly  60 . A side, cross-sectional view of an open frame housing  62  is depicted. A manual trigger  64  is coupled to a handle  66 , and abuts an advancement bar  68 . Handle  66  may have left and right parts  66  (only one shown) with the trigger  64  sandwiched therebetween. The advancement bar  68  includes an opening  70  for passage of the medical instrument  20 , and is coupled to the housing  62  by an angling spring  74 . Upon the trigger  64  being pulled proximally, as indicated by arrow  71 , the advancement bar  68  has an end  76  that is pushed towards the distal end  78  of the housing  62  while a spring  74  restricts proximal movement of an end  79  of the advancement bar  68  opposite end  76 . The angling of the advancement bar  68  causes the shaft  21  of the medical instrument  20  to be secured with the edges of the opening  70  in the advancement bar  68 , thereby gripping the shaft  21  of the medical instrument  20  and advancing the instrument  20  toward the distal end  78 . Upon release of the trigger  64 , the advancement bar  68  loses securement on the medical instrument  20  and returns to its original position, leaving the medical instrument  20  in an incrementally advanced position. A brake bar  80 , located at the proximal end  81  of the housing  62 , also includes an opening  82  through which the shaft  21  of the medical instrument  20  passes. A spring  72  angles the brake bar  80  and opening  82  to provide a grip on the shaft  21  of the medical instrument  20  to prevent unintended movement of the medical instrument  20  away from the distal end  78 , when the advancement bar  68  is not coupled to the shaft  21  of the medical instrument  20 . The brake bar  80  may be pressed distally, compressing the brake spring  72  and eliminating the gripping action of the brake bar  80  on the shaft  21  of the medical instrument  20 , allowing for a manual pushing or pulling movement of the medical instrument  20  when the advancement bar  68  is not gripping the shaft  21  of the medical instrument  20 . 
       FIG. 3B  depicts an introducer device  300  similar to the introducer device  10  of  FIG. 1 , and drive assembly  60  of  FIG. 3A , with common reference numbers being used to identify the same or similar elements. Introducer device  300  includes a stroke limiter  310  having, for example, a threaded bolt  312  extending through brake bar  80  and brake spring  72 , and threadingly engaging housing  62 . Stroke limiter  310  has a distal end  314  (shown in dashed lines) that abuts a top end of trigger  64  to limit forward motion of the bottom end of trigger  64  (i.e., counter-clockwise motion of trigger  64  in  FIG. 3B ). Turning/rotating threaded bolt  312  controls the axial position of the distal end  314 , which controls the stroke length of trigger  64 , thus adjusting the movement of shaft  21  of medical instrument  20  for each trigger actuation. It is understood that stroke limiter  310  need not include the threaded bolt  312 , but could include any other appropriate element or elements to limit the travel of trigger  64 . 
     The introducer device  300  of  FIG. 3B  may also include a shaft securing device  318 . Shaft securing device  318  may include a rotating plate that blocks the medical instrument  20  from being radially removed from housing  62 . Housing  62  may include a series of aligned radial grooves  322  (located on the introducer device  300  opposite the side shown in  FIG. 3B , and indicated with dashed lines) extending to a centerline of the device  300 . Similarly aligned radial grooves are also included in brake bar  80  and advancement bar  68 . The aligned radial grooves allow the medical instrument  20  to be radially inserted into and removed from housing  62 . Shaft securing device  318  is rotatable about an axis parallel to medical instrument  20 , to block or unblock a portion of radial groove  322  in housing  62 . When unblocked, the medical instrument  20  can be introduced or removed from housing  62 . When blocked, the shaft securing device  318  assists in ensuring that medical instrument  20  remains properly positioned within the radial grooves  322 . It is understood that shaft securing device  318  can be any type of device that closes a portion of the radial grooves to help secure the medical device  20  in place. 
     The introducer device  300  of  FIG. 3B  may be configured to include a distal cap  330  similar to distal cap  18  of the introducer device  10  of  FIG. 1 , except that fluid conduit  34  may directly couple to distal cap  330  rather than run through housing  62 . Thus, fluid conduit  34  may couple to the valve assembly  32  and fluid supply outside introducer device  300 . It is understood that valve assembly  32  may alternatively be formed as part of distal cap, and can be controlled in any appropriate manner. 
