Abstract:
An esophageal introducer is provided which facilitates the passage of medical probes into the esophagus or gastric cavity. It consists of an introduced tube  12  made of collapsible elastomeric material  21  with a flexible laminated steel at the bottom  20 . The proximal opening is attached to a bite block  10 . The distal end continues with an extension of the laminated steel  20   a  that tapers to a tip with a 45 degree bend  16 . This extension is covered with elastomeric material  21   a  that overlaps the distal tip creating a flat soft end  19 . Prior to insertion the introducer body is bended 20-30 degrees  17 , the tip is advanced till it makes contact with the posterior pharyngeal wall FIG.  3   a.    
     Further pressure will advance the tip effortlessly, sliding on the posterior esophageal wall that is an anatomic continuation of the posterior pharyngeal wall. FIG.  3   b,    3   c.

Description:
CROSS REFERENCE APPLICATIONS 
     NONE 
     FEDERALLY SPONSORED RESEARCH 
     NONE 
     SEQUENCE LISTING OR PROGRAM 
     NONE 
     BACKGROUND 
     1. Field 
     This application relates to medical instruments used to reach the esophagus through the mouth for diagnostic or therapeutic purposes. 
     2. Prior Art 
     Echocardiography is considered as one of the most significant advancements in medical science of the past century. 
     Nonetheless a consecrated tool in the specialty, it found substantial limitations inherent to the physics of the instrumentation. The resolution of the images, an indispensable feature in the accuracy of any imaging modality, is drastically diminished by the distance of the interrogation point and the ultrasound transducer. The interposition of air also renders the tool useless since ultrasound waves cannot be transmitted through this media. Therefore, obesity, COPD and senile emphysema, are conditions that present an insurmountable challenge to the conventional technology. Patients in the intensive care unit undergoing mechanical ventilation also present outstanding difficulties for the transthoracic echocardiographic evaluation. Trans esophageal echocardiography is a technology that came to overcome the above mentioned limitations and became irreplaceable, in circumstances in which ultrasound images of the heart were required and a conventional transthoracic approach was suboptimal. In addition, new indications came to solidify the need for this technology as are the investigation of valvular vegetations, atrial clots, and the presence of patent foramen ovale in addition to intraoperative monitoring of valvular surgery, precardioversion evaluation, among others. One of the most commonly encountered problems with this technology is the passage of the probe in to the esophagus. A substantial limitation is the physical constraint that requires a bulky shape and size of the distal probe that harbors the ultrasound crystals and mechanical components. 
     The passage of such an element through the orophagyngeal area presents self-evident difficulties. The gag reflex is a life preserving characteristic that makes any attempts to introduce any bulky material into the esophagus a very difficult endeavor. Not unexpectedly, the process of passing of the probe through the throat in to the esophagus is the origin of most the complications of the procedure namely, trauma to the larynx or pharynx, bleeding, pain, abscess formation not to mention the discomfort of withstanding such an unnatural procedure. In an attempt to circumvent these limitations, sedation is included routinely. There is no a particular protocol or method to warrant an easy passage of the TEE probe into the esophagus. The probe is supposed to advance straight down into the mid portion of the posterior pharyngeal wall and then by further pressing on the posterior wall the tip should advance into the esophagus since the posterior pharyngeal wall continues seamlessly with the posterior esophageal wall. This process is tainted, by the fact that the procedure is done blindly since the probe has to pass beyond the line of sight behind the base of the tongue, before entering into the esophagus. In addition, esophageal opening  24 ,  FIG. 4  is a virtual space that only opens up during the deglutition process. Therefore, near 100% of the cross sectional area at the level of esophageal opening  24 ,  FIG. 4  is comprised by glottis  26 , epiglottis  27  and pyriform sinuses  29 . In the usual protocol the transesophageal probe is pushed blindly against a closed esophagus assuming that the tip is positioned medially so it will fall against the esophageal opening. Many times, the patient is called to help by trying to swallow the probe, in very unfriendly circumstances. In addition, a particular disadvantage of transesophageal probes in comparison with gastric endoscopes is that the distal angulation does not follow an even curvature but it has an inflection point caused by the unyielding nature of the rigid case in the distal 7 cm of the probe. This unavoidable physical constrain is the reason of the much more difficult negotiation of the TEE probe into the esophagus. Other techniques used by physicians like using the fingers to manipulate the distal end of the probe or the use of laryngoscopes to visualize the esophageal opening are also used, albeit at the cost of increased discomfort and potential complications for patients and operators. 
