GB2397229A

GB2397229A - Apparatus for controlling fluid flow in a Y-shaped channel

Info

Publication number: GB2397229A
Application number: GB0300854A
Authority: GB
Inventors: Susan Ghosh
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-01-15
Filing date: 2003-01-15
Publication date: 2004-07-21
Anticipated expiration: 2023-01-15
Also published as: GB2397229B; GB0300854D0

Abstract

An apparatus for locating into a forked channel having a main channel 19 with first and second forks stemming from said main channel, e.g a forked tracheal channel, the apparatus comprising a main tube section 2 for introduction into the main channel 19 with the said main tube section having first and second lumens 4, 6. The main tube also has sealing means 12, such as an inflatable balloon, located in the distal end region and also seating means 18a, 18b, that abut against the vertex 20, e.g. carina, where the channel bifurcates. The seating means comprise two wings or arms 18a, 18b that rest on each side of the vertex 20, with first and second wings comprising the distal ends of first and second lumens 4, 6 respectively, so that in use each lumen is in independent fluid communication with either of first or second forks. The balloon 12 is inflated via a lumen 16 [Fig. 4] embedded within the wall 8. of the tube 2.

Description

1 2397229 C435.00/G Title: Improvements in or Relating to Fluid Flow

Control Apparatus

Field of the Invention

This invention relates to apparatus and a method for controlling the flow of a fluid within a forked fluid flow channel. More especially the invention particularly relates to an endotracheal ("ET") tube.

Background of the Invention

An endotracheal (ET) tube is an artificial airway device used for medical/surgical reasons to provide a conduit for inspiratory and expiratory gas flow to and from the lungs. ET tubes are used, for example, in the provision of artificial respiratory support and in the delivery of anaesthetic gases to the lungs. They further protect the lungs from soiling by gastric juices spilling over from the pharynx into the trachea in patients whose consciousness is impaired. A number of different types of ET tube are known.

A single lumen endotracheal tube generally consists of a flexible, gently curved plastic or rubber tube. The proximal end can be connected to breathing circuits associated with anaesthetic delivery equipment or to a mechanical ventilator for artificial respiratory support. The distal end, on passage of the tube through the laryngeal aperture, is seated to a depth within the trachea such that it is situated a few centimetres above the carina, (the carina being the anatomical term for the point at which the trachea bifurcates into the left and right main bronchi, that is the main airway passages to the right and left lungs).

Endotracheal tubes may incorporate an inflatable cylindrical or spheroidal cuff bonded to the outer wall of the tube shaft 2 to 3cm from the distal ti?. The cuff is in communication with a pilot balloon, incorporating a spring loaded valve, via a narrow cuM inflation tube, usually moulded into the wall of the endotracheal tube. Inflation of the cuff by application of a cuff inflating syringe to the pilot balloon provides a gas tight seal between the walls of the cuff and the surrounding lining of the treachea. The distal tip of the tube is below the cuff and thus on inflation of the cuff provides a sealed artificial conduit for the passage of gases to and from the lungs.

Separation of the gas flow to the two lungs, or isolation of one lung whilst maintaining gas flow to the other, is required for a variety of medical and surgical reasons. Hitherto this has been achieved in one of three ways: (1) Use of a double lumen endotracheal tube i.e. a tube as described above except with two distinct lumens. One lumen extends beyond the other in the form of a curved extension which is placed within one of the main bronchi. The shorter lumen remains with its opening in the trachea. Separation of gas flow to the lungs is achieved by inflation of two separate cuffs. The first lies above the shorter lumen and provides a seal within the trachea, the second encases the extended limb incorporating the lumen to be placed within a main bronchus. Inflation of this second cuff on the endobronchial limb seals this bronchus off from that on the opposite side, thus effectively separating gas flow between the two lungs, the shorter lumen within the treachea providing gas flow to the bronchus into which the endobronchial limb has not been passed.

(2) Use of a cuffed single lumen tube into one of the main bronchi; inflation of the cuff seals that bronchus off from the opposite side.

(3) Use of a 'bronchus blocker' i.e. an inflatable rubber or plastic balloon on a stalk through the lumen of an endotracheal tube into one of the bronchi. ImPation of the balloon of the bronchus blocker occludes gas flow to that bronchus.

A variety of design of double and single lumen tubes are available for lung solation, but all rely on the passage of a cuffed limb into one of the main bronchi. All existing ET tubes are of a design such that considerable technical expertise is required for correct placement. If the tube is not correctly positioned, gas flow within the patient will not be correctly controllable. The present invention has, as a particular objective of preferred embodiments, the provision of an ET tube which is of a design which facilitates correct placement.

