Heat and moisture exchange devices, elements and assemblies

Abstract

HME device 2 for a tracheal tube 1 has an outer housing 21. Outer housing 21 has an HME element 20 at its patient end spaced from the housing by an annular recess 40. HME element 20 is retained in outer housing 21 by clip fittings 29 and 30. An inner surface 26 of housing 21 is tapered to fit over the outside of connector 13 on tube 1 such that the connector extends into recess 40. HME element 20 can be removed from tube 1 by extending into connector 13 and releasing the clip fitting with outer housing 21.

Description

[Technical field]

[0001] The present invention relates to an HME device of the type that includes an outer housing and at least one HME element attached to the housing, the HME device being arranged to mate with a cooperating connector on a respiratory device. [Background technology]

[0002] When a patient breathes through a tube inserted into the trachea, such as a tracheotomy tube or an endotracheal tube, the gas flow to the bronchi is not warmed and humidified by the passages through the nose. Unless the gas is warmed and humidified in some way, it may cause damage and discomfort to the patient's throat. The gas can be conditioned by a humidifier in the ventilation circuit. However, it is most convenient to use a heat and moisture exchange device (HME). HMEs are small, lightweight devices that contain one or more HME exchange elements. When the patient exhales, the gas passes through the exchange element and gives up most of its heat and moisture to the exchange element. When the patient inhales, the gas passes in the opposite direction through the exchange element and takes up most of the heat and moisture in the exchange element. Thus, the gas inhaled by the patient is warmed and humidified. These HMEs are low cost and can be disposed of after a single use. These HMEs can be connected to a breathing circuit or simply connected to the machine end of the tracheal tube and left open to atmosphere if the patient is spontaneously breathing. HMEs can be used in conjunction with other breathing devices such as face masks.

[0003] HMEs are sold by Smiths Medical International Ltd., Ashford, Kent, UK under the trade name Thermovent (Thermovent is a registered trademark of Smiths Medical International Ltd), by Hudson RCI AB under the trade name Trach Vent (Trach Vent is a registered trademark of Hudson RCI AB), by DAR, Medisize, Intersurgical and other manufacturers. Examples of HMEs are disclosed in patent documents 1 to 23 (GB 2391816, WO 01 / 72365, U.S. Pat. No. 5,505,768, SWE 516666, U.S. Pat. No. 3,881,482, DE 20302580, DE 20114355, WO 97 / 01366, U.S. Pat. Appl. Pub. No. 2002 / 0157667, U.S. Pat. No. 6,422,235, EP 1,208,866, No. 4,971,054, EP No. 1,699,515, U.S. Patent No. 5,035,236, EP No. 535,016, U.S. Patent No. 5,647,344, GB Patent No. 2,267,840, EP No. 856,327, EP No. 1,699,515, U.S. Patent No. 7,363,925, WO 15 / 107320, U.S. Patent Application Publication No. 2008 / 0099013 and GB Patent No. 2,540,456).

[0004] A conventional HME has a female connection port that fits over a typical male 15mm connector at the machine end of a tracheostomy tube or the like. The HME can have an axial configuration with a cylindrical outer housing that houses the HME elements and has a female connection port on one end and a male connection port on the other end, and may be connected to a breathing circuit or left open when the patient is breathing on their own. Thus, the housing of the HME projects outward, and generally axially, beyond the machine end of the tracheostomy tube.

[0005] The "Thermovent T" sold by Smith's Medical has a different T-shaped configuration with two HME elements mounted on either end of a straight tubular housing that extends laterally from a connection port through which the device fits over a tracheostomy tube or the like. The tubular housing of the HME elements may be curved to follow the anatomical contours of the neck as described in EP 1888157.