     Even more, the introduction of conscious sedation to decrease the anxiety of the procedure adds another component of risk and the more difficult the passage of the probe is, the more sedation is needed. Depending of the level of sedation, the patient loses the ability to defend itself against the aggression of the procedure and cases of tracheal intubation and aspiration have been well documented. Previous attempts have been made to create a device that would facilitate the esophageal intubation for transesophageal echocardiograms, however none of them were able to gain acceptance. 
     Douglas U.S. Pat. No. 4,195,624, filed Jun. 9, 1978, describes a device to facilitate the insertion of an endoscope into the esophagus made of a flexible elastomer and a solid tapered tubular end into which the tip of the probe is inserted. Embodiment only add a tapered end to the endoscope but does not facilitate the location of the esophageal opening and obliges to use a large volume tubular structure as the tool to find the opening which seriously limit the accuracy of the maneuvers when the tip is behind the tongue. 
     Griffith U.S. Pat. No. 5,390,661, filed Feb. 3, 1993, presents an introducer with a pilot member and a coaxially fitting sheath. The first embodiment is a device similar to a medical endoscope steerable fitting into a sheath that can be used as the pilot member. Albeit the steer ability is an attractive feature, the cost makes it a less desirable device. 
     Kawahara U.S. Pat. No. 3,913,565, filed Apr. 25, 1974, describes a guide tube to insert instruments into body cavities. Albeit this device was also for esophageal introduction, is merely a flexible tube to guide an endoscope but does not facilitate the localization of the esophageal opening. 
     Park U.S. Pat. No. 5,279,610, filed Nov. 6, 1992, describes a three component structure with a semi rigid sheath, a coaxial introducer guide and a dilator tip. Again, it does not provide a straightforward method that allows the introducer guide to find the esophageal opening. 
     Pastron US patent application 2013/0006057, filed Dec. 29, 2011, describes a device to keep the mouth open during procedures done through the mouth. It serves as a tongue depressor that goes as far as the posterior aspect of the tongue. However, even though it provides a light source and passage ways for catheters, this does not facilitate the introduction of medical probes into the esophagus. Besides, the device aims to decrease the gag reflex but it places the distal portion thereof on the posterior aspect of the tongue where the gag reflex is mostly located. 
     Karakurum US patent 2008/0103508 A1 filed Nov. 1, 2006, describes an esophageal overtube with a basket at the distal end for retrieval of impacted food bolus. It does not describe an easy way into the esophagus but with an endoscope. 
     Balbierz US patent application 2008/008726, filed Jul. 17, 2008, describes an esophageal overtube that is preferably inserted with the guidance of an endoscope or through a guide wire that itself has to be inserted through an endoscope. Albeit the tube is designed to facilitate the repeated insertion of endoscopes during the same procedure, It still requires an endoscope for its initial insertion. 
     Cole US patent application 2009/0030284A1, filed Jul. 17 2008, describes a large introducer tube as part of an assembly for intragastric procedures. Preferably it has to be inserted with the use of an endoscope, alternatives embodiments include a wire that has to be inserted with an endoscope and then the tube has to have a tapered adaptor to follow the wire. A bougie with a snug fit at the distal end and a umbrella type device at the distal end are ways to introduce the tube without the need of an endoscope, but the difficulties finding the esophageal opening without direct visualization remains unsolved as with prior devices. 
     SUMMARY OF THE INVENTION 
     A simple, non-reusable, economical, easy to build and to use device is provided that allows esophageal access effortlessly at a first attempt, without the need for patient participation in the process. 
     In general, the present device is in essence a collapsible sheath to facilitate the introduction of probes or tubes into the esophagus for medical purposes. 
     The device is a simple structure comprising of three components, a proximal bite block; a device well known to people familiar with the art. A body of flexible and fully collapsible elastomeric tube with a stiff laminated strip component attached at the bottom of the fully collapsible elastomeric tube. This element provides skeletal consistency while allowing great anteroposterior flexibility. A third component, that is the continuation of the laminated strip component, protrudes about 3 cm beyond the distal opening of the fully collapsible elastomeric tube. This strip is covered with elastomeric material. 