     Distal cap  330  may be secured to housing  62  in any appropriate manner, such as the peg-in-groove coupling disclosed with respect to the introducer device of  FIG. 1 . Distal cap  330  may alternatively be coupled to housing  62  with a ball-and-socket type connection, such that the distal cap  330  may swivel and rotate with respect to housing  62 . Such a ball-and-socket connection may include a ball element (not shown) protruding from housing  62 , and a mating locking cap and end cap (not shown) on the proximal and distal sides of the ball, respectively (and/or vice versa). The locking and end caps can be, for example, threadingly engaged allow both sliding and locking of the ball between the locking and end caps. Alternatively, the locking cap can include a slot to limit movement of the distal cap  330  relative to the housing  62  only along the slot axis. 
       FIG. 3C  depicts an introducer device  400  similar to the introducer device  300  of  FIG. 3B , with common reference numbers being used to identify the same or similar elements. Introducer device  400  includes a drive rod  410  that is coupled to the medical instrument  20  via a releasable clip  412 , similar to the coupling described with respect the embodiment of  FIG. 2 . Drive rod  410  is driven by an advancement bar  68  in a similar manner as the drive assembly  60  of  FIG. 3A . 
       FIG. 4  depicts another alternative embodiment of the instrument drive assembly  22  of  FIG. 1 . This embodiment considers that the drive mechanism can be powered from a mains supply (at line voltage or stepped down by a transformer), battery power pack or other similar power supply to drive the instrument the requisite incremental distance. The drive mechanism also incorporates a safety override to prevent accidental over-introduction, examples of such sensing may occur from closed loop feedback, pressure sensing or other suitable methods. In this embodiment, an introducer  100  includes an automated drive assembly  84 . The drive assembly  84  is schematically depicted in a cross-sectional side view in  FIG. 4 . The automated drive assembly  84  may be in a housing  86  that may split in half to facilitate loading or unloading of the medical instrument  20 . A plurality of holding rollers  90  are configured to hold the medical instrument shaft  21  and allow for smooth advancement. At least one driving roller  92  is connected to a driving motor  94  which is controlled by an actuator  96 . In  FIG. 4 , the actuator  96  is represented by a button, but may be in any form that can activate the driving motor  94 . The rollers  90 ,  92  may be engaged or disengaged from the shaft of the medical instrument  20  by means of a roller engagement mechanism, controlled by, for example, a roller engagement button  98 . Additional idler rollers (not shown) may be included to aid in keeping the shaft  21  of the medical instrument  20  appropriately positioned, and allow for smooth advancement of the medical instrument  20  towards a distal end  102  of the housing  86 . 
     A variety of configurations of driving rollers, holding rollers and idler rollers are possible, depending on the medical instrument  20  intended for use in the housing  86 . In this embodiment, the mechanism to measure or control the incremental advancement of the medical instrument  20  may be determined by, for example, a fixed time of delivery of power to the driving motor  94  each time the actuator button  96  is pressed. The fixed time may be set, for example, by an increment adjustor button or dial (not shown) on the device itself. Alternately, the actuator button  96  may directly activate the driving motor  94 , such that the user may control the advancement distance by pressing the actuator button  96  for the desired amount of time. The driving motor  94  may be powered using a direct connection to an electrical outlet, or may be battery-operated to allow for more freedom of movement during use of the introducer  100 . Further, the actuator button  96  may power both the driving motor and the fluid supply assembly  28 , such that activating the actuator button  96  may release a desired amount of fluid and subsequently or substantially simultaneously advance the medical instrument  20 . Even further, driving motor  94  may be reversible so that the medical instrument  20  may be withdrawn if desired. 
