WO2009025843A1 - Laryngeal airway nerve monitor - Google Patents

Abstract

A laryngeal airway nerve monitor (LANM) is described. The LANM includes a dome; a ventilation tube having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome; and a sheath having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome, and wherein the sheath is configured to receive an endoscope.

Description

LARYNGEAL AIRWAY NERVE MONITOR

Related Applications

This application claims priority to U.S. Provisional Patent Application Serial No. 60/965,450, filed August 20, 2007; U.S. Provisional Patent Application Serial No.

61/067,508, filed February 28, 2008; and U.S. Provisional Patent Application Serial No. 61/080,494, filed July 14, 2008. The entire content of each application is incorporated herein by reference.

Background

The thyroid gland is a highly vascular structure that is located in the neck. It produces hormones that have widespread effects in the body. Removal of this gland, called thyroidectomy, is a commonly performed operation. Thyroidectomy is performed for many reasons, including diagnosis and treatment of tumors, and for control of an over- or under- functioning gland. The technique of thyroidectomy involves division of the soft tissue attachments that hold the gland in place.

The thyroid's location in the neck places numerous important structures in jeopardy during thyroidectomy. The recurrent laryngeal nerve (often abbreviated as RLN) is one of these vital structures at risk during thyroidectomy. This nerve controls motion of the arytenoids cartilages and vocal cords. There is one RLN located on each side of the neck. If this nerve is injured on one side of the neck during the surgery, the patient's voice can be severely impaired, often permanently, and the patient is at increased risk of developing pneumonia ("aspiration"). If the RLN is injured on both sides of the neck, the patient's airway can be impaired, thereby jeopardizing respiration. The recurrent laryngeal nerve is a long thin structure, only about 1.5 mm wide, that ascends from the chest into the neck where it enters the larynx (voicebox) at the cricothyroid joint about 2 cm below the thyroid notch ("Adam's apple"). The nerve is located on the posterior (back) surface of the thyroid lobe on each side, and is usually within millimeters of the thyroid gland capsule. Sometimes the nerve is embedded within the gland or adherent to it, making dissection even more difficult.

Proper dissection of the thyroid gland almost always requires dissection and division of soft tissue attachments within millimeters of the recurrent laryngeal nerve, and sometimes requires the surgeon to divide, manipulate, cauterize, and coagulate tissues directly on or adjacent to the nerve. Hence, the RLN is almost always at risk of injury during thyroid surgery. Similarly any other neck surgery occurring in this area (for example, parathyroid surgery, branchial cleft surgery, cervical esophageal surgery), will include dissection near the RLN, putting it at risk of injury. Clearly, patients benefit when the surgeon can accurately identify the recurrent laryngeal nerve during surgery and avoid injury to it during dissection of adjacent tissues. Therefore, it is of critical importance to avoid injury to the RLN during surgery.

Summary of the Invention The present invention provides advantages over currently used surgical devices and techniques. One advantage pertains to identification and preservation of the recurrent laryngeal nerve during neck surgery. Another advantage relates to airway control and passage of endotracheal tubes. These and other advantages of the device are described below During thyroid surgery, the surgeon must thoroughly remove the thyroid gland without traumatizing the RLN, thereby maintaining normal vocal cord function. Surgeons take many different approaches to this objective.

Some surgeons avoid exposing the nerve, hoping that by staying at some distance from it, the likelihood of injury is reduced. This technique of avoiding exposing the nerve has the frequent disadvantage of incomplete removal of diseased thyroid tissue, which sometimes includes cancer. Other surgeons try to identify the RLN at some point during surgery, and then dissect the thyroid gland away from this the nerve.

In all approaches, however, at some point during the operation a putative RLN may be encountered. It is then desirable to confirm that the structure encountered (the "nerve candidate") is, in fact, the RLN as opposed to fascia, fat, blood vessels, or other tissues that may have a similar appearance. The unique characteristic that distinguishes the RLN from any other structure in the body is that, with electrical stimulation of the RLN, the muscles of arytenoids and vocal cord on the same side of the larynx will twitch. This twitch in most cases cannot be visualized directly in the wound, because the muscles involved are on the posterior (back) side of the larynx, or internal to the larynx.

Instead, surgeons use other techniques to determine whether a nerve candidate is or is not the RLN. The most common techniques are listed below: 1.) The surgeon stimulates the nerve candidate electrically and monitors the laryngeal muscles by palpation for evidence of a muscle twitch. The palpation is done by placing a finger on the muscles on the external surface of the larynx, within the surgical field. 2.) The surgeon stimulates the nerve candidate electrically and monitors the laryngeal muscles electrically for evidence of a muscle twitch by using electrodes. These electrodes are placed at the beginning of the operation, either external or internal to the larynx.

3.) The surgeon stimulates the nerve candidate electrically and monitors the laryngeal muscles visually for evidence of a muscle twitch. The surgeon or other observer looks for motion of the vocal cord through endoscopes passed to the larynx via the mouth. In general, such endoscopes are passed at points during the operation when the nerve is being tested, and then removed, allowing only intermittent monitoring of the nerve. All of these techniques have drawbacks that are avoided and/or overcome by the laryngeal airway nerve monitor (LANM) devices provided by the invention. The LANM devices of the invention permit identification and monitoring of recurrent laryngeal nerve (RLN) function during neck surgery. They allow the surgeon to monitor continuously the vocal cord and/or arytenoids visually, looking for twitches in response to electrical stimulation of the RLN during neck dissection and at the end of surgery prior to removal of the patient's airway. These techniques offer benefits over other approaches in terms of low incidence of false negative and false positive identification rates, continuous monitoring and ease of use. The devices provided by the invention enable a surgeon to perform thyroid and other neck surgery with greater confidence and thoroughness and with decreased risk to the RLN.

It is also important that the surgeon and anesthetist/anesthesiologist know the status of vocal cord function prior to, and at the conclusion of, surgery. The devices provided by the invention permit visualization of the arytenoids and/or vocal cords during patient spontaneous respiration. During spontaneous respiration the vocal cords abduct (move apart) to allow more air to pass. An arytenoid and/or vocal cord that is impaired in its motion by disease or tumor, or the RLN of which is paralyzed for any reason (such as by cancer or by surgical injury) will be immobile during spontaneous inspiration. By contrast, the opposite vocal cord and arytenoids will move normally. By using the devices provided by the invention, the anesthetist/anesthesiologist and surgeon can confirm prior to incision that the patient's arytenoids, vocal cords and RLN have intact function. They can also confirm at the conclusion of surgery that the arytenoids, vocal cords and RLN function normally, or that they do not function normally, and make an appropriate response.

One aspect of the invention provides a laryngeal airway nerve monitor (LANM) including a dome, a ventilation tube, and a sheath. The ventilation tube has a proximal end and a distal end. Each end has an opening. The distal end of the ventilation tube is in communication with the dome. The sheath has a proximal and a distal end. The distal end of the sheath is in communication with the dome. The sheath is configured to receive an endoscope.

In one embodiment, the dome and ventilation tube are configured to receive an endotracheal tube. The LANM can include a connector coupled to the ventilation tubing, the connector adapted to interface with an anesthetic breathing circuit. The connector can be removably coupled to the ventilation tube. The connector can be tethered to the ventilation tube.

In another embodiment, the ventilation tube is flexible, rigid, and/or armored.

In another embodiment, the sheath is coupled to the ventilation tube. The sheath can be coupled externally or internally to the ventilation tube. The sheath can be confluent with the ventilation tube. The sheath and the ventilation tube can share a common point of entry at the dome.

