PAEDIATRIC CUVETTE

Abstract

A gas sampling assembly comprising an insert and a cuvette, and an insert for use in a cuvette, suitable for sampling respiratory gases of paediatric patients, the insert comprising a unitary insert having a hub and at least two extending members extending outwardly from the hub, the at least two extending members defining a void therebetween and the insert being located, in use, at least partially within the sampling channel, and the gas sampling cell assembly being configured such that light passing through the optical window passes into the sampling channel and through the void between the two extending members.

Claims

1. (canceled)

2. A unitary insert for use in conjunction with a gas sampling cell, the unitary insert comprising a hub and at least two extending members extending outwardly from the hub, the at least two extending members defining a void therebetween and the insert being locatable, in use, at least partially within the sampling channel of a gas sampling cell.

3. The insert of claim 2, wherein the insert is formed of a resilient material.

4. (canceled)

5. The insert of claim 2, wherein the hub has a cross-sectional shape which is substantially circular, square, rectangular, polygonal or oval.

6. The insert of claim 5, wherein one or more of the sides of the cross-sectional shape are arcuate.

7. The insert of claim 2, wherein the hub comprises an aperture through which, in use, respiratory gases pass.

8. The insert of claim 2, wherein the at least two extending members are not connected together at an end distal to the hub.

9. The insert of claim 2, wherein an inner surface of each of the at least two extending members comprises a substantially straight or planar section at the end distal to the hub, and a curved or arcuate section at the end proximal to the hub.

10. The insert of claim 9, wherein the arcuate shapes of the proximal ends of two extending members are connected together such that they form a continuous curve.

11. The insert of claim 2, wherein the at least two extending members are substantially parallel.

12. The insert of claim 2, wherein at least one of the at least two extending members comprise clipping means at or near the end distal to the hub.

13. The insert of claim 12, wherein the clipping means comprise a nub extending radially outwardly from the distal end of the extending member.

14. The insert of claim 2, wherein the hub further comprises one or more projections extending outwardly from the hub.

15. The insert of claim 14, wherein the one or more projections comprise an annular collar.

16. The insert of claim 15, wherein the one or more projections comprise at least two protrusions extending outwardly from opposing sides of the insert.

17. The gas sampling cell assembly of claim 20, wherein the insert occupies from 1% to 50% of the internal volume of the cuvette.

18. The gas sampling cell assembly of claim 20, wherein the cuvette comprises two optical windows.

19. A kit of parts comprising a cuvette and at least one insert, the cuvette comprising an inlet, a sampling channel, an outlet and at least one optical window and being configured such that a gas sample passes from the inlet, through the sampling channel and to the outlet, and the at least one insert comprising a unitary insert having a hub and at least two extending members extending outwardly from the hub, the at least two extending members defining a void therebetween and the insert being insertable into the cuvette such that it is located, in use, at least partially within the sampling channel and configured such that light passing through the optical window passes into the sampling channel and through the void between the two extending members.

20. A gas sampling cell assembly comprising a cuvette and an insert, the cuvette comprising an inlet, a sampling channel, an outlet, and at least one optical window, wherein the cuvette is configured such that a gas sample passes from the inlet, through the sampling channel and to the outlet, and the insert comprises the unitary insert of claim 2.

21. The gas sampling cell assembly of claim 20, wherein at least a portion of the outer walls of the hub are shaped to correspond to at least a portion of the shape of internal walls of the gas sampling cell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention will now be described in more detail, by way of example only, with reference to the following Figures:

[0030] FIG. 1 is a front view of an embodiment of the insert according to the invention;

[0031] FIG. 2 is a side view of the insert of FIG. 1;

[0032] FIG. 3 is the insert of FIG. 1 or 2 retained within a cuvette;

[0033] FIG. 4 is a cross-sectional view of the insert of FIG. 1 or 2 inside a cuvette, with the cross-section taken along the line X-X as shown in FIG. 2.