[0006] Both axial and T-shaped HMEs have an HME element or elements contained in a portion of the HME housing that protrudes outside of the tracheostomy tube or other breathing device. When the patient is spontaneously breathing and not connected to a breathing circuit, the HME increases the distance of the protrusion from the stoma, making it more visible and more likely to catch on clothing or bedding, causing the tracheostomy tube to become displaced and causing discomfort to the patient. Conventional HMEs also have the disadvantage of introducing additional dead space into the gas flow path to and from the patient. The tapered slip fit between the HME coupling and the machine end connector on the breathing device means that the HME must be twisted relative to the connector. This necessarily causes some twisting motion of the tracheostomy tube itself when the HME is removed and replaced. This can cause discomfort to the patient. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] British Patent No. 2391816 [Patent Document 2] WO 01 / 72365 [Patent Document 3] U.S. Patent No. 5,505,768 [Patent Document 4] Swedish Patent No. 516666 [Patent Document 5] U.S. Patent No. 3,881,482 [Patent Document 6] German patent no. 20302580 [Patent Document 7] German Utility Model No. 20114355 [Patent Document 8] International Publication No. 97 / 01366 [Patent Document 9] US Patent Application Publication No. 2002 / 0157667 [Patent Document 10] U.S. Patent No. 6,422,235 [Patent Document 11] European Patent No. 1208866 [Patent Document 12] U.S. Patent No. 4,971,054 [Patent Document 13] European Patent No. 1699515 [Patent Document 14] U.S. Patent No. 5,035,236 [Patent Document 15] European Patent No. 535016 [Patent Document 16] U.S. Patent No. 5,647,344 [Patent Document 17] British Patent No. 2267840 [Patent Document 18] European Patent No. 856327 [Patent Document 19] European Patent No. 1699515 [Patent Document 20] U.S. Patent No. 7,363,925 [Patent Document 21] WO 15 / 107320 [Patent Document 22] US Patent Application Publication No. 2008 / 0099013 [Patent Document 23] British Patent No. 2540456 [Patent Document 24] European Patent No. 1888157 Summary of the Invention [Problem to be solved by the invention]

[0008] It is an object of the present invention to provide alternative HME devices, HME elements, and assemblies of respiratory devices and HME devices. [Means for solving the problem]

[0009] According to one aspect of the invention there is provided an HME device of the above kind, characterised in that the HME element is arranged such that a majority of its length extends into a cooperating connector on the respiratory device.

[0010] The outer housing of the HME device preferably has a tapered inner surface adapted to fit over the outer side of the cooperating connector. The outer side of the HME element is preferably spaced from the inner surface of the outer housing along at least its patient end to define an annular recess at the patient end of the device. At least the machine end of the cooperating connector can be received in the annular recess such that at least the patient end of the HME element is located within the cooperating connector. When the HME device is fitted over the connector, the HME element is removable from the outer housing of the HME device from the machine end of the outer housing. The HME element can be held to the outer housing by a clip fitting. The clip fitting is releasable from the outer housing by pulling it away from the outer housing without the need to twist the element relative to the housing. The HME device can be coupled to the machine end of the inner cannula such that the HME device and the inner cannula can be removed and replaced as a single unit.

[0011] According to another aspect of the invention, there is provided an HME element for an HME device according to the above aspect of the invention.

[0012] According to a further aspect of the invention there is provided an assembly of a patient respiratory device and an HME device according to the above aspect of the invention, characterised in that the patient respiratory device has a male connector at its machine end, an outer housing of the HME device fitting over the connector and at least a portion of the HME element extending into the connector.

[0013] An HME device, an HME element and assembly of the HME device on a tracheostomy tube, all according to the present invention, will now be described by way of example with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of a tracheostomy tube assembly fitted with an HME device at the machine end. [Diagram 2] FIG. 2 is an enlarged cross-sectional side view of the machine end of the assembly of FIG. 1. [Diagram 3] FIG. 2 is a perspective view of the assembly with the HME element removed from the outer housing of the HME device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1 and 3, there is shown an assembly of a tracheostomy tube 1. The assembly has an HME device 2 fitted over its rear, machine end 10. The tracheostomy tube 1 may be conventional having a curved shaft 11 that opens into its forward, patient end 12. The rear, machine end 10 of the shaft 11 is coupled with a conventional 15mm tapered male connector 13 and a radially extending neck flange 14.