In other embodiments, the LANM includes devices to prevent soft tissue from entering the ventilation tube. For example, the LANM can include a bar spanning the distal opening of the ventilation tube to prevent soft tissue from entering the ventilation tube. The bar can be hinged to allow for passage of an endotracheal tube. Alternatively, the LANM can include a flap covering the distal opening of the ventilation tube to prevent soft tissue from entering the ventilation tube. hi other embodiments, the LANM includes a balloon cuff coupled to the dome. The LANM can also include an inflation tube coupled to the balloon cuff. The inflation tube can be located external to the ventilation tube.

In another embodiment, the dome is configured to dilate a subject's throat.

In another embodiment, the distal end of the sheath extends beyond the dome. For example, the distal end of the sheath can extend between about 0 cm and about 5 cm beyond the dome. In certain embodiments, the sheath can have an internal diameter less than about 2 mm, between about 2 mm and about 10 mm, or greater than about 10 mm.

In another embodiment, the distal end of the sheath is configured to provide a view of a subject's vocal cords when the laryngeal airway nerve monitor is placed in the larynx of the subject.

In another embodiment, the distal end of the ventilation tube extends between about 0 cm and about 5 cm beyond the dome.

In another embodiment, the LANM includes a lens coupled to the distal opening of the sheath. In still another embodiment, the LANM includes a prism coupled to the distal opening of the sheath. In another embodiment, the LANM includes a cap coupled to the proximal opening of the sheath. The cap can be tethered to the sheath. In another embodiment, the LANM includes a flap coupled to the proximal opening of the sheath. In another embodiment, the LANM includes a flap coupled to the distal opening of the sheath. In another embodiment, the LANM includes an endoscope received within the sheath, the endoscope having a proximal and distal end. The endoscope can includes a light source, a camera located at the distal end of the endoscope, and/or an ocular located in the proximal end of the endoscope. The endoscope can also include a first fiber optic cable for the transmission of light from the proximal end of the endoscope to the distal end of the endoscope. The endoscope can further include a second fiber optic cable for the transmission of images from the distal end of the endoscope to the proximal end of the endoscope. The endoscope can also include a channel for the transportation of fluids.

In other embodiments, the endoscope is rigid, semi-rigid, flexible, and/or steerable.

Another aspect of the invention provides a method of protecting a subject's recurrent laryngeal nerve during surgery. The method includes introducing a laryngeal airway nerve monitor into the subject's larynx, introducing an endoscope into a sheath of the laryngeal airway nerve monitor, visualizing the subject's vocal cords with the endoscope, identifying a recurrent laryngeal nerve candidate, stimulating the recurrent laryngeal nerve candidate, observing a movement in the subject's vocal cords with the endoscope, and identifying the recurrent laryngeal nerve candidate as the subject's recurrent laryngeal nerve. The laryngeal airway nerve monitor includes a dome, a ventilation tube, and a sheath. The ventilation tube has a proximal and a distal end. Each end has an opening. The distal end of the ventilation tube is in communication with the dome. The sheath has a proximal end and a distal end. Each end has an opening. The distal end of the sheath is in communication with the dome. The sheath is configured to receive an endoscope.

In one embodiment, the step of stimulating the recurrent laryngeal nerve candidate comprises applying electrical current to the recurrent laryngeal nerve candidate. In another embodiment, the method includes inserting an endotracheal tube through the dome to ventilate the subject. In another embodiment, the laryngeal airway nerve monitor includes one or more inflatable cuffs and the method includes inflating at least one of the one or more inflatable cuffs.

Another aspect of the invention provides a surgical kit including a laryngeal airway nerve monitor (LANM) and instructions for use. The LANM includes a dome, a ventilation tube, and a sheath. The ventilation tube has a proximal and a distal end. Each end has an opening. The distal end of the ventilation tube is in communication with the dome. The sheath has a proximal end and a distal end. Each end has an opening. The distal end of the sheath is in communication with the dome. The sheath is configured to receive an endoscope.

In one embodiment, the surgical kit includes an endotracheal tube adapted for passage through the dome. In another embodiment, the surgical kit includes an endoscope configured for passage through the sheath. In another embodiments, the instructions for use include instructions for performing the method described above. Another aspect of the invention provides a laryngeal airway nerve monitor including a laryngeal mask airway and a sheath. The laryngeal mask airway includes a dome and a ventilation tube. The ventilation tube has a proximal and a distal end. Each end has an opening. The distal end of the ventilation tube is in communication with the dome. The sheath has a proximal end and a distal end. Each end has an opening. The distal end of the sheath is in communication with the dome. The sheath is configured to receive an endoscope.

Brief Description of The Drawings

Various embodiments of the invention will be further explained with reference to the attached drawings, wherein like structures are referred to by like numerals throughout the several views. The drawings shown are not necessarily to scale, with emphasis instead generally being placed upon illustrating the principles of the presently disclosed embodiments.

Figures IA, IB, and 1C depict an embodiment of the invention incorporating a ventilation tube and mask.

Figures 2 A and 2B depict an embodiment of the invention incorporating tubing that allows for the passage and removal of an indwelling endotracheal tube.

Figure 3 depicts an embodiment of an the invention for use when a patient is ventilated exclusively by an endotracheal tube. Figure 4 depicts the interaction of a ventilation tube, connector, and endotracheal tube according to one embodiment of the invention herein.

Figure 5 depicts various configurations of the ventilation tube and sheath according to embodiments of the invention herein.

Figure 6 depicts various configurations of the ventilation tube and the sheath at the entry point to the dome according to embodiments of the invention herein. As illustrated, the sheath can be proximal, distal, lateral, or confluent to the ventilation tube at the point of entry.

Figure 7 depicts various configurations of the distal end of the ventilation tube according to embodiments of the invention herein. Figure 8 depicts various configurations of the proximal and distal ends of the sheath according to embodiments of the invention herein.

Figure 9 A depicts an embodiment of an endoscope according to and for use with the invention herein.

Figures 9B and 9C depict the use of the inventions during neck surgery on a human subject. Figure 9B depicts the exterior of the human subject, while Figure 9C depicts the distal end of the laryngeal airway nerve monitor device as received in the larynx of the subject.

Figure 10 depicts a method of protecting a subject's recurrent laryngeal nerve during surgery.

Detailed Description

The following detailed description of certain embodiments of the invention is provided with reference to the accompanying drawings. The LANM devices of the invention are advantageously used during any neck surgery that involves dissection near the RLN and/or that puts the RLN at risk of injury during dissection and/or any surgery that involves the risk of difficult endotracheal intubation. Examples of such surgery include, but are not limited to, thyroidectomy, parathyroidectomy, branchial cleft surgery, neck dissection, cervical esophageal surgery, carotid surgery, and sleep apnea surgery. A description of the device follows.

The invention provides various device embodiments and variations of these embodiments. Various embodiments of the device include three components: a.) a laryngeal mask airway component; b.) an endoscopy sheath component; and c.) an endoscope component.

Laryngeal mask airways are widely used devices for maintaining and controlling respiration during general anesthesia. The function of a laryngeal mask is to create a closed system connecting the patient's respiratory tract with the anesthetic system allowing controlled inflow and outflow of anesthetic and patient gases. The LANM, like other laryngeal masks, comprises ventilation tubing, a dome and a balloon cuff. The ventilation tubing connects the anesthetic tubing to the device. The dome connects that tubing to the balloon cuff. The balloon cuff seals the laryngeal mask against the lining of the patient's throat preventing leak of anesthetic gases from the throat during ventilation. The LANM features a laryngeal mask that incorporates an endoscopy sheath. This sheath permits passage of an endoscope into the distal end of the laryngeal mask, thereby providing laryngeal visualization without impairing ventilation.

In one embodiment, shown in Figure 1 , the laryngeal mask is the sole method of ventilation of the patient during surgery. It is intended for use in patients who will not require or receive an endotracheal tube for ventilation during surgery.

