GB2515163A

GB2515163A - Device for removal of gas from a respiratory circuit

Info

Publication number: GB2515163A
Application number: GB1406648.4A
Authority: GB
Inventors: Andreas Brandt; Ralf Heesch; Gerd Peter; Mike Dahncke
Original assignee: Draeger Medical GmbH
Current assignee: Draeger Medical GmbH
Priority date: 2011-11-12
Filing date: 2012-11-12
Publication date: 2014-12-17
Also published as: GB201406648D0; CN103930025A; WO2013068580A1; EP2775913A1

Abstract

A device (1) for removal of gas from a respiratory circuit comprises a first subsection (2) for connection to an inhalation branch of a respirator system, a second subsection (3) for connection to an exhalation branch of the respirator system, and a third subsection (4) with a tube connection opening (5) for insertion of a tube adapter (17), wherein the first subsection opens into the third subsection via a first opening (6), and the second subsection opens into the third subsection via a second opening (7). The device further comprises a gas removal tube (8) which stretches from an opening (9) in a wall (10) of the third subsection to a first gas removal tube end (12) that has a removal opening (11) extending into the third subsection, so that when the tube adapter is plugged in, the removal opening is essentially concentric with an opening (18) in the tube adapter, and the first end, relative to a direction (16) in which exhaled respiratory gas primarily exits from the opening in the tube adapter when the device is used, is arranged underneath an edge (13) of the first opening and an edge (14) of the second opening. The first end has an end face (25) that connects an edge (24) of the first end (12) which delimits an outer wall (8a) of the gas removal tube (8), to an inner wall (8b) of the gas removal tube (8) surrounding the removal opening (11). At least 40 percent of the end face (25) is in a funnel shape and has an opening angle (15) between 130Â° and 170Â°.

Description

Device for removing gas from a respiratory circuit The invention relates to a device for removing gas from a respiratory circuit.

Respiration systems are usually used in medical applications for assisting with respiration and/or for administering anaesthetics during surgical procedures.

Whilst in anaesthetic systems the respiratory gas is circulated in a circuit and fed back to the patient, after the carbon dioxide contained in the exhaled air has been removed in a carbon-dioxide absorber, in respiration systems in intensive-care medicine mostly an open circuit is used, that is, the exhaled air is fed to the air in the room.

When patients are intubated, the tube is connected to the respiration system by means of a tube-adapter formed on the tube and inserted into an opening of a connection piece.

Usually, the connection piece is formed in the shape of a Y with legs which are bent off and in which respective openings are provided for the connection of the tube-adapter as well as of the inspiration branch and of the expiration branch of the respiration system. Such a connection piece is termed a Y-piece on account of its shape.

In the Y-piece a gas-removal pipe can be guided through a wall of the Y-piece in order to remove a gas sample from a respiratory gas flowing in The respiration system. Such a gas-removal pipe is used in particular in order to remove a gas sample of the expiratory respiratory gas, that is, of the gas exhaled by a patien, in order, for example, to determine its carbon-dioxide content (EtCO2) A 1-piece having a gas-removal pipe is known, for example, from Us 5,213,096 A. Here, the gas-removal pipe projects through the Y-piece as far as the end of a pipe-socket to which a tube can be connected by way of a patient-connection piece formed in The manner of bellows. The patient-connection piece then constitutes an additional volume which can have a disadvantageous effect in the case of the respiration of neonaes, since the tidal volume of neonates only lies between 5 ml and 10 ml.

A 1-piece directly enabling the insertion of a tube-adapter formed on a tube and thus having a small dead space is known from EP 2 359 889 Al. Here, a gas-removal pipe only projects in part into a connection piece, used for the insertion of the tube-adapter, so that the tube-adapter can be inserted. Formed at the end of the gas-removal pipe pointing towards the tube-adapter there are webs which guarantee that during inserrion the opening in the tube-adapter cannot be covered by the gas-removal pipe or in the extreme case completely sealed thereby.