     The bite block is attached to the flexible fully collapsible elastomeric tube. It has a smooth tapering towards the distal end with a diameter that allows the passage of most medical instruments used in the trade. The elastomeric introducer tube is fully collapsed while is positioned in the esophagus. Albeit quite flexible is able to maintain its uniform shape thanks to the stiff laminate attached to its bottom, to allow guidance during the passage of medical probes. Thanks to its fully collapsible nature, it has a very low profile. This greatly improves patient&#39;s tolerance and minimizes trauma to the mucosal surfaces. The elastomeric material has to be very flexible and malleable, able to collapse under minor pressure, therefore it does not have radial strength. 
     A particular feature that greatly facilitates the use of this embodiment is the design of the distal component. The laminate strip element in the elastomeric tube continues beyond the distal opening tapering down to a narrow tip. The elastomeric material covering its surface folds over at the tip and creates a cushioned end. This tip makes the initial contact with the posterior pharyngeal wall and then slides down into the esophagus without any maneuvering other than gentle pressure in the proximal end comprised of the bite block. 
     The inclusion of a semi rigid laminate in the embodiment allows great anteroposterior flexibility without possibility of lateral displacement. This feature is essential to secure positioning of the tip in the middle of the posterior pharyngeal wall. A 20-30 degree angle in the mid portion of the fully collapsible introducer tube, allows the tip of the embodiment to traverse parallel to posterior pharyngeal wall behind the tongue, beyond the line of sight and then into the continuing posterior esophageal wall. This advancement is done effortlessly without forcing the patient into any awkward and uncomfortable swallowing attempts. 
    
    
     
       DRAWINGS 
       Figures 
         FIG. 1 a   : Introducer tube and bite block. 
         FIG. 1 b   : Profile of Bite block, introducer tube and Introducer extension. 
         FIG. 1 c   : Introducer extension and bending of introducer tube prior to insertion. 
         FIG. 2 a   : Elastomeric tube cut off detail, showing the steel laminate at the bottom of elastomeric tube and Introducer extension. 
         FIG. 2 b   : Distal Introducer tube view and Introducer extension. Detail of Introducer extension tip showing the angulation of steel laminate tip and overlap of elastomeric material. 
         FIG. 2 c   : Introducer extension detail showing semirigid laminate extension and elastomeric material display. 
         FIG. 3 a   : Oro pharyngeal esophageal anatomy, introducer position at the beginning of the insertion process. 
         FIG. 3 b   : Oro pharyngeal esophageal anatomy, further advancement of introducer during the insertion process. 
         FIG. 3 c   : Oro pharyngeal esophageal anatomy, final introducer position with distal opening at about interarythenoid notch. 
         FIG. 3 d   : Hyperextension of neck with smoothing of oropharyngeal angulation to facilitate passage of probe. 
         FIG. 4 : Glottis and adjacent anatomical structures showing the virtual space slit like esophageal opening. 
         FIG. 5 : Alternative Bite Block Design to latch other tubes. 
     
    
    
     DRAWINGS 
     Reference Numerals 
     
         
           10 —Bite Block. 
           11 —Proximal opening. 
           12 —Introducer Body. 
           13 —Introducer Extension. 
           14 —Distal opening. 
           15 —Introducer Extension tip. 
           16 —Steel laminate distal tip bending. 
           17 —Introducer Body 45 degree bending. 
           18 —Elastomeric material proximal overlap into distal opening. 
           19 —Elastomeric material Introducer Extension tip overlap. 
           20 —Steel laminate strip. 
           20   a —Steel laminate strip extension. 
           21 —Elastomeric material tube with detail. 
           21   a —Elastomeric material covering steel strip extension. 
           22 —Posterior Pharyngeal Wall. 
           23 —Posterior Esophageal Wall. 
           24 —Esophageal opening. 
           25 —Trachea. 
           26 —Glottis. 
           27 —Epiglottis. 
           28 —Interarythenoid notch. 
           29 —Pyriform Sinus. 
           30 .—Latch for endotracheal tube. 