In another embodiment, shown in Figure 2, the laryngeal mask is one method of ventilation of the patient during surgery. It is intended for use in patients who may need or receive ventilation via an endotracheal tube during some portion of the surgery and a laryngeal mask for the remainder of surgery. In yet another embodiment, shown in Figure 3, the laryngeal mask is not used for ventilation, but merely as a conduit for the endoscope and endoscope sheath. It is intended for use in patients who will receive ventilation through an endotracheal tube for the entire surgery. As noted above, various embodiments of the device can include three components: a.) a laryngeal mask airway component; b.) an endoscopy sheath component; and c.) an endoscope component.

Each component will be described in detail, with reference to the accompanying Figures.

Laryngeal Mask Airway Component

Certain embodiments of the invention incorporate a laryngeal mask airway. A laryngeal mask airway comprises a tube which is indwelling in the patient's pharynx. It provides a conduit for ventilation during general anesthesia, carrying gases between the ventilator and the patient's lungs. An endotracheal tube also provides such a conduit. The major difference between the laryngeal mask airway and the endotracheal tube is that the laryngeal mask airway tubing ends proximal to (above) the level of the vocal cords during anesthesia and the endotracheal tube ends distal to (below) the vocal cords. Different benefits and risks are present in using laryngeal mask airways as compared to endotracheal tubes. Sometimes an anesthetist or anesthesiologist will seek to pass an endotracheal tube in a patient who is already being ventilated through a laryngeal mask airway, for example to obtain a better pneumatic seal during ventilation. Typically this requires removal of the laryngeal mask and replacement with an endotracheal tube. Removal of the laryngeal mask and placement of the endotracheal tube is a two step process than can be cumbersome and time consuming. Furthermore, in the time between removal of the laryngeal mask airway and placement of the endotracheal tube the patient is not being ventilated and is not breathing. In this event, the patient would benefit from a laryngeal mask that would allow passage of an endotracheal tube while the patient was still being ventilated through the laryngeal mask. Some devices, such as those available under the LMA-FASTTRACH® and CTRACH® trademarks from LMA North America of San Diego, California, currently permit the insertion of an endotracheal tube. However, such devices are not intended for long term insertion or reversible ventilation of the patient by laryngeal mask airway and endotracheal techniques, and cannot be used for ongoing nerve monitoring during neck surgery. For example, such devices incorporate relatively hard and/or stiff plastics and metals that are more likely to cause scratches, irritation and ulceration of tissues if left in place for an extended period of time than the more flexible plastics used in indwelling tubes.

As mentioned above, there are three major methods of RLN monitoring currently in use-the first two methods generally employ an endotracheal tube, and the third method generally uses a laryngeal mask airway. Some patients are not amenable to the third technique, such as those with large compressive thyroid masses. These patients often need a rigid endotracheal tube to stent the trachea in the region of the large thyroid mass, preventing compression and obstruction by the mass. This need may not always be apparent at the beginning of surgery, but may become more obvious over time, or with swelling or bleeding of the mass, or pressure from dissection.

In such cases the surgeon or anesthesiologist may decide to "convert" from a laryngeal mask airway to an endotracheal tube at some point during the procedure. If these patients are anesthetized using a laryngeal mask airway alone, and subsequently need an endotracheal tube, the process of switching from the laryngeal mask to the endotracheal tube can be time consuming and cumbersome. This can be hazardous to the patient as he/she is not receiving ventilation (or anesthesia) during the conversion from one airway to another.

The LANM devices of the invention overcome the foregoing problems by permitting passage of an endotracheal tube while keeping the laryngeal mask portion of the device in place. This enables the anesthetist/anesthesiologist to insert an endotracheal tube and gives the patient the benefits of the endotracheal tube without the disruption and loss of airway that would be associated with removal of the laryngeal mask. Furthermore, because the laryngeal mask remains in place, the anesthetist/anesthesiologist can insert and remove the endotracheal tube multiple times during the operation as needed, depending on whether the patient needs the benefits given by a laryngeal mask airway or an endotracheal tube at different points in the operation and anesthesia administration.

The devices also permit passage of an endotracheal tube under direct visualization of the vocal cords. The anesthetist/anesthesiologist is able to pass the endotracheal tube with better control than would occur without adequate vocal cord visualization, thereby reducing the risk of laryngeal injury or loss of airway control that can occur from incorrect or traumatic endotracheal tube passage. LANM devices of the invention allow airway management with less disruption in a system that also allows continuous nerve monitoring during neck surgery.

The laryngeal mask airway component 100a of the LANM preferably is constructed of standard medical grade plastic or rubber tubing 102a, a dome 104a, and a standard flexible balloon cuff 106a which surrounds the dome 104a and seals off the throat creating a closed, controlled system. The laryngeal mask airway component 100a may be made of reusable or disposable materials. The shape of components 100a, 102a, and 104a are different in embodiments described herein as dictated by their interaction with any endotracheal tube present. The variations of a first embodiment depicted in the Figure 1 and described herein are equally applicable to the embodiments of Figure 2 and Figure 3 and are accordingly not depicted again for brevity.

For all embodiments, the tubing 104 is of variable length and diameters as is the case with standard laryngeal masks, it may be flexible or stiff and may be armored for reinforcement. In armored tubing, one or more strands of a protective material are incorporated either internal, external, or within the tubing to provide additional strength and kink resistance. Suitable materials include, but are not limited to, metals such as stainless steel or Nitinol. ("Nitinol" is an acryonym for Nickel Titanium Ordnance Laboratory".) This variety of dimensions permits use of the device with a range of patient sizes from infants to large adults.

In the embodiments of Figure 1 and Figure 2, the tubing 104, 204 may connect to the anesthetic tubing via a connector 114, 214 and can be used for ventilation. In the embodiment of Figure 3, the tubing 302 is not used for ventilation as the patient is ventilated through the endotracheal tube during the entire surgery. In the embodiment of Figure 1, the tubing 102 is similar in design to that found in current laryngeal mask airways. In the embodiment of Figure 2 (the version designed to permit endotracheal intubation) the tubing 202 is of a diameter sufficient to allow passage of any of a variety of endotracheal tubes sizes ranging from 2 to 9 mm in internal diameter without pinching or binding of the endotracheal tube to the walls of the tubing 2. In the embodiment of Figure 3, the tubing 302 is large enough in diameter to slide easily over an endotracheal tube tubing.

In the embodiments of Figure 1 and Figure 2, one end of the tubing 102, 202 includes a connector 114, 214 which permits attachment with standard anesthetic breathing circuits. As illustrated in Figure 4, this connector 114, 214 may be removed to allow passage of endotracheal tubes 218. The connector 114, 214 may be attached to the tubing 102, 202 by a tether system 116, 216 to prevent it from becoming misplaced when removed from tubing 102, 202. Suitable tether systems include, but are not limited to string, twine, rope, cables, wire, webbing, chain, and the like.

As depicted in Figure 5, the tubing 102, 202, 302 may be separate from the endoscope sheath 110, 210, 310 or the tubing 102, 202, 302 and endoscope sheath 110, 210, 310 may be confluent prior to entry into the mask dome 104, 204, 304. The tubing 102, 202, 302 and sheath 110, 210, 310 may have any of a variety of shapes, diameters and lengths that allows passage of an endoscope at one point of entry and attachment to the anesthesia breathing circuit at another point. As depicted in Figure 6, the tube 102, 202, 302 and sheath 110, 210, 310 may remain separate, or may then become confluent with a common point of entry 108, 208, 308 into the laryngeal mask dome 104, 204, 304. As depicted in Figure 7, the far (distal) end of the tubing 102, 202, 302 or sheath

110, 210, 310 may have a guard (702, 704) to prevent entry of soft tissues retrograde into the breathing tube (Figure 6). The guard can be of any design that spans the opening of the 102, 202, 302 or sheath 110, 210, 310 in any of a variety of directions or widths such that satisfactory ventilation can still occur and the airway patency is not compromised. In some embodiments, the guard is configured so that if the tubing 102, 202, 302 and endoscope sheath 110, 210, 310 are a common channel, the divider does not prevent visualization of the vocal cords, or prevent passage of the endoscope 220 beyond the divider. One suitable embodiment of the guard 704 acts as a "one way valve" so that the divider will move out of the way to permit passage of the endoscope, but not retrograde into the tubing 102, 202, 302, thereby keeping soft tissue from obstructing the tubing.