     The embodiment of  FIG. 4  may also include a driving motor  94  with pressure-sensing capabilities. As such, the driving motor  94  may be able to sense the pressure acting on a medical instrument  20  as it progresses through tissue layers, for example, in the abdomen, to the peritoneal layer. This pressure sensing capability may have several uses. For example, a medical instrument  20  that is being incrementally inserted by a medical introducer  100  according to this disclosure will experience a rise in pressure while traversing the peritoneal layer. Once the medical instrument  20  passes through the peritoneal layer, the pressure on the medical instrument will reduce. By sensing these changes in pressure through the driving motor  94 , an introducer  100  according to  FIG. 4  may be able to sense that the medical instrument  20  is under little or no pressure and is therefore inserted into the abdominal cavity. As another example, pressure-sensing capabilities in the driving motor  94  could be used to sense when the medical instrument  20  has collided with tissue within the surgical site. An introducer  100  according to this embodiment may be linked to or equipped with an alert system, such as a display screen, a light, or an audible alert, to notify the user of the introducer  100  that the medical instrument  20  is inserted into the abdominal cavity, or that medical instrument  20  has collided with tissue within the surgical site. In another embodiment other sensors such as pH, oxygen monitoring, temperature monitoring and other such sensing could also be introduced using the introducer device. 
     Referring back to  FIG. 1 , and as noted above, introducer  10  according to the present disclosure may include a fluid supply assembly  28 , comprising a pressurized fluid supply  30 , an valve assembly  32 , and a fluid conduit  34  from the valve assembly  32  to the distal end  16  of the introducer housing  12 . The fluid supplied by the fluid supply assembly  28  may be any surgically compatible fluid, such as a non-combustible gas (e.g., carbon dioxide) or a sterile liquid (e.g., saline). In another embodiment the surgically compatible fluid could include therapeutic fluids/gels/other substances; some examples include local anesthetic agents, local pain relief and hemostasis substances. 
     Pressurized fluid supply  30  may be connected to the housing  12  through the valve assembly  32 . The valve assembly  32  may comprise a manual control valve including a manual actuator  110 , and a two-position valve body  33  biased toward a closed position (shown in  FIG. 1 ). Upon actuation of the actuator  110  the valve body  33  moves to an open position and pressurized fluid from the fluid supply  30  enters the fluid conduit  34  and supplies pressurized fluid to the distal end  16  of the housing  12 . The valve assembly  32  may be a manually-activated mechanical button as shown in  FIG. 1 , or may comprise an electronic valve assembly. The system may supply pressurized fluid under constant or variable pressure. 
     As best seen in  FIGS. 1 and 5 , fluid conduit  34  runs from the valve assembly  32  through the housing  12 , to the distal end  16  of the housing  12 , where it joins with a passage  38  in the distal cap  18 . Alternatively, fluid conduit  34  could be formed with a separate tube (e.g., a rubber or plastic tubing) running outside the housing  12  and extending from valve assembly  32  to a connection at the distal end  16  of housing  12 . In a further embodiment where the device is used outside the hospital (for example in battlefield hospital) there may also be a requirement for the device to include a self-contained gas (such as a CO 2  cartridge) or liquid supply. When air is used as a gas to assist with incising, a bulbous hand pump may be attached to the trigger  40 . With each activation of the trigger  40  the gas is transmitted to the required location. 
     In one embodiment, towards the distal end  16  of introducer  10 , the conduit  34  widens to become a conduit for both the instrument  20  and the pressurized fluid, such that the shaft  21  of the medical instrument  20  and the fluid pass through the same conduit  34  at the distal end  16 . A seal  114 , such as an o-ring seal, may be located at a proximal portion  35  of conduit  34 , prevents fluid in the conduit from exiting the conduit  34  at the proximal entry point of the medical instrument  20  into the conduit  34 . In addition or alternatively, the medical instrument may include a seal (not shown) about its shaft to assist in sealing the fluid passage. The fluid conduit  34  may be coaxial with the conduit for the medical instrument  20 , as depicted in  FIG. 5 . Further, portions of fluid conduit  34  may be exterior to the housing  12  of the introducer  10 , until it enters the housing  12  near the distal end  16  of the housing  12  and creates a conduit for both the medical instrument  20  and the pressurized fluid supply. This conduit may also surround the instrument and extend into the tissues. 
