GB2549063A

GB2549063A - A Recurrent Laryngeal Nerve (RLN) sensing system

Info

Publication number: GB2549063A
Application number: GB1600633.0A
Authority: GB
Inventors: Hovey Chris
Original assignee: Magstim Co Ltd
Current assignee: Magstim Co Ltd
Priority date: 2016-01-13
Filing date: 2016-01-13
Publication date: 2017-10-11
Also published as: GB201600633D0

Abstract

A sensor system 2 for sensing activity in a target recurrent laryngeal nerve (RLN) comprises an elongate endotracheal tube 10 for insertion through a nasal passageway. The tube has a maximum transverse dimension of 5 mm. A maximum internal transverse dimension may be 3 mm. A sensor arrangement 6 is disposed on an external surface of the tube. The sensor arrangement comprises sensors 18 extending longitudinally along the tube for sensing electrical activity in the RLN. Each of the sensors 18 is at least partially unsecured relative to the tube to enable lateral sensor movement. This allows the sensors to conform to the anatomical geometry of the trachea. The tube may comprise a portion, e.g. a bend 14 in the tube, to limit insertion into the nose. The sensors may be secured to the tube at a spaced apart first zone 20 and second zone 22.

Description

A Recurrent Laryngeal Nerve (RLN) Sensing System

The present invention relates to a sensing system for sensing activity in a nerve or muscle. A significant risk when performing surgery in the area around the oropharynx, larynx, trachea or oesophagus is possibility of damaging the recurrent laryngeal nerves (RLNs). These nerves are extremely delicate and even identification through touch can cause significant damage leading to potential full or partial vocal cord paralysis. A known procedure during surgery where there is a possibility of causing damage to the RLNs is to position an endotracheal tube carrying a sensing arrangement having one or more electrodes thereon in the general area of the vocal cords. During the surgical procedure, a surgeon places a probe in the area external of the patient around where he or she believes the nerves to be located. The nerves contract upon application of a voltage from the probe, causing the generation of their own electrical pulse which may be sensed by the sensing arrangement. An output is then taken from the electrodes to be presented to the surgeon in order that the surgeon is informed whether the probe is close to the nerves and thus to minimise trauma in that area. A problem exists in that in certain circumstances where either access to the pharynx during surgery is required for cancer treatment or where oral intubation is difficult.

According to the present invention there is a sensor system for sensing activity in a target recurrent laryngeal nerve (RLN), the sensor system comprising: an elongate endotracheal tube for insertion through a nasal passageway having a longitudinal length and a maximum transverse dimension of 5mm; a sensor arrangement disposed on an external surface of the elongate endotracheal tube, the sensor arrangement comprising a plurality of longitudinally extending sensors for sensing electrical activity in the RLN, wherein at least a part of each of the plurality of sensors is unsecured relative to the endotracheal tube to enable movement of the sensors laterally to enable conformity of the sensors to the anatomical geometry of the trachea.

The applicant has determined that the provision of a tube having a diameter of less than 5mm and also a sensor arrangement having sensors as defined means that insertion through a nasal passageway is possible. This is enables by the small diameter tube, and also the ability of the sensors to deform meaning that the overall diameter during insertion is minimised. Once positioned the sensors can then move outwardly relative to the tube to conform to the geometry of the trachea. Such sensors are capable of deforming to become pressed against the tube having minimal impact upon the effective increase in maximum external transverse dimension of the sensor system.

The endotracheal tube preferably comprises an insertion limiting portion arranged to limit insertion of the endotracheal tube into the nasal cavity. The endotracheal tube is beneficially deformed to form an insertion limiting portion. The insertion limiting portion may comprise a bend portion of the endotracheal tube. This is beneficial as during intubation the tube cannot be inserted too far leading to potential damage to the lungs. The endotracheal tube beneficially comprises a distal end comprising a tip that is inserted first into the nasal cavity. The proximal end remains out of the patient in use. The insertion limiting portion is provided at the proximal end.

The maximum transverse dimension is preferably between 4mm and 5mm, and is preferably less than 5mm.

The maximum internal transverse dimension of the endotracheal tube is preferably 3mm. Preferably, the maximum internal transverse dimension of the endotracheal tube is between 2mm and 3mm. The endotracheal tube is preferably circular in cross section both internally and externally.

The sensor system preferably further comprises an output element in communication with the sensors for providing an output indicative of the measured activity of the RLN. The output element may be in the form of a flexible element extending from the sensor arrangement along the longitudinal length of the tube. The flexible element may be wrapped around the tube.