The dome 104 is made of medical grade plastic and may be of variable length, widths, thicknesses and curvatures, as is currently the case with standard laryngeal masks, as is appropriate to permit satisfactory fit of adult and pediatric patients of varying sizes. As in current laryngeal masks, the tubing 102 enters the dome 104 at an entry point 108. Unlike current laryngeal masks, the entry point 108 also permits entry of the endoscope sheath 110 or of a common tubing of 102 and 110. The sheath entry point 110 is designed to permit visualization of the vocal cords/arytenoids when the dome 104 is in place during ventilation of the patient. It may be located in the midline or to either side of the tubing 102 and at a range of distances from the any edge of the dome. As described above, sheath 110 may also be a common channel with the tubing 102. More detail on the sheath 110 is described below. In the embodiments of Figure 1 and Figure 2, the shape of the dome 104 is similar to current laryngeal mask airways to permit ventilation but with modification to allow entry of the endoscope sheath 110 as described above. The function of the dome 104 in the embodiments of Figures 1 A-IC and Figure 2 is also to splay and dilate the throat (hypopharynx) in manner that prevents the soft tissues of the throat from collapsing so that they do not obstruct visualization of the arytenoids and/or vocal cords with the endoscope 218. In the embodiment of Figure 2, the distal tubing 202 and dome 204 may have a higher profile than in the embodiment of Figures 1 A-IC. This is designed to permit the retraction of an endotracheal tube end and balloon into the dome 204 as depicted in Figure 2A. In the embodiment of Figure 2, the endotracheal tube cuff 222 and laryngeal mask cuff 206 can be inflated in this position (depicted in Figure 2A), creating a seal and allowing the patient to be ventilated through the endotracheal tube, even though the endotracheal tube 218 is proximal to the vocal cords. This position allows ventilation with wide exposure and viewing of the vocal cords and arytenoids. In the embodiment of Figure 2, the endotracheal tube 218 can be advanced distally while keeping the LANM 200 in place. The endotracheal tube cuff 222 can be placed distal to the vocal cords and inflated and the LANM cuff 208 can be inflated or deflated. This position allows viewing of the arytenoids while simultaneously stenting the trachea during ventilation via the endotracheal tube. In a third clinical condition, the endotracheal tube 218 can be removed entirely from the LANM 200. In this condition the patient can be ventilated by attaching the connector 214 to the tubing 202 and to the anesthetic circuit. The cuff 206 is then inflated and the patient ventilated, in a similar fashion to the embodiment of Figure 1.

In the embodiment of Figure 3, the patient is ventilated entirely through an endotracheal tube 318. The purpose of the dome 304 in such patients is to splay and dilate the soft tissues of the hypopharynx in manner that prevents the soft tissues of the throat from collapsing so that they do not obstruct visualization of the arytenoids and/or vocal cords with the endoscope 320. The balloon cuff 106, 206, 306 is a standard plastic medical grade cuff similar to that currently used in laryngeal mask airways, of variable lengths, widths, thicknesses and volumes, as is currently the case with standard laryngeal masks, and as is appropriate to permit satisfactory ventilation of adult and pediatric patients of different sizes. The cuff is inflated via a standard valved inflation point 112, 212, 312, which may have its point of entry at any point along tubing 102, 202, 302 from close to the connector 114 (as depicted in Figure 1C) to the actual entry point 106 (as depicted in Figures IA and IB).

In the embodiments of Figure 1 and Figure 2, the cuff 106, 206 is similar to that used in current laryngeal mask airways. The embodiment of Figure 3 may or may not include a cuff(s) 306. The role of the cuff 306 in the embodiment of Figure 3 is to permit repositioning of the device through inflation of a cuff 306 or multiple cuffs 306 on the various sides of the dome 304. In embodiments with multiple cuffs 306, one or more valved inflation points 312 can be provided to allow for individual adjustment of one or more cuffs 306. Such individual adjustment allows for both the lateral movement of dome 304 by increasing pressure/volume of cuffs 306 on a first side of dome 304 and/or decreasing presseure/volume of cuffs 306 on a second side of the dome 304. Furthermore, one or more cuffs may be adjusted to adjusted to promote the desired stenting and/or dilation of the larynx.

Endoscopy sheath component

The sheath 110, 210, 310 is made of standard medical grade plastic. It runs approximately parallel to the airway tubing 102, 202, 302 and in one variation may merge with it prior to entry into the dome 104, 204, 304. The sheath 110, 210, 310 functions to permit passage of an endoscope 218 in order to allow visualization of the arytenoids and/or vocal cords during surgery. The sheath 110, 210, 310 material is either rigid or flexible plastic and of a consistency that permits smooth passage of an endoscope without excessive friction. Friction can be reduced by the application of a lubricant to the endoscope 220 and/or the sheath 110, 210, 310 before, during, or after insertion of the endoscope. Suitable lubricants include, but are not limited to, water soluble lubricants such as those sold under the SURGILUB E® trademark by Nycomed US Inc. of Melville, New York. The caliber (internal diameter) of sheath 110, 210, 310 may range from about 2 to about 10 mm to permit passage of the endoscope component 218 without binding. The length of the sheath may vary from about 1 cm to about 30 cm to permit a variety of length and diameter endoscopes 218 to be used. This range of lengths is deliberately wide to permit passage of a variety endoscopes 218 either briefly to allow a single view of the larynx, or permit passage of an endoscope 220 that is left indwelling during the surgery to allow ongoing monitoring throughout the entire operation.

The entry point 108 is designed such that the endoscope sheath 110, 210, 310 enters into the dome 104, 204, 304 sufficiently to permit a satisfactory view of the arytenoids and/or vocal cords. In some embodiments, the sheath extends about zero to about 5 cm beyond the entry point 108, for example: between about 0 cm and about 1 cm; between about 1 cm and 2 cm; between about 2 cm and about 3 cm; between about 3 cm and about 4 cm; and between about 4 cm and about 5 cm. This range is deliberately wide so that the portion of endoscope sheath extending into the dome is sufficient to permit laryngeal visualization without obstruction by adjacent structures such as the epiglottis, or the tubing 102, 202, 302 or cuff 106, 206, 306, and so that the sheath 110, 210, 310 does not extend so far as to lead to an overly narrow field preventing view of glottic aperture or so far as to interfere with the airway. The tubing 102, 202, 302 and sheath 110, 210, 310 may be positioned as they enter the dome 104, 204, 304 in a variety of positions including side to side, front to back, or as a common channel.

The ends of the sheath 110 may have several variations as depicted in Figures 8A-8D:

1.) Figure 8 A: In this variation, the proximal end 802a of sheath 110, 210, 310 is open, as represented by the double-ended arrow. The distal end 804 a of sheath 110, 210, 310 culminates in a plastic or glass end 806 which functions as a neutral lens or a lens that acts as a prism permitting angled viewing. The endoscope 220 when passed through this sheath 110 can view the larynx through this lens 806. The lens 806 also seals off the sheath component 110, 210, 310, preventing leakage of gas from the laryngeal mask dome 104, 204, 304.