Summary of the Invention

In a first aspect the invention provides apparatus for controlling the flow of a fluid within a forked fluid flow channel, said channel having a main channel, and first and second forks stemming from the main channel at a fork region; the apparatus comprising a tube introducible into the main channel, the tube having first and second lumens defined within the tube within which lumens a fluid may flow, the first lumen being locatable in fluid flow communication with the first fork, the second lumen being locatable in fluid flow communication with the second fork, the tube further comprising sealing means for forming a fluid-tight seal within the main channel and seating means for seating the tube in a desired location within the fluid flow channel, the seating means comprising a bifurcated portion which engages with the fork region, a first arm of the bifurcated portion comprising a distal end of the first lumen and projecting into the first fork and a second arm comprising a distal end of the second lumen and projecting into the second fork; such that, in use, flow of fluid into the first and second forks may be independently ontrolled.

The forked fluid flow channel may be any generally enclosed fluid flow system, such as a forked pipeline for gas, oil, water or the like. More especially however, the forked fluid flow channel constitutes the trachea and main bronchi of a human or animal subject.

In a preferred embodiment the apparatus of the invention is in the form of a double lumen endotracheal tube, for use in a mammalian (typically a human) subject. In such an embodiment the "main channel" into which the tube is introduced is the subject's trachea; the first and second forks are the left and right main bronchi; and the fluid flow being controlled is typically a respiratory gas mixture comprising oxygen.

In a preferred embodiment the apparatus of the invention takes the form of a double lumen ET tube arranged such that each of the two lumens is positionable with its opening opposed to a respective one of the main bronchi, substantially avoiding any requirement for the insertion of a tube or cuff into either bronchus (as generally required by prior art arrnagements).

In a preferred embodiment, the sealing means comprises an expandable cuff, which may be altered in size by varying the amount of a fluid present therein. Conveniently the cuff is inflatable and may be altered in size by varying the amount of a gas (typically air) present therein. The cuff typically takes the form of a generally annular or cylindrical sleeve around the lower, distal end region of the tube. Inflation of the cuff causes it to expand and form a gas-tight seal with the mucosal surface of the adjacent trachea. This ensures that the only gas entering the subject's lungs is that supplied through the lumens of the apparatus. The preferred design of the cuff is such that it substantially encases the distal end region of the tube but does not close off the openings at the ends of the lumens.

In order to facilitate inflation and deflation (or expansion/contraction) of the cuff, it is advantageous that the apparatus comprises cuff expansion/contraction means (more especially, cuff inflation/deflation means). Desirably the cuff inflation/deflation means comprises a relatively narrow bore cuff inflation tube (that is, narrow bore relative to the lumens of the ET tube) which allows for the introduction of air, or other gas, into the cuff.

In one embodiment the cuff inflation tube is moulded, glued, joined or otherwise incorporated into or on the wall of the ET tube.

Typically the apparatus further comprises a pilot balloon at the upper, proximal end region of the cuff inflation tube. A syringe or other device may be attached to the pilot balloon to introduce air or other gas into the cuff, via the cuff inflation tube. To deflate the cuff, a valve (typically a spring-loaded or other biased valve means), conveniently located on the pilot balloon, may be opened to vent the air or other gas from the cuff.

In those embodiments of the invention in which the apparatus is in the form of an ET tube, the seating means is shaped and dimensioned to locate the distal end of the tube at the region where the trachea forks into left and right main bronchi. This region is known as the carina. Conveniently, the bifurcated portion of the apparatus straddles the carina, with one arm projecting towards the left bronchus and the other arm projecting towards the right bronchus, such that one of the lumens of the tube is in fluid flow communication with one lung, and the other lumen is in fluid flow communication with the other lung.

A convenient and preferred arrangement of the two lumens is a "side-byside" disposition, the lumens being separated by a longitudinal partition typically running along or near the centre line of the tube. At the proximal end, the two lumens of the tube may be independently connected to respiratory circuits and provided with fluid flow regulating means, such as valves, taps and the like to regulate, independently if desired, the flow of air or other gas into the left and right lungs of the subject.

Appropriate dimensions and materials for use in the construction of the apparatus of the invention will be apparent to those skilled in the art familiar with conventional ET tubes.

The apparatus of the invention, in its preferred embodiment as an ET tube, has a number of advantages over conventional ET tubes. The bifurcated shape of the distal end of the tube greatly facilitates correct placement: an anaesthetist or other health professional can simply advance the tube within the subject's trachea until resistance to further advancement, provided by the carina, is experienced. The arms of the bifurcated portion prevent rotational movement of the tube within the subject once the arms have passed the tip of the carina. Using this apparatus the lungs can be independently ventilated or isolated substantially without requiring the passage of a tube or sealing cuff into either bronchus.