Mixing of inspiratory and expiratory respiratory gas can result within the Y-piece. In particular in the case of the measurement of the 002-content of the expiratory respiratory gas, coinmixture with oxygen-rich inspiratory respiratory gas should be avoided to the greatest possible extent. A reduction in undesirable mixing of inspiratory and expiratory respiratory gas is achieved in the case of the 1-piece in accordance with EP 2 359 889 Al owing to the fact that the removal of gas occurs directly above the opening in the tube-adapter. A small flow of inspiratory respiratory gas that is maintained during the expiration phase therefore primarily flows above the gas-removal pipe so that more precise determination of the EtCO2-value is rendered possible.

The underlying object of the invention is to specify an advantageous device for removing gas from a respiratory circuit in which any mixing cf inspiratory and expiratory respiratory gas is further reduced.

This object is achieved with the device in accordance with claim 1.

Advantageous configurations and further developments of the invention constitute subjeci matter of the dependent claims.

The device in accordance wiTh the invention for removing gas from a respiratory circuit comprises a first subsection for connection to an inspiration branch of a respiration system, a second subsection for connection to an expiration branch of the respiration system, and a third subsection with a tube-connection opening for insertion of a tube-adapter, wherein the first subsection, by way of a first opening, and the second subsection, by way of a second opening, open into the third subsection. The device in accordance with the invention further comprises a gas-removal pipe which, starting from a wall opening in a wall of the third subsection, stretches with a first end that has a removal opening into The third subsection so that the removal opening, when the tube-adapter is inserted, is arranged so as to be substantially concentric with an opening that is formed in the tube-adapter, and the first end, relative to a direction in which, when the device is used, expiratory respiratory gas primarily exits from the opening in the tube-adapter, is arranged below an edge of the first opening and an edge of the second opening. In this connection, the first end has an end face which connects an edge of the first end delimiting an outer wall of the gas-removal pipe to an inner wall of the gas-removal pipe surrounding the removai opening. In accordance with the invention, at least 40 percent of the end face is formed in the shape of a funnel and with an opening angle between 130° and 170°.

The effect of the funnel-shaped region of the end face of the first end is that, when the tube-adapter is connected, expiratory respiratory gas flowing out of an opening in the tube-adapter and flowing against the funnel-shaped region of the end face is directed back at least in part in the direction of the tube and is thereby swirled. These swirls develop within the third subsection in a region below the openings of the first subsection and the second subsection and in this way form, in particular in a region lying between the opening in the cube-adapter and the removal opening, a barrier for inspiratory respiratory gas which flows from the first subseccion to the second subsection during an expiration phase of a respiration cycle. Any mixing of the inspiratory respiratory gas with expiratory respiratory gas exhaled by a patient is reduced by the swirls of the expiratory respiratory gas, in particular in the region of the removal opening. In the ideal case, as a result, unmixed expiratory respiratory gas from the opening in the tube-adapter reaches the removal opening.

The device in accordance wich the invention thus makes it possible to operate a respiration system in such a way that during the expiration phase inspiratory respiratory gas can also flow by way of the inspiration branch through the Y-piece into the expiration branch, whilst at the same time expiratory respiratory gas can be removed from the Y-piece, and measurement of the C02-concentration in the expiratory respiratory gas can be carried out with a high degree of precision.

A funnel-shaped design of a region of the end face for the purposes of this application is to be understood in such a way that the funnel-shaped region of the end face connects the edge of the first end to the inner wail of the gas-removal pipe surrounding the removal opening, whilst the first end then tapers, in the direction of the removed expiratory respiratory-gas flow, from the diameter at the edge of the first end to the diameter of the removal opening. It is irrelevant in this connection whether the taper is linear or along an arched curve. A construction with a discontinuous course of the taper, for example as a result of a substantially right-angled step, shall also come under the term "funnel-shaped".

What is to be understood by an opening angle is that angle which exists in the case of a section through the centre of the removal opening between the straight lines that result when the two points defining the diameter at the edge of the first end are connected to, in each case, the nearest of the two points on the inner wall of the gas-removal pipe defining the diameter of the removal opening. In the case of a linear taper these straight lines thus lie on the surface.