The plurality of sensors are preferably secured relative to the endotracheal tube at a spaced apart first zone and second zone. This means that intermediate the first zone and second zone the sensors can billow outwardly and conform to the geometry of the trachea. It further means that the sensors can readily deform to become adjacent to the tube during insertion.

The sensors preferably comprise a body arranged to carry an electrode. The electrode is beneficially printed onto the sensor body. The sensor arrangement preferably comprises a multi-sensor array. The multi-sensor array is preferably a single sheet sensor.

The invention will now be described by way of example only with reference to the accompanying drawing in which:

Figure 1 is a schematic perspective view of a sensor system according to an exemplary embodiment of the present invention.

Referring to Figure 1, there is a sensor system 2 formed of an endotracheal tube 4 and a sensor arrangement 6. The tube 4 comprises an elongate tube defining a conduit therethrough, wherein the outer diameter of the tube is between 4-5mm. Such an outer diameter means the tube can be inserted into a nasal passageway rather than through a patient’s mouth which is beneficial particularly in the case where oral intubation is difficult or access is required to the pharynx during surgery.

The tube 4 comprises a proximal and distal end 8,10 wherein the proximal end 8 comprises an insertion limiting formation 12. The insertion limiting formation 12 prevents the tube from being inserted too far into the patient and causing possible damage to the lungs. The insertion limiting formation may be a bent portion, or kink in the tube 4. Upon insertion once the ‘U’shape 14 of the tube 4 contacts the nose, then the user is aware that the sensor arrangement 6 is in the appropriate location within the patient.

The sensor arrangement 6 is adhered to the tube 4, which may be carried out by the medical practitioner depending on a calculated trachea length of the patient. Markings may be provided on the tube 4 to aid in relative positioning. The sensor arrangement 6 comprises a body 16 and a plurality of sensors 18 in the form of longitudinally extending strips. On the strips are printed electrodes which in operation contact the RLNs. These electrodes may be printed using conductive ink. At spaced apart longitudinal positions are first and second spaced apart zones 20, 22 where the strips 18 are fixed to the body 16 which in turn is fixed to the tube 4. Intermediate the first and second zones 20, 22 the strips are free to move laterally relative to the tube 4 and thus billow outwardly in order that they may conform to the anatomical geometry of the RLNs and surrounding tissue to prevent damage to the tissue in this area.

The sensor arrangement 6 further comprising an output element 24 extending from the sensor body for transferring an electrical signal to monitoring equipment located outside the patient’s body. In the embodiment presented this is achieved via an elongate cable wound around the tube 4. A connector is provided at a distal end 26 of the output element 24 for engagement with monitoring equipment.

The present invention provides a sensor system that can be utilised for nasal entry for RLN monitoring. The combination of the tube 4 external dimensions and the sensing strips 18 allows entry through the limited opening of the nasal passageway whilst further allowing access to the mouth. The sensors effectively squash to be directly adjacent the tube during insertion meaning that the overall external diameter is not significantly increased, but once in position the sensors can then billow outwardly to an operative configuration.

The present invention has been described by way of example only and it will be appreciated to the skilled addressee that modifications and variations may be made without departing from the scope of protection afforded by the appended claims.

Claims

1. A sensor system for sensing activity in a target recurrent laryngeal nerve (RLN), the sensor system comprising: an elongate endotracheal tube for insertion through a nasal passageway having a longitudinal length and a maximum transverse dimension of 5mm; a sensor arrangement disposed on an external surface of the elongate endotracheal tube, the sensor arrangement comprising a plurality of longitudinally extending sensors for sensing electrical activity in the RLN, wherein at least a part of each of the plurality of sensors is unsecured relative to the endotracheal tube to enable movement of the sensors laterally to enable conformity of the sensors to the anatomical geometry of the trachea.

2. A sensor system according to claim 1 wherein the endotracheal tube comprises an insertion limiting portion arranged to limit insertion of the endotracheal tube into the nasal cavity.

3. A sensor system according to claim 2 wherein the endotracheal tube is deformed to form an insertion limiting portion.

4. A sensor system according to any of claims 2-3 wherein the insertion limiting portion comprises a bend portion of the endotracheal tube.

5. A sensor system according to any preceding claim wherein the maximum transverse dimension is between 4mm and 5mm, and is preferably less than 5mm.

6. A sensor system according to any preceding claim wherein the maximum internal transverse dimension of the endotracheal tube is 3mm.

7. A sensor system according to any preceding claim comprising an output element in communication with the sensors for providing an output indicative of the measured activity of the RLN.

8. A sensor system according to any preceding claim wherein the plurality of sensors are secured relative to the endotracheal tube at a spaced apart first zone and second zone.

9. A sensor system as hereinbefore described with reference to the accompanying drawings.