     As noted above, the introducer  10  according to the present disclosure also includes a distal cap  18  at the distal end  16  of the housing  12 . The distal cap  18  may include a distal coupling end  36  for coupling with the outer tissue (e.g., skin) at a surgical site of a subject. The coupling end  36  may be configured to couple to the tissue of the surgical site in a manner that allows the user of the introducer  10  to pull the outer tissues up and away from the inner tissues. For example, the coupling end  36  may be coated with a waterproof biocompatible adhesive suitable for attaching to skin. As another example, the coupling end  36  may be coupled to tissue with one or more manually-operated tissue clamps positioned around the flange  37 . As a third example, the coupling end  36  may include one or more openings  111  fluidly connected to a suction supply  112  to create a suction-type connection with the skin. Openings  111  in coupling end  36  may include suction cups to better isolate the suction pressure. While coupling end  36  is shown in  FIG. 1  as being circular, it is understood that other shapes are possible, such as an “X” shape with each branch of the “X” having a suction opening  111 . Alternatively, the coupling end may include a series of ring shaped grooves separated by protruding rings forming a bulls-eye configuration. Alternating rings could be connected with suction supply  112 . By applying suction to separate sections of the coupling end  36 , the potential for the leakage of positive or negative pressure is lessened. According to one aspect, applying additional vacuum bursts with each actuation of trigger  40  would allow better contact with the skin and less potential for accidental detachment. 
     The distal cap  18  of the introducer  10  also may include a passage  38  for receiving the medical instrument  20  as it passes out an exit port at the distal end  16  of the introducer  10 , as well as the fluid supply from the fluid supply conduit  34 . For example,  FIG. 5  depicts a distal cap  18  with a centered passage  38  that continues from the fluid conduit  34  in the housing  12 , and that ends in a distal opening of the introducer  10  through which both the medical instrument  20  and fluid from the fluid supply  30  may pass to exit the introducer  10 . A further embodiment of this system is that it could also be developed as an attachment for robotic devices where for example the robotic arm approaches the patient. A suction end  36  that attaches to the skin and instruments are automatically introduced. 
       FIG. 6  depicts a method for advancing a medical instrument into a surgical site in a controlled manner. According to a first step  120 , a predetermined volume of fluid may be set, and may be based on parameters relevant to the surgery, surgeon and/or patient. The volume of fluid may be preset, or may be variably set by the operator. As noted above, the fluid may be a biocompatible noncombustible gas known in the art (e.g., carbon dioxide), or may be a biocompatible liquid. In step  140 , a predetermined advancement distance for the medical instrument  20  into the surgical site may also be set, and may be based on parameters relevant to the surgery, surgeon and/or patient, and/or on the predetermined volume of fluid. The advancement distance may also be preset, or may be variably set by the operator. For example, in some laparoscopic procedures, a predetermined advancement distance may be between 2 and 4 millimeters. The distance advanced may also be regulated by the pressure (or other) sensor at the tip of the instrument. The addition of a monitoring imaging or sensory device (such as an ultrasound or a chip) able to identify intra-abdominal viscera (such as intestine, spleen, liver) and blood vessels, and to distinguish it from the abdominal wall, would provide for a more safe device since it would incorporate an automatic safety mechanism to avoid further advances of the instrument if such structures are not displaced by the bursts of fluid/air. 
     In step  160 , a preliminary incision may be made in the tissue at the instrument introduction site. The preliminary incision may be made by using a small blade on the medical instrument introducer  10 , or optionally using a separate, suitable surgical instrument known in the art. Alternatively small blade or lancet may be incorporated in the introducer that activated to make the initial incision (similar to mechanisms used to obtain a drop of blood to measure glucose levels in diabetic patients). Another variation would include having the blade advance together with the instrument, and cutting the tissues with each triggering. 
     The introducer  10  may then be applied to the tissue at the instrument introduction site (step  180 ). For example,  FIG. 7A  depicts the introducer  10  being applied to tissue at a surgical site. Application of the introducer  10  to the tissue at the site may include coupling the introducer to the tissue at the instrument introduction site by means of an adhesive such as a biocompatible adhesive, medical tissue clips, or other means known in the art, as described above. Once secured to the tissue, the introducer  10  may be used to lift the outer tissue at the introduction site away from the inner tissue (step  190 ), allowing for more space to be created underneath the outer tissue. 