The gas-removal pipe can be formed in particular as a hollow cylinder. However, a gas-removal pipe with an outer and/or inner cross section formed elliptically, rectangularly or polygonally as well as irregularly over the whole length or partial regions of the gas-removal pipe shall also be included.

A substantially concentric arrangement of the removal opening with the opening formed in the tube-adapter is to be understood to the effect that in each case a deviation from an exactly concentric arrangement on account of manufacturing tolerances and preferably also a structural deviation that does not or only negligibly influences the effect of the swirl-formation shall he included. A deviation on account of manufacturing tolerances preferably includes a deviation of up ro 20% of the diameter of the removal opening and a strucrural deviation a deviation of up to 50% of the diameter of the removal opening.

In a preferred configuration of the invention, the angle-bisector of the opening angle is substantially parallel to the direction in which, when the device is used, expiratory respiratory gas primarily exits from the opening of the connected tube-adapter into the third subsection.

Whilst the gas-removal pipe above the first end can, for example, also extend obliquely to the direction of the expiratory respiratory gas exiting from the tube-adapter, irrespective of the further course of the gas-removal pipe as a result of the advantageous alignment of the funnel-shaped region of the end face of the first end, the effect is a flow of expiratory respiratory gas flowing out of the connected tube-adapter against the funnel-shaped region that is as uniform as possible so that a swirl-formation that is as uniform as possible can be attained.

Advantageously, the ratio of the diameter at the edge of the first end to the diameter of the tube-connection opening lies between 0.35 and 0.65.

Furthermore, it is advantageous if the ratio of the diameter of the removal opening to the diameter at the edge of the first end lies between 0.125 and 0.4.

As a result of the preferred choice of the dimensions of the first end and also of the removal opening, it is possible to achieve a particularly effective swirl-formation. In this case, the choice of the diameter at the edge of the first end and the choice of the diameter of the removal opening, already when considered on their own, have an advantageous effect upon the formation of the swirls. A parameter range that also satisfies the above-mentioned ratio to the diameter of the tube-connection opening is, however, particularly advanrageous.

A further development of the invention provides that formed at the first end of the gas-removal pipe there is at least one web which stretches furcher into the third subsection than the first end so that a tube-adapter can be inserted into the third subsection maximally as far as the web.

In this way, a situation is prevented from occurring where the tube-adapter is pressed against the first end, as a result of which the opening in the tube-adapter could be sealed in the extreme case. As a result of the at least one web it is thus guaranteed that expiratory respiratory gas can always flow radially to the first end in the direction of an inner wall of the third subsection and in particular can form swirls in this region. Different embodiments of such webs at an end of a gas-removal pipe are known to the person skilled in the art from EP 2 359 889 Al. In the case of the embodiment with webs, the webs cover a portion of the end face of the first end that is available without webs for The region formed in a funnel shape. The region of the end face formed in a funnel shape in this case maximally includes the region of the end face that is not covered by webs. If the portion of the end face that is covered by the region formed in a funnel shape is specified in this application, this portion always refers to the end face that is available without webs.

Advantageously, the portion of the gas-removal pipe extending in the device is connected by means of a partition wall to an inner wall of the third subsection that is arranged between the first opening and the second opening in such a way that, when the device is used, inspiratory respiratory gas flowing out of the first opening against a side of the partition wall must flow around the gas-removal pipe and/or through underneath the partition wall in order to be able to reach the other side of the partition wall and from there flow out by way of the second opening.

In this way, a flow of inspiratory respiratory gas that is maintained during the expiration phase and flows from the inspiration branch, connected to the first opening, to the expiration branch, connected to the second opening, obtains a preferred direction around the gas-removal pipe, as a result of which the displacement effect of the swirls is assisted.

Advantageously, the web and the partition wall are formed in one piece.

It is particularly advantageous if the third subsection substantially extends perpendicularly to the one plane spanned by the first subsecrion and the second subsection.