2.) Figure 8B: In this variation, the distal end of sheath 110, 210, 310 is open as represented by the double-ended arrow. A lens is not present at the distal end 804b, permitting passage of the endoscope to the sheath's distal end 804b, or beyond, to view the larynx. At the proximal end 802b, a cap 114, 214 may be attached to the sheath 110, 210, 310 sealing off the sheath 110, 210, 310 when the endoscope 220 is not in place.

3.) Figure 8C: In this variation, the proximal and distal ends (802c and 804c, respectively) of the sheath 110, 210, 310 are open, but a flap valve 808 may be attached, which permits passage of the endoscope 220, but which seals closed when the endoscope 220 is not in use, preventing leakage of gas from the laryngeal mask.

4.) Figure 8D: In this variation, the proximal end 802d is open, the distal end 804d is closed with a flap valve 810 which permits passage of an endoscope 220 during inspection of the larynx, but which seals off the sheath 110, 210, 310 when the endoscope is not in use, preventing leakage of gas from the laryngeal mask.

For each of the above embodiments, there are variations in which the sheath 110, 210, 310 may run separately from the ventilation tubing 102, 202, 302, or may merge with it at some point prior to entry into the dome 104, 204, 304.

Endoscope component

The function of the endoscope 220 is to permit visualization of the arytenoids, vocal cords and other muscles of the larynx before, during and/or after surgery. In this manner the surgeon and/or anesthetist/anesthesiologist can determine if laryngeal muscle motion and RLN function is intact. When the RLN is not being stimulated and the patient is not excessively anesthetized, the patient may have spontaneous respiration. This state permits visualization of the patient's normal laryngeal muscle motion, allowing determination of whether both RLNs and vocal cords are functioning normally before and after surgery. During surgery, use of the endoscope 220 permits visualization of the vocal cords and laryngeal muscles during stimulation of the RLN and other structures. This allows determination of whether a nerve candidate is in fact the RLN and whether the RLN is functioning.

Embodiments of the invention may use a wide variety of commercially available endoscopes 220, or a novel endoscope 900 (described herein and depicted in Figure 9A) including but not limited to the following: 1.) One embodiment of the invention incorporates a rigid straight endoscope ranging in width from about 2 to about 10 mm and of a range of lengths from about 1 cm to about 20 cm, with refractory lens angles ranging from zero to 45 degrees. This range permits the use of existing endoscopes as well as a small micro-endoscope that is indwelling in the endoscope sheath 110, 210, 310 and connected to a light source 902 and camera 904 by wires passing through the sheath 110, 210, 310.

2.) Another embodiment of the invention incorporates a rigid or semi-rigid curved endoscope ranging in width from about 2 to about 10 mm and of varied lengths from about 1 to about 20 cm with lens angles ranging from zero to 45 degrees. The curve of the endoscope would conform to the curve naturally present between the patient's mouth and the entry point 108, 208, 308 when the LANM is in place and may permit easier passage than with a straight rigid endoscope.

3.) Another embodiment of the invention incorporates a flexible endoscope ranging in width from about 2 to about 10 mm and of varied lengths. This endoscope may be of the "steerable" or non-steerable variety. This range permits the use of existing flexible endoscopes as well as a specialized endoscope wand 900. This endoscope wand would end in a light source 902 and chip camera 904.

4.) Another embodiment of the invention incorporates standard endoscopes and chip cameras that are currently available for visualizing the vocal cords and/ or larynx.

The endoscope proximal end may consist of an ocular 906 to view the larynx directly or to which a camera 904 may be attached for viewing over a video monitor 908. Alternatively, the endoscope may attach to a cable for attachment directly to surgical monitors 908. hi such an embodiment, a camera (e.g. a chip camera) can be located within the endoscope, such as at the proximal or distal end or intermediate to the proximal and distal ends. The camera may output video signals in a proprietary or standard video format. The endoscope may connect with monitor 908 using proprietary or standard connections such as RF connectors, component video (e.g. NTSC, PAL, or SECAM), S-Video, component video, Serial Digital Interface, Fire Wire, High- Definition Multimedia Interface (HDMI), USB, Ethernet, Gigabit Ethernet, or wireless (e.g. BlueTooth and/or IEEE 802.11). Alternatively, monitor 908 or a video processing unit can be connected to the endoscope by one or more fiber optic strands, which relay an image from the distal end of the endoscope 220. Surgical monitor 908 may take many forms. In some embodiments, surgical monitor is a television or a computer monitor (e.g. a cathode-ray tube (CRT), liquid crystal display (LCD), or plasma screen). In other embodiments, the monitor 908 is a general purpose computer such as a desktop or a laptop. The monitor 908 may be configured or coupled to a device for capturing and/or recording video and/or images transmitted from the endoscope 908.

Surgical monitor 908 may be located in the operating room or in another location. In some embodiments, the surgical monitor 908 is wall-mounted. Additionally or alternatively, the surgical monitor 908 can be a relatively small LCD screen coupled with the tube 102, 202, 302 or other components of the invention. Such an embodiment is advantageous as it allows the surgeon to visualize the vocal cords during the insertion of an endotracheal tube. In other embodiments, the surgical monitor is mounted on a cart so that surgeon or anesthetist/anesthesiologist can easily view the larynx during surgery. This embodiment is advantageous because it overcomes the need to remove the laryngeal mask airway and/or monitor 908 that are coupled with conventional laryngeal mask airways unless the laryngeal mask airway is supported by the anesthesiologist. The invention also provides an endoscope 900 for use with the LANM. The endoscope 900 includes components commonly found in medical endoscopes: a lens 910, a fiberoptic light cable 912 for carrying light from light source 902, a fiberoptic image cable 914 for carrying the optical image to monitor 908. Like some medical endoscopes, one variation of the endoscope 900 includes a channel for suction or instillation of liquids and/or a component for manipulating the distal tip 916 of the endoscope 900. The endoscope 900, chip camera 904, light source 902, and interfaces include a number of variations which would permit either a set of cables connecting the endoscope to the monitor 908 and light source 902, or a lightweight battery operated light source and radiofrequency camera attached directly to the end of the endoscope similar to those currently available. The length of the endoscope may range from about one cm to about 60 cm. This broad range permits either a very small endoscope including the light source 902 and chip camera 908 entirely within in the endoscope sheath 110, 210, 310 or a longer endoscope with the lens 910 and fiberoptic cables 912, 914 in the endoscope sheath 110, 210, 310 and the light source 902 and chip camera 904 external to the sheath 110, 210, 310. The light source 902 may be a standard halogen type light source as commonly used for endoscopes, or a smaller battery powered light source recently developed for portable endoscopes such as one or more light-emitting diodes (LEDs). In some embodiments, the light source is powered by a light weight battery such as a lithium ion battery.

The chip camera 904 may be of a type commonly used in medical endoscopes. The interface between the light source 902 and the fiberoptic cable 912 may be of the standard type of cable used in endoscopes or a connector as commonly used between small battery powered lights and fiberoptic light cables. The interface between the chip camera 904 and the monitor 908 may be a standard type of cable used in endoscopes or may be of a radio frequency transmitting variety currently available commercially.

Advantageously, the light source 902, chip camera 904, and all other components associated with endoscope 900 can be light weight. A light weight endoscope 900 exerts less force on the LAMs described herein and is less likely to move during a procedure than conventional endoscopes which are heavy, bulky, and designed to be held by a human during use.

The endoscope 900 described herein contains several features that are particularly adapted to the LANMs described herein. The endoscope 900 can be specifically designed for smooth passage through sheaths 110, 210, 310.