     A predetermined volume of fluid may then be supplied through the introducer  10  into the preliminary incision at the instrument introduction site (step  200 ). For example,  FIG. 7B  depicts the introduction of fluid through the medical introducer  10  into the surgical site. The medical instrument  20  may then be advanced by the previously set predetermined distance through the introducer  10  and the preliminary incision (step  210 ). Step  210  may be carried out after completion of supplying of the predetermined volume of fluid (step  200 ) or may be carried out merely after initiation of the supply of fluid. For example,  FIG. 7C  depicts the advancement of a medical instrument  20  through the medical instrument introducer  10  and the preliminary incision. Following insertion of the medical instrument  20  into the surgical site by the predetermined distance, the predetermined volume of fluid may be reapplied through the introducer and the medical instrument may be further advanced by the predetermined distance repeatedly, until the medical instrument is inserted to the desired depth and/or position. It is understood that the present disclosure is not limited to a method requiring all of the steps of  FIG. 6 , but rather, certain identified steps may be omitted, and/or other steps added. 
       FIGS. 7A-7C  further depict a method of introducing a medical instrument  20  into a surgical site using an introducer  10 . The distal cap  18  of the introducer  10  is brought to a preliminary incision in a patient&#39;s outer tissue  212  at a surgical site. The coupling end of the distal cap  18  is brought into contact with the outer tissue  212 . As previously described, the coupling end may be adhered or affixed to the outer tissue  212  by a variety of means. Referring to  FIG. 7B , a pre-set amount of fluid is introduced through the central passage  38  into the preliminary incision. The introduced fluid may create a new space between the outer tissue  212  and underlying viscera  214  adhering to the outer tissue  212 , as depicted in  FIG. 7B , or may enlarge a preexisting space between the outer tissue  212  and underlying viscera  214 . Referring to  FIG. 7C , the medical instrument  20  is then advanced by a pre-set distance into the space created or maintained by the fluid. Variations on the above-described introducer and method will be evident to those of ordinary skill in the art. 
       FIG. 8  depicts an introducer device  800  similar to the introducer device  300  of  FIG. 3B , with common reference numbers being used to identify the same or similar elements. Introducer device  800  includes a drive assembly  810  having a rotating cam  820  and a clamp  830  coupled for movement with trigger  64 . The rotating claim  820  may be rotated into contact with the medical instrument  20  by manual manipulation via a dial or button located outside the housing  62 . 
     Clamp  830  is coupled to trigger  64  through a rod  840  and plate  850  rigidly coupled to clamp  830 . Upon actuation of trigger  64 , a top end of trigger  64  contacts and moves plate  850  distally, which in turn moves rod  840  and clamp  830  distally. Upon movement of the clamp  830  distally, a ramp  860  of the clamp  830  slides on a ramp  870  of housing  62 , and urges the clamp  830  toward medical instrument  20 . The clamp  830  engages and moves medical instrument  20  if the rotating cam  820  has been moved into contact with the medical instrument  20 . However, if the rotating cam  820  is in the position shown in  FIG. 8 , then distal (or proximal) movement of clamp  830  will not move medical instrument  20 . Thus, the rotational position of the rotating cam  820  dictates whether the clamp  830  moves the medical instrument  20 . In such an arrangement, the rotating cam  820  can be positioned to move medical instrument  20  distally or proximally depending on whether the trigger is moving plate  850  distally, or allowing plate  850  to move proximally due to springs  74 . 