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiment described in the present patent is composed of three elements depicted in  FIGS. 1 and 2 . A proximal rigid structure that is essentially a bite block  10 . a well-known tool to people familiar with the art. It consists of a proximal opening  11 , and a rigid tubular structure connected to the second component that is the fully collapsible introducer body  12 . In addition, the third component or distal introducer extension  13 , conformed by steel laminated strip extension  20   a  and elastomeric material covering the strip extension  21   a.    
     Introducer body or tube  12  is composed of a semi rigid laminate strip  20  attached to the floor of elastomeric material tube  21  with a length of about 15 cm. The proximal end is connected to bite block  10  and proximal opening  11 . It smoothly tapes towards distal opening  14 . Its length can be modified when used for endoscopic procedures that require repeated passages of the endoscope. For this purpose a length of 25 cm is recommended.  FIG. 2 a    shows semi rigid laminate strip  20  at the bottom of introducer tube  12  after cutting a section of elastomeric material  21 . 
     The purpose of semi rigid laminate  20 , is to give structural stiffness to introducer body  12  during the insertion process, and during the passage of medical probes in their way to the esophagus. Steel laminate with a thickness of about 0.020″ and a width of about 0.5″ seem to fulfill the need of stiffness and flexibility to follow the anatomical curvatures during the insertion process. 
     The thickness and young modulus of fully collapsible elastomeric material tube  12 , should be such to allow some deformation during the passage of the probe, but still be able to maintain a tubular conduit shape. Minimizing pressure and friction against the adjacent mucosa. Nitrile rubber with a thickness of 0.031″ and a durometer of 60 seems to meet these requirements. Different materials like latex of silicone can be used as elastomeric elements but nitrile seems to have the best tensile strength and elasticity at a durometer of 60 and thickness of 0.031 inches with a much smaller profile not to mention the absence of allergenic properties. The friction over the surface of the white nitrile is reduced by the use of a dry lubricant like Duraglide R, additional lubricant like silicone based one can also be used. Prior to the insertion of the medical probe ultrasound gel filling the tube lumen, will give a third layer of lubricity to the passage of the medical probe. 
       FIGS. 2 b  and 2 c    depicts in detail the third component or distal introducer extension  13 . This is a continuation of steel laminate  20  forming steel strip extension  20   a . Comprises of, approximately 3 cm of steel strip  20   a . This is covered by elastomeric material  21   a  that overlaps the distal end of laminated strip  19 . The purpose of distal overlap  19 , and bending of steel laminate end  16 , is to increase the tip&#39;s surface and its compliance. This tip will make initial contact with pharyngeal mucosa  22  and then will slide onto posterior esophageal wall  23  as is seen in  FIG. 3 a  3 b   . Elastomeric material  21   a  extents 5 mm proximally inside introducer tube  18 . This will help to keep distal opening  14  flattened, smoothing out the transition from distal tip  15  to elastomeric tube  12 . The flattening of the distal opening is facilitated by thinning the distal edges of elastomeric material  12   a.    
     The length of the introducer from the bite block to its distal tip is about 16-17 cm. other embodiments claim the need for a length of at least 20 cm for esophageal introducers. However, to ensure an uninterrupted passage of an esophageal probe, distal opening  14 , just needs to be at about behind the interarythenoid notch  28 . At this level, once the medical device exits distal opening  14 , it will find a straight vertical passage into esophagus. Introducer extension  13  and posterior esophageal wall  23 , will shape the conduit following distal opening  14  as shown in  FIG. 3 c   . This arrangement will prevent any possible anterior displacement into glottis  26  or even trachea  25 . If the embodiment is to be tried in pediatric patients, then the dimensions should be tailored accordingly. 
     The design of the introducer was based on the anatomical considerations of the oropharyngeal structures. Previous assemblies did not take in to consideration the crucial fact that esophageal opening  24  at the level of glottis  26  is mostly a virtual space,  FIG. 4 . Therefore, since esophageal opening  24  is a slit like virtual space, the best design that would better negotiate through this space, with minimal trauma, would be a thin strip element. Introducer extension tip  15  has this particular feature. It slides effortlessly into the esophagus as shown in  FIGS. 3 a    to  3   c.    
     Alternative Embodiments 
     Steel laminate  20  may be modified to increased thickness to provide more consistency that may be needed in condition where the neck cannot be hyperextended or there is crowding of devices in the oral cavity like in trauma patients. 