[0016] The HME device 2 differs from conventional HMEs in that the HME device 2 is positioned such that the majority of the length of its HME element 20 is contained within the length of the tracheostomy tube connector 13. In particular, the HME 2 comprises an outer housing 21 and a removable HME fitting 22 formed from an HME element 23 and an end cap 24. The outer housing 21 has a tubular or cylindrical shape with a circular section and is molded from a hard plastic. The housing 21 has an inner tapered inner surface 26 that tapers gradually to a larger diameter at its patient end and is configured to make a tapered slip fit over the exterior of the male connector 13 on the tracheostomy tube 1. Towards a rearward, machine end 27, the housing 21 has a radially projecting knurled flange 28 spaced from the machine end of the housing by a short axially projecting sleeve 29. The outer surface of the sleeve 29 is molded with a number of radially projecting pips or projections 30 spaced about the circumference of the sleeve to function as part of the clip fitting. The end cap 24 has a circular opening 31 which occupies a majority of the diameter of the cap. The cap 24 has a forwardly projecting collar 32 which has an inside diameter equal to the outside diameter of the sleeve 29. The inner surface of the collar 32 also has an annular groove 33 about its periphery, the width and depth of which are sufficient to receive the pips 30 on the sleeve 29. The engagement of the pips 30 in the groove 33 is sufficient to retain the cap 24 on the housing 21.

[0017] The end cap 24 is firmly joined to the machine end of the HME element 23. The HME element 23 has a circular cross section and is generally cylindrical. The HME element 23 has an enlarged machine end portion 34 with an outwardly flared machine end portion 35 and a central portion 36 that is a constant circular portion that extends for most of the length of the element 23. A short forward, patient end portion 37 is of reduced diameter and connects to the central portion 36 by a tapered region 38. The element 23 is longer than the outer housing 21 such that the patient end portion 37 protrudes beyond the patient end of the outer housing. The enlarged machine end portion 34 fits snugly and sealingly against the inside of the machine end of the outer housing 21. The portion of the HME element 23 forward of the machine end portion 34 is spaced along its length from the inside of the outer housing 21 by an annular recess 40. The size and shape of the annular recess 40 is selected to receive a majority of the length of the connector 13 on the tracheostomy tube 1. Thus, the outer surface of the HME element 23 is a tight, sealing fit within the forward, patient end of the connector 13. Towards the rearward, machine end, the connector 13 is slightly enlarged internally and formed with an internal sealing ring 41 adapted to sealingly contact the exterior of the element 23.

[0018] The HME element 23 may be of any conventional type, such as a coiled strip of corrugated cardboard treated with a hygroscopic salt, or a foamed plastic coated with a hygroscopic substance. The HME element 23 may include a filter, such as an enlarged machine end portion 34. The HME element 23 may be wrapped around its curved surfaces with a flexible plastic material to enhance the seal between the outside of the element and the inside of the connector 13.

[0019] 1 and 2, with the HME device 2 fitted over the tracheostomy tube 1, the HME element 23 occupies substantially the entire length of the interior of the connector 13. When the patient inhales, air is drawn through the HME element 23, through the HME device 2 and the connector 13, and into the lumen of the tracheostomy tube 1. Exhaled gases flow back in the reverse direction, imparting most of their heat and moisture to the HME element 23 for transfer to the next inspiration.

[0020] By locating the HME element 23 to extend into the connector 13 on the tracheostomy tube 1, the length of the HME protruding from the tube can be substantially reduced, making the overall assembly less bulky compared to conventional HMEs. This makes the tracheostomy assembly itself less noticeable. The smaller profile also reduces the risk of the machine end of the assembly catching on bedding, clothing, etc. By moving the center of mass of the HME closer to the patient's neck, the impact of the HME on the tube can be reduced compared to conventional HMEs. Another advantage of having the HME element extend into the connector is that it reduces dead space in the assembly. In conventional assemblies, the dead space includes the internal volume of the connector above the tube and the volume of the HME element itself in the connected HME housing. In contrast, in the configuration of the present invention, the dead space is only due to the internal volume of the tube on the patient side of the HME element. By reducing the dead space, the volume of exhaled air that does not pass through the HME element that is returned to the lungs during inspiration is reduced.