In one embodiment, the endoscope 900 can have an external diameter smaller than conventional endoscopes such as less than about 10 mm or less than about 2 mm. Additionally or alternatively, endoscope 900 can be coated with a substance that reduces friction such as polytetrafluoroethylene (PTFE). PTFE is commercially available, for example, under the TEFLON® trademark from E.I. Du Pont de Nemours and Company of Wilmington, Delaware. In another embodiment, the endoscope 900 is the optimal length for use with the LANMs, for example between about 1 cm to about 50 cm, which is considerably shorter than conventional endoscopes. Furthermore, the lens configuration of endoscope 900 allows for an optimal view of the vocal cords.

Any of the endoscopes 220, 320, 900 may have any of a variety of systems, clamps, and adhesive straps to hold it in place during the monitoring process or may be inserted for a brief view and removed immediately after viewing.

Use of Various Embodiments of the Invention

It is very important that the surgeon and anesthesiologist know prior to neck surgery whether the patient's arytenoids and/or vocal cords function normally. Currently, the arytenoids and vocal cords are assessed by some surgeons in the office with a mirror exam, or with fiberoptic endoscopy, which can be imprecise or uncomfortable. Many surgeons, including most general surgeons, are not adept in these techniques of laryngeal assessment and do not assess vocal function adequately prior to incision. This can be a problem in a patient who may have a pre-existing vocal cord paralysis, fixation or airway compromise that is not detected prior to surgery.

First, patients who have a single paralyzed nerve rely upon the opposite functioning side for respiration. Injury during surgery or other loss of function of this side jeopardizes the airway. Wakeup from anesthesia in such patients can be hazardous. In addition, if a pre-existing vocal paralysis is not identified prior to surgery, when it is discovered it may be incorrectly deemed a complication of the recent neck surgery.

Furthermore vocal cord paralysis in the setting of a thyroid cancer indicates a worsened prognosis and may require a change in the surgical plan. For all of these reasons, the surgeon and anesthesiologist need to know prior to surgery the level of function of the vocal cords and RLN. The LANM provided herein allows the surgeon and anesthesiologist to assess vocal cord motion prior to neck incision, ensuring that it is normal, or alternatively to be aware that it is abnormal and make appropriate adjustments.

Likewise, it is imperative that the surgeon and anesthesiologist know at the conclusion of neck surgery whether the patient's vocal cords move normally and that the RLN is functioning. Currently this is assessed by some surgeons in the office with a mirror exam, or fiberoptic endoscopy which can be imprecise or uncomfortable. Many surgeons, including most general surgeons, are not adept in these techniques of laryngeal assessment and do not assess vocal cord mobility postoperatively. The LANM allows the surgeon and anesthesiologist to assess vocal cord motion at the conclusion of surgery and prior to wakeup from general anesthesia, ensuring that it is normal, or alternatively to be aware that it is abnormal and make appropriate adjustments to manage a vocal cord(s) that is not functioning adequately. This also permits documentation that vocal cord and RLN function were preserved during surgery, and that any subsequent change in vocal mobility is not attributable to surgery. Also, it is essential for surgeons to know during neck surgery the location of the

RLN. Identification of the RLN allows the surgeon to avoid or minimize manipulation of and injury to, the RLN and increases the chance that it will be preserved during surgery, and its function maintained. Identification of the RLN also permits more complete removal of the adjacent thyroid tissue with less fear or risk of accidental RLN injury.

Some surgeons identify the RLN visually only, i.e. the surgeon assumes that tissue that appears to be the RLN is the RLN. However, this method does not ensure adequate RLN identification because other structures such as blood vessels may have a similar appearance, or they may be identifying only a branch of the RLN. Other surgeons identify the RLN by stimulating the structure with electric current, then monitoring the laryngeal muscles and vocal cord for a response to this stimulation. Suitable electrical stimulation devices are sold under the NEUROSIGN® trademark by The Magstim Company Limited of Carmarthenshire, Wales, United Kingdom. See Michael Hermann, et al., 240 Neuromonitoring in Thyroid Surgery: Prospective Evaluation of Intraoperative Electrophysiological Responses for the Prediction of Recurrent Laryngeal Nerve Injury 9 (2004). Methods for monitoring the laryngeal muscles consist of palpation of the laryngeal muscles for motion, monitoring the muscles for electrical or muscle potentials with electrodes, or visually monitoring the muscles for motion.

The LANM devices of the invention allow monitoring of the muscles visually for motion when the RLN is stimulated. The advantages of the LANM over other systems are as follows: a.) Monitoring of the laryngeal muscles through palpation is imprecise and requires experience to be accurate. Only one person at a time can palpate for a laryngeal muscle twitch preventing verification by others. Proper placement of the palpating finger requires additional dissection to expose the posterior laryngeal muscles. This entails increased surgical time, risk of bleeding and injury to the RLN. If the palpating finger is not in the precise location, the muscle twitch can fail to be palpated (false negative) and the RLN can be inadvertently injured. Placement of the palpating hand and finger often obscures the view of the RLN in the surgical field making accurate RLN stimulation more difficult. If the RLN is weak but intact, the degree of muscle motion triggered by stimulation may not be sufficient to create a palpable twitch, making the technique inaccurate. Also, the palpation technique cannot be employed during minimally invasive or endoscopic approaches to neck surgery, because these approaches do not allow surgical exposure sufficient to palpate the posterior laryngeal muscles. The LANMs provided by the invention are advantageous because they require no additional dissection nor alteration of the surgical field from its state during dissection. Multiple persons can view the larynx for motion during RLN stimulation providing independent verification. Identifying muscle and vocal cord motion does not require experience and can be delegated to any medical personnel, permitting non-surgeons or less experienced surgeons to judge the response to nerve stimulation while the surgeon stimulates the nerve. This is not possible with the palpation technique because both nerve stimulation and muscle palpation require experience, and in most cases two experienced surgeons. If the RLN is weak but intact, diminished vocal cord motion may be visible yet not palpable, therefore, again the risk of inadvertent nerve injury through false negative response is reduced. b.) Monitoring of the laryngeal muscles through electrical or muscle potentials requires placement of electrodes internal or external to the larynx. If the electrodes are not properly placed, or if they shift during surgery, they will provide a false negative result, potentially leading to inadvertent nerve injury. In most techniques currently used, the surgeon will be unaware of a shift of the electrodes, greatly increasing the risk of a false negative response. Proper placement of the electrodes requires additional skill, as does interpretation of the electrical tracings of the electrodes. Improper placement will lead to a false negative result and increased risk of nerve injury. Motion of the larynx and neck during surgery can stimulate the electrodes even through the RLN is not being directly stimulated causing false positive responses. False positive responses cause undue concern over the status of the RLN, slowing surgical speed.

The LANMs of the invention do not require placement of special devices or electrodes. Its design allows easy passage of an endoscope by untrained personnel. While visualization and determination of vocal cord motion requires some medical knowledge, the person doing this interpretation can be the surgeon who views the larynx on a monitor while the endoscope is passed by a nurse, technician, anesthetist or resident. If the endoscope is not in proper place, the poor view will be immediately apparent unlike shifted or unattached electrodes, thereby reducing the false negative rate. False positive rates are not an issue as the vocal cord will not twitch with motion of the neck or larynx. c.) Monitoring of the laryngeal muscles visually with endoscopes has generally required disconnection of the laryngeal mask from the ventilator and passage of the endoscope via this opening into the larynx. This causes wide leakage of the associated anesthetic gases, and simultaneous ventilation of the patient is not possible. As a result, nerve monitoring can only be done for brief periods, because it requires interruption of ventilation. A flexible endoscope can be passed through a side port on the laryngeal mask airway, but existing laryngeal mask airway designs often prevent easy passage of the endoscope or do not permit viewing of the vocal cords because of the location of the opening within the mask airway. The tubing may be too narrow, the bend in the tubing too severe, or plastic components intrude and prevent smooth endoscope passage. Current systems require skill on the part of the personnel passing the endoscope, otherwise the larynx will not be easily and properly viewed.