In this way, the direction of flow of the inspiratory respiratory gas out of the first subsection into the third subsection is substantially perpendicular to the direction of flow of the expiratory respiratory gas flowing out of the opening in the tube-adapter into the third subsection.

As a result, the swirls around the gas-removal pipe can be formed more easily, and a lower intensity of the swirls is reguired in order primarily to force the inspiratory respiratory gas flowing in out of the first subsection out of the region lying below the first opening and the second opening. In particular, the displacement of the inspiratory respiratory gas out of the region lying between the opening in the tube-adapter and the removal opening is promoted in this way.

A respiration system having a device in accordance with the invention also constitutes subject matter of the invention.

The invention is explained in greater detail in the following with the aid of exemplary embodiments shown in the figures, in which: Figure 1 shows a device in accordance with the invention in the form of a Y-piece; Figure 2 shows a section along A-A through the device in accordance with Figure 1; and Figure 3 shows a section along B-B through the device in accordance with Figure 1.

Reference numerals that are the same in the figures denote the same objects.

Figure 1 diagrammatically shows a view from below of a device 1 in accordance with the invention for removing gas from a respiratory circuit of a respiration system. For reasons of clarity, the other components of the respiration system are not shown. The other components are known to the person skilled in the art and do not constitute subject matter of the invention. Ar least, the respiration system has a respiration apparatus for adjusting and detecting respiration parameters, or alternatively an anaesthesia apparatus, as well as an inspiration branch leading from the respiration apparatus to the device 1, comprising at least one respiratory hose, and an expiration branch leading from the device to The respiration apparatus, comprising at least one respiratory hose.

The device 1 has a first subsection 2 to which the inspiration branch, which is not shown, of the respiration system is connected. A second subsection 3 is connected to the expiration branch, which is not shown, of the respiration system. The first subsection 2 and the second subsection 3 open into a third subsection 4 which has a tube-connection opening 5 into which a tube-adapter is inserted so that, when the device 1 is used, a tube introduced into the trachea of a patient can be inserted directly into the tube-connection opening 5 by way of a tube-adapter formed on the rube. For reasons of clarity, the tube-adapter is not shown in Figure 1, and representations of the tube as well as of the intubated patient have also been dispensed with.

As can be seen diagrammatically from Figure 2, the first subsection 2 with a first opening 6 and the second subsection 3 with a second opening 7 open into the third subsection 4. In this connection, the third subsection 4 in this exemplary embodimenr extends perpendicularly to a plane spanned by the first subsection 2 and the second subsection 3.

Cf course, both the first subsection 2 and the second subsection 3 can, in each case, have an angle, with respect to an axis running through The third subsection 4, that is greater than or preferably also smaller than 900.

Starting from a wall opening 9 in a wall 10 of the third subsection 4, a gas-removal pipe 8 stretches with a first end 12 that has a removal opening 11 into the third subsection 4 so that the removal opening 11 is arranged substantially concentrically with the tube-connection opening 5, and the first end 12 lies closer to the tube-connection opening 5 than an edge 13 of the first opening 6 and than an edge 14 of the second opening 7. An end face 25 of the first end 12 connects an inner wall 8b of the gas-removal pipe 8 surrounding the removal opening 11 to an edge 24 of the first end 12 delimiting an outer wall Ba of the gas-removal pipe 8. As can be seen from Figure 2, the end face 25 is formed partly in the shape of a funnel, that is, it has a region that is formed in a funnel shape that is interrupted by webs 19, 20 described below. The region of the end face 25 formed in a funnel shape has an opening angle 15 between 130° and 170° and covers more than 40 percent of the end face that is available without webs. In this case, the region of the end face 25 formed in a funnel shape connects the edge 24 of the first end 12 to the inner wall Bb surrounding the removal opening 11, whilst The first end 12 simultaneously tapers in a linear manner in the direction of the expiratory respiratory-gas flow, removed by way of the removal opening 11, from a diameter 26 at the edge 24 of the first end 12 to the diameter of the removal opening 11.