DETAILED DESCRIPTION

[0034] An insert 10 according to the invention can be seen in FIG. 1. The insert comprises a hub 101 from which two extending members 102, 103 protrude downwardly, forming a void 109 therebetween. The two extending members each comprise an arcuate inner edge 104 at the end proximal to the hub. The two extending members are connected together at the proximal end such that they form a continuous curve. The continuous curve forms an intermediate portion of a continuous wall extending from the distal end of one extending member to the distal end of a second extending member, forming a U shape along their internal edge 104. Each of the two extending members 102, 103 comprises a nub 105, 106 at the end of the extending member 102, 103 distal to the hub. The nub 105, 106 extends outwardly from the distal ends of the extending members 102, 103.

[0035] The hub 101 comprises a first protrusion 107 and a second protrusion (108; see FIG. 2), the two protrusions extending outwardly from the hub on opposing sides and forming shoulders for engagement with the cuvette (not shown). The hub additionally comprises an annular ring or collar 111 which extends radially outwardly from at least a portion of the hub 101, the outer edge of the annular ring or collar 111 being shaped to correspond to the shape of an internal wall of the cuvette (not shown). The annular ring or collar 111 is positioned directly above the first and second protrusions 107, 108. At least a portion of the hub 101 is tubular, and substantially cylindrical in shape, with the shape of the outer wall of the hub corresponding to the shape of the internal wall of the cuvette into which it is to be inserted.

[0036] The insert 10 has been injection moulded in a single step, and is formed from a unitary piece of plastics material.

[0037] A side view of the insert can be seen in FIG. 2, in which the two protrusions 107, 108 extending outwardly from opposing sides of the hub 101 are visible.

[0038] The insert 10, when inserted within a cuvette 301, can be seen in FIG. 3. The cuvette is shaped such that the internal diameter of the cuvette in the gas sampling channel 302 is smaller than the internal diameter of the cuvette in either the inlet 303 or the outlet 304. Within the cuvette, a first shoulder 305 is present where the internal diameter changes between the inlet 303 and the gas sampling channel 302, and a second shoulder 306 is present where the internal diameter changes between the gas sampling channel 302 and the outlet 304. The first and second protrusions 107, 108 on the hub 101 of the insert 10 abut the first shoulder 305, while the nubs 105, 106 abut the second shoulder 306, securely holding the insert 10 in position within the cuvette 301.

[0039] During insertion of the insert 10 into the cuvette 301, pressure from the internal walls of the cuvette 301 causes the two extending members 102, 103 to flex inwardly, enabling them to pass through the narrower gas sampling channel 302. Once the nubs 105, 106 on the two extending members 102, 103 have passed through the gas sampling channel 302 and into the wider outlet 304, the two extending members 102, 103 return to their original positions, causing the nubs 105, 106 to hook around and abut the second shoulder 306. Thus, the insert 10 is prevented from further insertion into the cuvette 301 by the abutment of the protrusions 107, 108 against the first shoulder 305, and is prevented from return movement by the abutment of the nubs 105, 106 against the second shoulder 306, effectively retaining the insert 10 in place within the cuvette 301.

[0040] The cuvette further comprises two opposing optical windows 307 through which infrared light is passed in order to measure CO.sub.2 levels in respiratory gases. The optical window 307 is aligned with the void 109 formed between the two extending members 102, 103. Thus, the insert 10 does not prevent the passage of infrared light through the cuvette 301, and the elongate shape of the void 109 means that small longitudinal movements of the insert 10 within the cuvette 301 will not lead to occlusion of the optical window 307 by the insert 10.

[0041] A cross-section of the insert 10 and cuvette 301 is shown in FIG. 4, with the cross-section taken along the line indicated X-X in FIG. 2. In addition to the features previously discussed, this view shows the interior of the hub 101. The interior of the hub 101 comprises a lumen 401 through which respiratory gases can pass, allowing incoming respiratory gases to pass from the inlet 303, through the gas sampling channel 302 and to the outlet 304. This lumen 401 has a smaller diameter compared to the internal diameter of the cuvette inlet 303 and gas sampling channel 302, making it more suitable for the transfer of the low volumes of respiratory gases seen in paediatric patients.