     Elastomeric tube  20 , may be extended all the way to the tip of introducer extension  13 . The edges should be thinned out assiduously to avoid scratching of the mucosal surfaces. 
     In cases in which the neck cannot be extended a superior location of the steel laminate  20 , instead of an inferior placement as described above may facilitate the advancement of a medical device by providing a hard surface to push against during the introduction. 
     The bite block design can be modified to accommodate other tubes and catheters that may be used concomitantly.  FIG. 5  This can be done by extending the wings on the sides and adding latches for other tubes or probes in use. Also if the device is used for gastric interventions the use of an attachment to proximal end  11  that contains a valve and a connection to insufflate air can be used. 
     Method of Use and Advantages 
     The utilization of this embodiment greatly facilitates the process of reaching esophageal opening  24 . The handling of the introducer is made quite easy by holding the proximal end that is indeed a bite block  10 , a device commonly used in the trade. Prior to the insertion, the collapsed introducer body  12  is angulated about 20-30 degrees mid-way  17 . Then, it is introduced in the midline of the throat and then gently pushed on posterior pharyngeal wall  22 , always maintaining the mid line position  FIG. 1 a   . Introducer extension tip  15 , will come in contact with the pharyngeal mucosa  22 , below the upper level of the posterior tongue beyond the line of sight,  FIG. 3 a   . In the absence of any anatomical deformities that would otherwise be evident by simple visual inspection or by history, further pressure in bite block  10  will inevitably advance introducer extension tip  15 , into esophageal opening  24 ,  FIG. 3 b   ,  FIG. 3 c   . Another particular advantage of this embodiment is its high flexibility, since the pressure applied proximally will be buffered distally by the bending of introducer tube  12  minimizing the pressure against pharyngeal mucosa  23  as the tip slides into esophageal opening  24 . Incidentally, the current standard of care is an essentially blind introduction of esophageal probes by observing the endoscope only up to the level of the throat, or the upper level of the posterior tongue. However, in the case of TEE probes, by design the distal 7 cm harbors the ultrasound crystals and the mechanical components, therefore is rigid and thick. This feature makes the passage into esophageal opening  24 , quite challenging. Furthermore, by design the distal end of the transesophageal probe hinges in multiple directions. This makes the guidance before entering the esophagus even more difficult, with the need to reorient the probe as needed, many times with the operator fingers. 
     If the maneuver is done with a bite block already in place, then the manipulation of the endoscope or probe is done completely blind. 
     Misplacement or bending of the probe will not be recognized except by the inability to advance it upon further pressure. 
     This esophageal introducer departs from prior attempts in the art to create a facilitator to pass medical devices into the esophagus more specifically trans esophageal probes. A fully collapsible elastomeric material tube, without any radial strength  21  and steel laminate  20  with minimal volume allow this introducer to have a minimal cross sectional area in contrast to previous attempted devices. Its malleability and the softness of the elastomeric material make it the most gentler to the mucosal surface. 
     Introducer extension  13 , was designed to effortlessly negotiate down posterior pharyngeal wall  22  and slide into esophageal opening  24 ,  FIG. 4 ; without the need for visual endoscopes or more sophisticated devices. Its construction is simple, its use easy and its cost economical. 
     Once the introducer has been advanced into the esophagus, the patient is still able to talk and relate any discomfort; the easiness of the passage of the device obviates the needs for deeper levels of sedation that increases the risk of the procedure. Even more, in completely sedated or under general anesthesia patients its use is quite convenient since patient participation is not required. 
     Prior to positioning the embodiment in place, the lumen of the elastomeric tube is generously lubricated with ultrasound gel. Then the tee probe or gi endoscope is introduced. The former has the disadvantageous construction with 7 cm of a stiff distal end that makes difficult the negotiation of the angulation between the floor of the mouth and the pharynx. This process is helped by 2 maneuvers. A simple elevation of the chin by 30 degrees and elevation of the head to get a sniffing position. This will reduce the anatomical curvature from 90 to about 60 degrees  FIG. 3 d    facilitating the advancement of the distal end. Another maneuver is to pull back the bite block 1-2 cm proximally when resistance to passage is found, then the probe is advanced 1-2 cm; and subsequently both are advanced together into the esophagus.