       FIG. 9  depicts an introducer device  900  similar to the introducer device  800  of  FIG. 8 , with common reference numbers being used to identify the same or similar elements. Introducer device  900  includes a plurality of forward motion cams  930 , and a plurality of rearward motion cams  940 . The forward and rearward motion cams  930  and  940  are secured to housing  62 , and movable radially with respect to the housing  62 . Springs  950  and  960  urge forward and rearward motion cams  930  and  940  radially outward. A plurality of clamps  910  and  920  are rigidly coupled to rods  840  and plate  850  to move with the actuation and release of trigger  64 . Upon proximal or distal movement of plate  850 , rods  840 , and clamps  910  and  920 , forward or rearward motion cams may be actuated manually (depressed radially) to secure clamps  910  or  920  on medical instrument  20 , and thereby move medical instrument  20 . Thus, depending on when the cams  930  or  940  are actuated during the movement of plate  850 , the medical instrument  20  can be moved proximally and/or distally. 
     The introducer device  900  may also include a stroke limiter (not shown) protruding inwardly from the housing  62  to limit movement of plate  850 . Further, releasable locking mechanisms (not shown) may be incorporated into forward and rearward motion cams  930  and  940  to further control movement of the medical instrument  20 . 
       FIG. 10  depicts an introducer device  1000  similar to the introducer device  900  of  FIG. 9 , with common reference numbers being used to identify the same or similar elements. Introducer device  900  includes a plurality of motion cams  940  secured to housing  62 , and movable radially with respect to the housing  62 . Springs  960  urge motion cams  940  radially outward. A plurality of clamps  920  are rigidly coupled to rods  840  and plate  850  to move with the actuation and release of trigger  64 . Upon proximal or distal movement of plate  850 , rods  840 , and clamps  920 , motion cams  940  may be actuated manually (depressed radially) to secure clamps  920  on medical instrument  20 , and thereby move medical instrument  20 . Thus, depending on when the cams  940  are actuated during the movement of plate  850 , the medical instrument  20  can be moved proximally and/or distally. 
     Further additions to and variations on the medical introducers and method disclosed herein are possible. For example, the introducers in any of the embodiments described herein may include an imaging device, such as an ultrasound probe, to allow for even safer incremental advancement of a medical instrument  20 . Additionally, any of the above embodiments may further include a safety catch, valve, or switch, to prevent accidental injection of fluid, overpressurization, or advancement of the medical instrument beyond what is desired. Further, any of the above embodiments may be used or performed in combination with added lubrication for easier access to the surgical site, provided by flushing saline through the introducer and into the site, or by the separate addition of sterile lubrication to the site. The above may also provide thermal changes, such as freezing and cauterizing. Introducers according to this disclosure may be single-use devices, or may be created so as to be reusable. The embodiments described herein can be used independently of other laparoscopic introduction tools, such as trocars or ports, or can optionally be used in combination with trocars, ports and/or other surgical instruments. 
     While this patent introduces a new version of technology, the introducer  10  will also complement existing laparoscopic techniques. For example, in cases where additional instruments may be required or would make the procedure simpler or quicker, introducing such instruments with the introducer  10  would make it more acceptable to the surgeon (and of more rapid implementation) since no additional ports will be required. 
     The invention according to this disclosure may exhibit a variety of features. For example, a controlled burst of fluid, when introduced in the abdominal cavity, may dissect away potential viscera or adhesions from the abdominal wall as well as from the instrument  20 . This dissection may occur with or without a pneumoperitoneum in place; in the latter case, obviating the need for a pneumoperitoneum and increasing the safety of the surgery to the patient. The controlled burst of fluid may also decrease resistance imposed by the abdominal wall when attempting to reach difficult-to-access sites. Furthermore, the introduction of a pre-set volume of fluid and the advancement of a medical instrument  20  by a predetermined distance using the introducers and methods described herein may avoid uncontrolled or accidental pushing of a medical instrument into the abdominal cavity (or other surgical site), thus avoiding associated injuries to viscera and structures in the area of the surgery. 