Cf course, in an exemplary embodiment that is not shown, the taper can also be effeced by means of an arched curve opening towards the tube-connection opening or a step likewise opening towards the tube-connection opening.

If now, as diagrammatically shown in Figures 2 and 3, a tube-adapter 17 is inserted into the third subsection 4, the region of the end face 25 formed in a funnel shape roofs over an opening 18 in the tube-adapter 17 in the manner of a shield. Expiracory respiratory air exits from the tube-adapter 17 during an expiration phase, primarily in a direction 16 out of the opening 18 into the third subsection 4. Owing to the fact that the angle-bisector of the opening angle 15 in the exemplary embodiment is parallel to the direction 16, the opening 18 is uniformly roofed over by the region of the end face 25 that is formed in a funnel shape.

Expiratory respiratory gas flowing out of the opening 18 flows, on the one hand, parrly directly into the removal opening 11 and, on the other hand, against the region of the end face 25 formed in a funnel shape so that expiratory respiratory gas flowing against the region of the end face 25 formed in a funnel shape is directed back in part in the direction of the tube-adapter 17, as a result of which swirls 23 develop which, as diagrammatically shown in Figure 2, stretch as far as a region between the edge 13 of the first opening 6 as well as the edge 14 of the second opening 7 and the first end 12, extend along an inner wall of the third subsection 4 in the direction of the tube-adapter 17 and together with the expiratory respiratory gas flowing out of the tube-adapter 17 flow back in the direction of the first end 12 or the funnel-shaped region of the end face 25 again. Inspiratory respiratory gas that is introduced out of the first subsection 2 into the third subsection 4 during operation of the respiration system during the expiration phase reaches the region in which the swirls 23 are formed in a lower concentration than would be the case without swirls. Tn particular, the swirls 23 make it more difficult for inspiratory respiratory gas from the first subsection 2 in the expiration phase to be able to reach the region of the removal opening 11. Instead, expiratory respiratory gas flowing out of the opening 18 in the tube-adapter 17 primarily without intermixing with the oxygen-containing inspiratory respiratory gas from the inspiration branch connected to the first subsection 2 reaches the removal opening 11 and, from there by way of the wall opening 9 and a hose, which is not shown, and beyond, an analyzer, which is likewise not shown, in which, for example, the concentration of the carbon dioxide in the expiratory respiratory gas is determined.

As a result of the special configuration of the first end 12 of the gas-removal pipe 8 with the end face 25, at least 40% of which is formed in a funnel shape with an opening angle between 1300 and 170°, inspiratory respiratory gas flowing into the third subsection 4 from the first subsection 2 in the expiration phase is guided on the swirls 23 as on an air cushion and is primarily directed around the gas-removal pipe 8 and then exits by way of the second opening 7 in the second subsection 3 from the device 1 into the expiration branch connected to the second subsection 3.

In order to impart a preferred direction of flow to an inspiratory respiratory-gas flow from the first subsection 2 to the second subsection 3 and to promote gliding on the swirls 23 as a result, a partition wall 21 is arranged between the gas-removal pipe 8 and an inner wall 22 of the third subsecrion 4 arranged between the first opening 6 and the second opening 7 so that inspiratory respiratory gas cannot flow directly along the inner wall 22 from the firs opening 6 into the second opening 7, but must previously flow around the gas-removal pipe 8 or to a lesser extenc must flow through underneath the partition wall 21 in order to reach the second opening 7.

To manufacture the device 1 in a particularly advantageous manner, the partition wall 21 is formed so as to be in one piece with the inner wall 22 and the gas-removal pipe 8.

Cf course, it is also possible to glue or latch the partition wall 21 in place or fit it in with other securing means, with which the person skilled in the art is familiar, between the gas-removal pipe 8 and the inner wall 22.