The LANMs of the invention are designed to permit precise passage of the endoscope to a point within the airway permitting excellent vocal cord visualization, even when done by minimally trained personnel. This is important because the surgeon and anesthesiologist may be otherwise occupied in stimulating the RLN and monitoring the vocal cord for motion. By using the LANMs of the invention, the surgeon and anesthesiologist need not be involved in passage of the endoscope as well. The LANMs' design also permits ongoing monitoring of the larynx during surgery — something that is not possible with existing laryngeal mask airways.

Some surgeons visualize the larynx during neck surgery by placing a laryngeal mask airway above an endotracheal tube, then passing the endoscope down the laryngeal mask airway. In such cases, the laryngeal mask functions as a conduit for the endoscope and is not used for ventilation. Arytenoid motion is monitored with the endotracheal tube in place. This design however, is cumbersome to place as currently available endoscopes are not well suited for passage through laryngeal masks for long periods. Furthermore there are no well designed devices to immobilize the endoscope for the long periods required for surgery. As a result, the devices have to be passed and removed repeatedly during the operation. The laryngeal mask in these cases must be passed either to the right or the left of the endotracheal tube, so the arytenoid and vocal cord on one side are seen better than those on the other side.

The LANMs of the invention, e.g., the embodiment of Figure 3 with endoscope 900 design, permit an indwelling option for laryngeal monitoring in the presence of an endotracheal tube. Because the LANM depicted in Figure 3 tubing 102 is passed over the endotracheal tube 318 like a ring over a finger, the endoscope 320 lies midline and both arytenoids are visualized equally well. The suction channel also permits evacuation of saliva that otherwise pools and obscures the view during surgery. Patients undergoing neck surgery receive general anesthesia through a laryngeal mask airway or an endotracheal tube to connect the patient's respiratory tract with the ventilator. Each of these devices has different risks and benefits. For example, laryngeal mask airways are often superior to endotracheal tubes in ease of insertion, and they permit wakeup from anesthesia with less tracheal irritation and coughing. Endotracheal tubes can stent a tracheal airway narrowed by tumor, and can prevent aspiration of gastric contents in patients prone to reflux. Anesthesiologists are often willing to leave endotracheal tube cuffs inflated for longer periods than laryngeal mask cuffs.

The LANMs of the invention (e.g., the embodiments of Figure 2 and Figure 3) allows the patient to benefit from either airway technique. Because it is a laryngeal mask airway, the LANM (e.g. the embodiment of Figure 2) can be inserted more easily than an endotracheal tube, and without need for laryngeal visualization. This is especially beneficial in a patient whose vocal cords are hard to visualize (such a patient with cervical arthritis, obesity or compressive neck mass). Also, it permits awakening from anesthesia without the irritation of trachea as occurs with an endotracheal tube.

Because the LANMs of the invention also permit visualization of the vocal cords, the anesthesiologist is able to pass an endotracheal tube through the LANM tubing 102, 202, 302 and between the vocal cords under direct visualization of the endoscope 220, 320. This allows the anesthesiologist to pass an endotracheal tube 218, 318 using the LANM at any point during the operation without removing the laryngeal mask and without losing the ability to monitor vocal cords.

For example, a patient with tracheal narrowing could be anesthetized with the LANM, and an endotracheal tube 218, 318 passed under endoscope 220, 320 visualization to stent the trachea during thyroid or neck dissection. At the point the surgeon wishes to test for the RLN, the endotracheal tube 218, 318 can be withdrawn into the tubing 102, 202, 302, and the cuff 222, 322 inflated to maintain a seal. The surgeon can then have a clear view of the vocal cords during stimulation. Usually by this point in the surgery, the mass compressing the airway has been lifted, and the endotracheal tube 218, 318 is no longer needed as a stent. Similarly, if the anesthesiologist seeks to minimize time of cuff inflation with a laryngeal mask, during any portion of the surgery when RLN testing is not needed, the endotracheal tube 218, 318 could be passed and the LANM cuff 106, 206, 306 deflated. In some embodiments, the surgeon or anesthesiologist may prefer to leave the endotracheal tube in place during the entire operation. Using the LANMs of the invention, e.g., the embodiment of Figure 3, the surgeon can test RLN function with an endotracheal tube 218, 318 in place. Although the entire vocal cord is not in view, as it is obscured by the endotracheal tube 218, 318, the arytenoids are clearly seen, and RLN stimulation causes visible twitching of the arytenoids and confirmation of RLN function, even in the presence of an endotracheal tube 218, 318 between the vocal cords.

The LANMs of the invention are also useful in patients not undergoing neck surgery. Some patients may be judged by the anesthesiologist to require an endotracheal tube 218, 318, but their anatomy precludes good visualization of the vocal cords during passage of the tube. Such patients can be anesthetized with the laryngeal mask portion of the LANM, and then an endotracheal tube 218, 318 passed during direct visualization of the vocal cords using the endoscope portion of the LANM. In this manner, the LANM provides an option for passing an endotracheal tube in patients with challenging airway anatomy. Referring to Figures 9B and 9C, a subject 918 is undergoing neck surgery.

Although the subject 918 is depicted as a human, one of skill in the art will recognize that the apparatus and methods provided herein are equally applicable to other subjects such as mammals. A laryngeal airway nerve monitor 100 is positioned in the subject's larynx. Ventilation tube 102 is connected to anesthetic breath circuit 920 for oxygenation, ventilation, and anesthesia.

An incision 922 in the subject's neck allow for the removal of tissue 924, e.g. the thyroid gland. During the surgery, an recurrently laryngeal nerve candidate 926 is identified. The evaluate whether the candidate is actually the RLN, an electric stimulation device 928 is applied to the RLN candidate 926. Suitable electrical stimulation devices are sold under the NEUROSIGN® trademark by The Magstim

Company Limited of Carmarthenshire, Wales, United Kingdom. If the RLN candidate is actually the RLN, the subject's vocal cords will move as observed on monitor 908. Figure 10 is a flow chart illustrating a method of using the invention herein. In Step 1002, a laryngeal airway nerve monitor 100, 200, 300 is introduced into the subject's larynx. At this point or any other time as may be advantageous, one or more cuffs 106, 206, 306 can be inflated to form a seal over the subject's larynx and/or stent the subject's larynx. Oxygenation, ventilation, and/or anesthesia may be commenced as discussed herein.

In step 1004, an endoscope 220, 320, 900 is introduced into the sheath 110, 210, 310 of the laryngeal airway nerve monitor (LANM) 100, 200, 300 (if the endoscope 220, 320, 900 was not introduced before insertion of the LANM into the subject's larynx. In step 1006, the subject's vocal cords 930 are visualized. The vocal cords can be visualized according to any of the components provided herein. For example, an observer may look at an ocular at the proximal end of endoscope 220, 320, 900. Alternatively, the images captured by the endoscope 220, 320, 900 can be viewed on display 908 as described herein. In step 1008, a recurrent laryngeal nerve (RLN) candidate is identified. The

RLN candidate is identified by the surgeon by its appearance and location as informed by the surgeon's experience and by reference to anatomy texts such as Gray's Anatomy by Henry Gray or Atlas of Clinical Anatomy by Richard S. Snell.

In step 1010, the RLN candidate is electrically stimulated, for example, with a NEUROSIGN® 100 nerve monitor available from The Magstim Company Limited of Carmarthenshire, Wales, United Kingdom.

In step 1012, the subject's vocal cords 930 are examined for movement as a result of the electronic stimulus. If the vocal cords 930 do not move, the LRN candidate 926, the LRN is identified (step 1014) and the surgeon dissects away from the LRN (step 1016). If the vocal cords do not move, another LRN candidate is identified (step 1008).