The invention will now be further described by way of illustrative embodiment and with reference to the accompanying drawings, in which: Figure 1 is a partially schematic front elevation of an endotracheal tube in accordance with the invention; Figure 2 is a partially schematic side elevation of the ET tube illustrated in Figure 1; Figure 3 is a partially schematic end elevation of the distal end of the tube illustrated in the previous Figures; Figure 4 is a partially schematic sectional view across the tube approximately mid-way along its length; and Figure 5 is a partially schematic view of the tube shown in the previous Figures in use in place in the respiratory tract of a human subject.

Detailed Description of an Embodiment of the Invention In one embodiment apparatus in accordance with the invention takes the form of an endotracheal tube as illustrated in Figures 1-S.

The tube, indicated generally by reference numeral 2 in the Figures, is introducible into a main channel, in this instance, a human subject's trachea. The tube 2 is generally cylindrical and formed largely of synthetic plastics material or rubber. The tube 2 comprises a first lumen 4 and a second lumen 6, the lumens 4,6 being essentially semi- ' circular in cross section and disposed in a side-by-side arrangement. The lumens 4, 6 are I defined in part by the outer wall 8 of the tube 2 and in part by a central partition 10.

The distal end region of the tube 2 comprises a sealing means, in the form generally cylindrical inflatable cuff 12. The cuff 12 is in gaseous communication with a pilot balloon 14 provided near the proximal end of the tube 2. A cuff inflation tube 16 is formed within the wall 8 of the tube 2, to allow for air or other gas to be passed into the cuff 12 for inflation, and for gas flow in the opposite direction to allow for deflation of the cuff.

At the distal end of the tube 2 there is also provided a seating means, in the form of a bifurcated portion. The bifurcated portion comprises two short arms 18a, b.

The device is shown in use in Figure 5. The tube 2 is introduced into the trachea l9 in the usual maimer and advanced until further advance is resisted by the subject's carina 20.

The two short arms 18a, b of the bifurcated portion at the distal end of the tube 2 straddle the carina 20 and project a short distance into the left and right main bronchi 22a, b respectively. The cuff 12 is then inflated to form a gas tight seal with the inner surface of the adjacent portion of the trachea 19. This has the effect of isolating the left and right main bronchi, so that gas flow into the bronchi, via lumens 4 and 6 respectively of the tube 2, can be controlled independently. Thus, for example, air supply to one lung can be cut off to allow the lung to be collapsed (e.g. to facilitate surgery on one side of the thorax) i whilst air or other gas supply to the other lung is maintained. In Figure 5 the pilot balloon is omitted for simplicity.

Further embodiments of the invention and minor variations from the features described above will be apparent to those skilled in the art, without departing from the scope of the invention.

Claims

Claims 1. Apparatus for controlling the flow of a fluid within a forked

fluid flow channel, said channel having a main channel, and first and second forks stemming from the main channel at a fork region; the apparatus comprising a tube introducible into the main channel, the tube having first and second lumens defined within the tube within which lumens a fluid may flow, the first lumen being locatable in fluid flow communication with the first fork, the second lumen being locatable in fluid flow communication with the second fork, the tube further comprising sealing means for forming a fluid- i tight seal within the main channel and seating means for seating the tube in a desired location within the fluid flow channel, the seating means comprising a bifurcated portion comprising a distal end of the first lumen and projecting into the first fork and a second arm comprising a distal end of the second lumen and projecting into the second fork; such that, in use, flow of fluid into the first and second forks may be independently controlled.
2. Apparatus according to claim 1, in the form of an endotracheal tube for introduction into the respiratory tract of a human or animal subject.
3. Apparatus according to claim 1 or 2, wherein the sealing means comprises an expandable cuff which may be altered in size by varying the amount of a fluid present therein.
4. Apparatus according to claim 3, wherein the expandable cuff is inflatable.
5. Apparatus according to claim 3 or 4, wherein the cuff substantially encases a distal end region of the tube but does not close off the openings at the ends of the lumens.
6. Apparatus according to any one of claims 3, 4 or 5, comprising a relatively narrow bore cuff inflation tube moulded, glued, joined or otherwise incorporated into or on the wall of the tube.
7. Apparatus according to any one of the preceding claims, wherein the seating means is shaped and dimensioned to locate the distal end of the tube in a subject at the region where the trachea forks into left and right bronchi.
8. Apparatus according to claim 7, wherein the bifurcated portion straddles the carina of a subject into which the apparatus is introduced such that one of the lumens of the tube is in fluid flow communication with one lung and the other lumen is in fluid flow communication with the other lung.
9. A method of controlling the flow of a respiratory and/or anaesthetic gas to a human or animal subject, comprising introducing into the trachea of the subject apparatus in accordance with any one of claims 1-8.
10. A method according to claim 9, wherein the lungs of the subject may be independently ventilated or isolated substantially without requiring the passage of a tube or sealing cuff into either bronchus.

Apparatus substantially as hereinbefore described and with reference to the accompanying drawings.