     The devices and methods described herein also may result in the elimination of traditional ports and trocars for laparoscopic procedures, allowing for, for example, flexibility in surgical approach. Where a surgeon might traditionally have been limited to a small set number of immobile ports for a laparoscopic procedure, the devices and methods described herein allow for the creation of numerous ports in various positions, allowing for easier surgical access to desired sites with minimal added strain and risk on the patient. The elimination of port restrictions may also decrease interference, pushing, or collisions between various instruments being used simultaneously in the surgical field. The elimination of port restrictions may make laparoscopic techniques easier and safer, the approach could also facilitate both therapeutic and diagnostic procedures. The present system and method using fluid dissection may reduce the number of port scars associated with larger, set ports. Also, the present system and method may reduce the occurrence of hernias developing at the instrument (or trocar) insertion points, and decrease trauma to the abdominal wall. Additionally, the elimination of a need for a large port or trocar enables the use of smaller diameter medical tools (i.e., only the medical instrument and no surrounding port or trocar) having to be inserted into the surgical site. The insertion of a smaller instrument, and lower numbers of instruments, may mean a lower risk of injury to the patient, a less invasive surgical procedure, and/or a lower cost procedure. The insertion of a smaller instrument may also mean that once the medical instrument is withdrawn, no closure of a large port-created wound is required. 
     Another feature of the devices and methods herein is that they may expand the potential use scenarios for laparoscopic medical instruments and procedures. For example, a decrease in the complexity of laparoscopic surgeries caused by the elimination of a need for set ports may allow for more advanced, and greater use of, diagnostic laparoscopy. It is also envisaged that future pre-identified laparoscopic procedures could be completed with local anesthesia at locations previously not amenable to these techniques, with a decreased risk of infection, with portable single use, (sterile, disposable devices) with the potential to use imaging devices such as for example ultrasound and cameras used in conjunction with cell phones, laptops or portable computer tablet type devices. Laparoscopy using the devices and methods disclosed herein could be expanded to the diagnosis of various pathologies in intensive (critical) care units, emergency rooms by surgeons and emergency room physicians, in battlefield settings, in rural areas, or in telemedicine, for example. Diagnostic laparoscopy using these devices could be performed as a bedside procedure, under local anesthesia, (especially if spraying the anesthetic agent at the site of the intervention and over the peritoneal surfaces), as only a small sterile field may be required, and closure of the surgical wound may be accomplished simply by withdrawing the medical instrument or instruments, without the need for sutures. The devices and methods disclosed herein could also be used to add laparoscopy to interventional radiology procedures, allowing for hybrid imaging/laparoscopic approaches to radiology, and an expanded spectrum of diagnostic and/or therapeutic interventions. Similarly, laparoscopy could be added to hybrid procedures, endoscopic procedures such as colonoscopies, gastro-duodenoscopies, and ERCP, allowing for a combined endo-exo visceral approach to better outline pathologies and obtain tissue samples. The device could also be considered for use in various interventional radiology procedures, fertility treatment procedures, hybrid procedures (such as endoscopy, interventional radiology), nerve block and other various pain management procedures or could also be considered for cardio-thoracic or orthopedic procedures. The instruments may also be compatible to be used in conjunction with Magnetic resonance, CAT (CT) Scan, Positron Emission Tomography (P.E.T. Scan), Ultrasound and other imaging systems. 
     The devices and methods disclosed herein can also be used as a complement to traditional laparoscopic instruments, as portless instruments introduced according to this disclosure could facilitate the action of classic laparoscopic instruments and techniques. 
     A further feature of the devices and methods described herein is that they may be adaptable to a wide variety of cases and procedures beyond laparoscopic procedures, such as pediatric interventions, ob/gyn procedures, and neurologic procedures (such as operations in small fields, procurement of cells, and spinal access procedures). The devices and methods herein may also be applicable in veterinary procedures. Introducers and methods according to this disclosure may be adapted to introduce a medical instrument into the abdominal cavity, or elsewhere in the body, such as into the reproductive system or the circulatory system. Further, as explained above, the disclosed introducers are configured to be used with a variety of different instruments, and thus is not limited to only introducing a particular instrument. 
     Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. While various examples provided herein illustrate specific types of introducers and methods, one of ordinary skill in the art will recognize that other configurations of a medical instrument introducer, and variations upon the methods described, also may be used. For example, the introducer  10  could insert the medical instrument  20  without the positive pressure or suction pressure described above. Further, any features of an embodiment disclosed herein may be incorporated into any other embodiment.