The foregoing specification and the drawings forming part hereof are illustrative in nature and demonstrate certain preferred embodiments of the invention. It should be recognized and understood, however, that the description is not to be construed as limiting of the invention because many changes, modifications and variations may be made therein by those of skill in the art without departing from the essential scope, spirit or intention of the invention. Incorporation by Reference

The entire contents of all patents, published patent applications, and other references cited herein are hereby expressly incorporated herein in their entireties by reference.

Claims

Claims

1. A laryngeal airway nerve monitor comprising: a dome; a ventilation tube having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome; and a sheath having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome, and wherein the sheath is configured to receive an endoscope.

2. The laryngeal airway nerve monitor of claim 1, wherein the dome and ventilation tube are configured to receive an endotracheal tube.

3. The laryngeal airway nerve monitor of claim 1, further comprising: a connector coupled to the ventilation tubing, the connector adapted to interface with an anesthetic breathing circuit.

4. The laryngeal airway nerve monitor of claim 3, wherein the connector is removably coupled to the ventilation tube.

5. The laryngeal airway nerve monitor of claim 3, wherein the connector is tethered to the ventilation tube.

6. The laryngeal airway nerve monitor of claim 1, wherein the ventilation tube is flexible.

7. The laryngeal airway nerve monitor of claim 1 , wherein the ventilation tube is rigid.

8 The laryngeal airway nerve monitor of claim 1, wherein the ventilation tube is armored.

9. The laryngeal airway nerve monitor of claim 1, wherein the sheath is coupled to the ventilation tube.

10. The laryngeal airway nerve monitor of claim 1, wherein the sheath is coupled externally to the ventilation tube.

11. The laryngeal airway nerve monitor of claim 1 , wherein the sheath is coupled internally to the ventilation tube.

12. The laryngeal airway nerve monitor of claim 1, wherein the sheath is confluent with the ventilation tube.

13. The laryngeal airway nerve monitor of claim 1, wherein the sheath and the ventilation tube share a common point of entry at the dome.

14. The laryngeal airway nerve monitor of claim 1 further comprising: a bar spanning the distal opening of the ventilation tube to prevent soft tissue from entering the ventilation tube.

15. The laryngeal airway nerve monitor of claim 14, wherein the bar is hinged to allow for passage of an endotracheal tube.

16. The laryngeal airway nerve monitor of claim 1 further comprising: a flap covering the distal opening of the ventilation tube to prevent soft tissue from entering the ventilation tube.

17. The laryngeal airway nerve monitor of claim 1 further comprising: a balloon cuff coupled to the dome.

18. The laryngeal airway nerve monitor of claim 17 further comprising: an inflation tube coupled to the balloon cuff.

19. The laryngeal airway nerve monitor of claim 17, wherein the inflation tube is located external to the ventilation tube.

20. The laryngeal airway nerve monitor of claim 1, wherein the dome is configured to dilate a subject's throat.

21. The laryngeal airway nerve monitor of claim 1 , wherein the distal end of the sheath extends beyond the dome.

22. The laryngeal airway nerve monitor of claim 21 , wherein the distal end of the sheath extends between about 0 cm and about 5 cm beyond the dome.

23. The laryngeal airway nerve monitor of claim 1, wherein the sheath has an internal diameter less than about 2 mm.

24. The laryngeal airway nerve monitor of claim 1, wherein the sheath has an internal diameter between about 2 mm and about 10 mm.

25. The laryngeal airway nerve monitor of claim 1, wherein the sheath has an internal diameter greater than about 10 mm.

26. The laryngeal airway nerve monitor of claim 1, wherein the distal end of the sheath is configured to provide a view of a subject's vocal cords when the laryngeal airway nerve monitor is placed in the larynx of the subject.

27. The laryngeal airway nerve monitor of claim 1, wherein the distal end of the ventilation tube extends between about 0 cm and about 5 cm beyond the dome.

28. The laryngeal airway nerve monitor of claim 1 further comprising: a lens coupled to the distal opening of the sheath.

29. The laryngeal airway nerve monitor of claim 1 further comprising: a prism coupled to the distal opening of the sheath.

30. The laryngeal airway nerve monitor of claim 1 further comprising: a cap coupled to the proximal opening of the sheath.

31. The laryngeal airway nerve monitor of claim 1 wherein the cap is tethered to the sheath.

32. The laryngeal airway nerve monitor of claim 1 further comprising: a flap coupled to the proximal opening of the sheath.

33. The laryngeal airway nerve monitor of claim 1 further comprising: a flap coupled to the distal opening of the sheath.

34. The laryngeal airway nerve monitor of claim 1 further comprising: an endoscope received within the sheath, the endoscope having a proximal and distal end.

35. The laryngeal airway nerve monitor of claim 34 wherein the endoscope comprises: a light source.

36. The laryngeal airway nerve monitor of claim 34 wherein the endoscope comprises: a camera located at the distal end of the endoscope.

37. The laryngeal airway nerve monitor of claim 34 wherein the endoscope comprises: an ocular located at the proximal end of the endoscope.

38. The laryngeal airway nerve monitor of claim 34 wherein the endoscope comprises: a first fiber optic cable for the transmission of light from the proximal end of the endoscope to the distal end of the endoscope.

39. The laryngeal airway nerve monitor of claim 34 wherein the endoscope comprises: a second fiber optic cable for the transmission of images from the distal end of the endoscope to the proximal end of the endoscope.

40. The laryngeal airway nerve monitor of claim 34 wherein the endoscope comprises: a channel for the transportation of fluids.

41. The laryngeal airway nerve monitor of claim 34 wherein the endoscope is rigid.

42. The laryngeal airway nerve monitor of claim 34 wherein the endoscope is semirigid.

43. The laryngeal airway nerve monitor of claim 34 wherein the endoscope is flexible.

44. The laryngeal airway nerve monitor of claim 34 wherein the endoscope is steerable.

45. A method of protecting a subject's recurrent laryngeal nerve during surgery, the method comprising: introducing a laryngeal airway nerve monitor into the subject's larynx, the laryngeal airway nerve monitor comprising: a dome; a ventilation tube having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome; and a sheath having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome, and wherein the sheath is configured to receive an endoscope; introducing an endoscope into the sheath; visualizing the subject's vocal cords with the endoscope; identifying a recurrent laryngeal nerve candidate; stimulating the recurrent laryngeal nerve candidate; observing a movement in the subject's vocal cords with the endoscope; and identifying the recurrent laryngeal nerve candidate as the subject's recurrent laryngeal nerve.

46. The method of claim 45, wherein the step of stimulating the recurrent laryngeal nerve candidate comprises applying electrical current to the recurrent laryngeal nerve candidate.

47. The method of claim 45 further comprising: inserting an endotracheal tube through the dome to ventilate the subject.

48. The method of claim 45, wherein the laryngeal airway nerve monitor includes one or more inflatable cuffs and the method further comprises: inflating at least one of the one or more inflatable cuffs.

49. A laryngeal airway nerve monitor comprising: a laryngeal mask airway having: a dome; and a ventilation tube having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome; and a sheath having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome, and wherein the sheath is configured to receive an endoscope.

50. A surgical kit comprising: a laryngeal airway nerve monitor comprising: a dome; a ventilation tube having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome; and a sheath having a proximal and a distal end, each end having an opening, wherein the distal end is in communication with the dome, and wherein the sheath is configured to receive an endoscope; and instructions for use.

51. The surgical kit of claim 50 further comprising: an endoscope configured for passage through the sheath.

52. The surgical kit of claim 50 further comprising: an endotracheal tube adapted for passage through the dome.

53. The surgical kit of claim 50, wherein the instructions for use include instructions for performing the method of claim 45.