The web 19 and the web 20 follow on from the first end 12 of the gas-removal pipe 8. The webs 19, 20 have, on the side facing the tube-adapter 17, an area which is substantially perpendicular to an axis extending through the removal opening 11. The webs 19, 20 then subdivide the end face 25 of the first end 12 into two subregions, which together form the region of the end face 25 ifformed in a funnel shape, and two flat regions ifformed by the webs 19, 20. The webs 19, 20 then project further into the third subsection 4 than the first end 12, the effect of which as a result is that the tube-adapter 17 can be pushed in maximally so far until it rests against the web 19 and the web 20.

Expiratory respiratory gas flowing out of the opening 18 can thus, even when there is a tube-adapter 17 resting against the webs 19, 20, flow against the region o the end face 25 that is formed in a funnel shape and from there be laterally deflected so that the swirls 23 that were described previously are formed.

Cf course, just one web or more than two webs can also be provided. Preferably, however, two webs 19 and 20 are used, since on the one hand as a result it is guaranteed that when the tube-adapter 17 is pushed in too far it rests against two surfaces and thus sits in the third subsection in a non-tilted state. With just one web, tilting could result if the tube-adapter 17 has clearance in the third subsection 4. On the other hand, with a limitation to two webs it is possible at the same time to form a coherent region of the end face of the first end 12 in a funnel shape that is as large as possible.

It is particularly favourable if the web 19, as shown in the exemplary embodiment, is connected in one piece to the partition wall 21 and to the first end 12. Of course, the web 19 can, in the same way as the web 20, also be secured to the partition wall 21 and/or to the end face of the first end 12 of the gas-removal pipe 8 by means of securement that are known to the person skilled in the art, such as, for example, gluing.

In the exemplary embodiment shown in the Figures, the angle-bisector of the opening angle is parallel to the direction 16 in which expiratory respiratory gas exits from the opening 18 of the tube-adapter 17. Of course, swirl-formation is already achieved if the angle-bisector of the opening angle 15 is substancially parallel to the direction 16. What is to be understood by substantially in this context is that a deviation from the parallel lies in the order of magnitude of usual manufacturing tolerances, that is, in the range of up to 1°. Of course, swirls are also still formed if the angle-bisector of the opening angle 15 does not lie substantially parallel to the direction 16, but has deviaions of more than 1°. In this context, it holds good that the formation of the swirls 23 occurs in a more effective manner, the closer the angle lies to 0°.

In the exemplary embodiment, the gas-removal pipe 8 is substantially arranged so as to be concentric with the tube-connection opening 5 of the third subsection 4. Of course, the gas-removal pipe 8 can also be introduced obliguely into the third subsection 4. It is merely necessary for the removal opening 11 to be arranged so that it is substantially concentric with the tube-connection opening 5 so that the region of the end face 25 formed in a funnel shape can roof over The opening 18, which is usually arranged centrically in the tube-adapter 17, uniformly and in the manner of a shield.

The device 1 in accordance with the invention can be used both in a respiration system in intensive-care medicine and in an anaesthetic system. Use of the device 1 in accordance with the invention in a respiration system used for the respiration of a neonate is particularly advantageous. As a result of the direct insertion of the tube-adapter 17 into the device 1, the dead volume between the tube and the device 1 is kept as small as possible, whilst at the same time, as a result of the configuration in accordance with the invention of the first end 12 of the gas-removal pipe 8, precise measurement of the C02-content in the expiratory respiratory gas is possible even if a flow of inspiratory respirarory gas is conducted through the device 1 during the expiration phase.

IJTST OF REFERENCE NUMERRIJS

1 Device fcr removing gas 2 First subsection 3 Second subsection 4 Third subsection Tube-connection opening 6 First opening 7 Second opening B Gas-removal pipe 8a Outer wall of the gas-removal pipe 8b Inner wall of the gas-removal pipe 9 Wall opening Wall 11 Removal opening 12 First end of the gas-removal pipe 13 Edge of the first opening 14 Edge of the second opening Opening angle outside diameter 16 Direction in which gas primarily exits from a tube 17 Tube-adapter 18 Opening in the tube-adapter 19 Web Web 21 Partition wall 22 Inner wall 23 Swirls 24 Edge of the first end End face of the first end 26 Diameter at the edge of the first end