[0021] The HME device 2 can be fitted and removed in its entirety onto the connector 13 by a twisting and slipping motion. However, when replacement is required, instead of removing the entire device 2, only the HME element 23 and its associated end cap 24 need to be removed. This is done without any twisting motion by simply pulling the end cap 24 away from the outer housing 21 and the connector 13 as shown in FIG. 3. This releases the end cap 24 from the pip 30 on the outer housing 21 of the HME device 2. This arrangement has the advantage of avoiding the need to apply a twisting torque to the tube 1, thereby reducing trauma and discomfort to the patient. In this way, the HME element can be removed and replaced every 24 hours or as needed, with reduced discomfort to the patient. If access to the tube is required for suction or the like, this can also be done by removing only the central HME element, leaving the outer HME housing in place. Another advantage is that the replaceable element allows the outer housing to be reused multiple times, thus reducing the amount of plastic used. This reduces overall costs and reduces the amount of waste plastic produced, which reduces damage to the environment and saves some of the costs of disposing of clinical waste. Tracheostomy tubes and the like that are arranged to receive an HME of the type of the present invention can still be connected to a conventional female tapered connector on the end of a gas delivery tube when ventilation is required, simply by removing the entire HME.

[0022] The HME may be coupled to the machine end of an inner cannula adapted to extend along the lumen of the tracheostomy tube. The inner cannula is of a type that is removed and replaced to avoid accumulation of secretions in the outer tube. In such a configuration, the HME is removed and replaced as a single unit with the inner cannula.

[0023] It is not necessary that the HME element be removable from the outer housing, as the HME element may be permanently attached to the outer housing and the entire device must be removed when it needs to be replaced.

[0024] The present invention is not limited to HME devices for use with tracheostomy tubes, but may also be used with other respiratory devices such as endotracheal tubes, laryngeal masks, and face masks.

Claims

1. 1. An HME device (2) comprising an outer housing (21) and at least one HME element (20) attached to the outer housing, the HME device (2) being arranged to mate with a cooperating connector (13) on a respiratory device (1), the HME device (2) being arranged such that a majority of the length of the HME element (20) extends within the cooperating connector (13) on the respiratory device (1).

2. 2. The HME device of claim 1, wherein the outer housing (21) of the HME device (2) has a tapered inner surface (26) adapted to fit over the outside of the cooperating connector (13).

3. 3. The HME device of claim 1 or 2, wherein the outer side of the HME element (20) is spaced from the inner surface of the outer housing (21) at least along its patient end so as to define an annular recess (40) at the patient end of the device (2), and wherein at least the machine end of the cooperating connector (13) can be received within the annular recess (40) so that at least the patient end of the HME element (20) is located within the cooperating connector (13).

4. 3. An HME device as described in claim 1 or 2, characterized in that when the HME device is fitted onto a connector (13), the HME element (20) is removable from the outer housing (21) of the HME device (2) from the machine end of the outer housing (21).

5. 5. The HME device of claim 4, wherein the HME element (20) is held to the outer housing (21) by a clip fitting (29, 30), the clip fitting being releasable from the outer housing (21) by pulling the element (20) away from the outer housing (21) without the need to twist the element (20) relative to the housing (21).

6. 3. The HME device of claim 1 or 2, wherein the HME device (2) is coupled to the machine end of the inner cannula such that the HME device and inner cannula can be removed and replaced as a single unit.

7. An HME element (20) for an HME device (2) according to claim 1 or 2.

8. 3. An assembly of a patient breathing device (1) and an HME device (2) as claimed in claim 1 or 2, characterized in that the patient breathing device (1) has a male connector (13) at its machine end, the outer housing (21) of the HME device (2) fits onto the outside of the male connector (13), and at least a portion of the HME element (20) extends into the male connector (13).

9. 9. An assembly according to claim 8, wherein the patient breathing device is a tracheostomy tube (1).

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