GB2177006A

GB2177006A - Feeding system

Info

Publication number: GB2177006A
Application number: GB08615134A
Authority: GB
Inventors: Orlando D Cambio; Earl Richard Refsland
Original assignee: Kendall Co
Current assignee: Kendall Co
Priority date: 1985-06-21
Filing date: 1986-06-20
Publication date: 1987-01-14
Also published as: FR2583644A1; GB8615134D0; NL8601611A; JPS61293473A; CA1274146A; GB2208608A; DE3620066A1; GB2206803B; GB8814935D0; GB2177006B; AU5899686A; GB2208608B; GB2206803A; GB8814934D0

Abstract

A feeding system 18 for connecting a humidifier 10 to a reservoir 16 comprising, a first elongated conduit 62 for feeding water from the reservoir to the humidifier, a second elongated conduit 68 alongside the first conduit for passing air from the humidifier to the reservoir, with an upstream end of the first and second conduits being connected in fluid communication to the reservoir. The conduits are connected to the humidifier with a downstream end of the first and second conduits located inside the humidifier, and with the downstream end of the first conduit being located adjacent the downstream end of the second conduit. <IMAGE>

Description

SPECIFICATION Feeding System The present invention relates to a liquid feeding system for a humidifier.

Humidifiers in a breathing circuit for a patient are known. In such systems, a sterile liquid is placed in the humidifier with the liquid being heated, and an air mixture is passed from a ventilator through the liquid in order to heat and humidify the air mixture, and the resulting air mixture is passed to the patient.

However, during use of the humidifier the liquid is utilized to humidify the air mixture, and it is necessary to periodically replenish the liquid in the humifier. In the past, the humidifier was normally taken apart, and additional liquid was poured into the humidifier. It has been found that this procedure is inconvenient, and poses the possibility of contaminating the liquid due to handling of the liquid. Other procedures are to pour water through one of the ports of a cap for the humidifer.

Alternatively, water can be fed from a suspended flexible solution bag through a special set. The disposable set, which is manufactured by a company, consists of a tee adapter which fits over the cascade outlet. The patient hose is connected to the perpendicular leg of the tee and the remaining leg is connected to the solution bag via a vinyl tube.

Water is delivered through the adapter to the cascade by opening a tube clamp when required.

Although the filling process is simplified it is still manual requiring frequent attention. Further, versions of the humidifier offer a special port for inserting a water feed system. The system, manufactured by a company, is composed of a suspended glass bottle which feeds the water through a large bore tube to a valve assembly which is positioned within the cannister. The value is automatically closed when the water level reaches the required height. Although the system continuously feeds water as needed, the set-up must be cleaned and sterilized for re-use.

A principal feature of the present invention is the provision of a feeding system for connecting a humidifier to a reservoir.

The feeding system comprises first elongated conduit means for feeding water from the reservoir to the humidifier, second conduit means alongside the first conduit means for passing air from the humidifier to the reservoir, and means for connecting an upstream end of the first and second conduit means in fluid communication to the reservoir. The system has means for connecting the conduit means to the humidifier with a downstream end of the first and second conduit means located inside the humidifier, and with the downstream end of the first conduit means being located adjacent the downstream end of the second conduit means.The system preferably has an elbow connected to the first and second conduit means and having a hollow first part surrounding and spaced from the first and second conduit means, and a hollow second part in fluid communication with the first part and extending at an angle to the longitudinal axes of the first and second conduit means. A downstream end portion of the first and second conduit means may extend through and from the elbow to a location inside the humidifier.

A preferred feature of the present invention is that the outside diameter of the first conduit means is substantially smaller than the outside diameter of the second conduit means in order to make the first conduit means as small as possible and the second conduit means as large as possible without obstructing passage of humidified air through the elbow to the patient.

Another preferred feature of the invention is that the downstream end of the second conduit means is formed at an angle relative to the longitudinal axis of the second conduit means in order to break surface tension and drain a lower part of the second conduit means during use of the system.

Yet another preferred feature of the invention is that at least a portion of the downstream end of the second conduit means is located below the downstream end of the first conduit means to facilitate rapid initial filling of the humidifier.

The present invention may be put into practice in various ways and one specific embodiment will be described by way of example to illustrate the invention with reference to the accompanying drawings, in which; Figure 1 is a fragmentary plan view of a humidifying system according to the present invention; Figure 2 is a sectional view of a humidifier for use in the system shown in Figure 1; Figure 3 is a fragmentary sectional view of a feeding system for use in the system shown in Figure 1; Figure 4 is a fragmentary perspective view of a lower portion of a reservoir for use in the system shown in Figure 1; Figure 5 is a perspective view of a clip for the reservoir shown in Figure 4; and Figure 6 is a perspective view illustrating upstream ends of conduits for placement in a lower part of the reservoir.

Referring now to Figures 1 to 3, there is shown a humidifying system generally designated 10 comprising a ventilator 12 of known type, a humidifier 14 of known type, a reservoir 16 for retaining sterile water, and a feeding system 18 according to the present invention.

As shown, the humidifier 14 has a bowl 20 to retain a supply of sterile water W in a lower part thereof, and a lid 22 releasably attached to an upper part of the bowl 20 by suitable means such as threads 24, with the bowl 20 and lid 22 defining a chamber 25. The humidifier 14 also has a heater 26 of known type in order to heat the water W in the humidifier 14. The humidifier 14 has an inlet port 28 of an elongated tubular section 30 with a lower part of the tubular section 30 located beneath the level of the water W, and with the lower part of the tubular section 30 having apertures 32 to permit passage of gas therethrough.The humidifier 14 has an annular flange 34 extending from a side of the tubular section 30 toward a central portion of the bowl 20, with an upper wall or sparger plate 36 being located alongside the tubular section 30 above the annular flange 34 and having a plurality of relatively small apertures 38 for a purpose which will be described below. As shown, the sparger plate 36 is located beneath the level of the water W. The humidifier 14 also has a tubular section 40 on the lid 22 defining an outlet port 42.

The system 10 has a corrugated tube 44 connected to an outlet 46 of the ventilator 12 to the inlet port 28 of the humidifier 14. In use, the ventilator 12 delivers a volume of gas, such as an oxygen mixture, in cycles with the pressure and volume being controlled in order to simulate the normal breathing mechanism of a patient. The gas is delivered through the tube 44 and tubular section 30 into the water W and through the apertures 32 to a location intermediate the flange 34. The gas then passes through the apertures 38 of the sparger plate 36 and through the water to a location above the level of the water W. The sparger plate 36 provides improved mixing of the gas with the water, and breaks up the gas flow to avoid large bubbles. As the gas passes through the water W and the sparger plate 36 it is humidified by the water W.Also, the heater 26 heats the water W, and the heated water in turn heats the gas while passing through the water W. The heated and humidified gas passes along the surface of the water W and through the outlet port 42 to the patient, as will be further described below The reservoir 16 is suspended by suitable means, such as a hook 48, received in an upper ring 50 of the reservoir 16 at a location above the humidifier 14. The reservoir 16 has an outer wall 52 defining a chamber 54 to retain sterile water or liquid L which is fed to the humidifier 14, as will be described below. With reference to Figures 4 and 6, the reservoir 16 has a pair of lower openings 56 and 58, and a downwardly extending protuberance 60 adjacent the openings 56 and 58.

With reference to Figures 3 and 6, the feeding system 18 of the present invention has first water conduit means 62 having an upstream end 64 connected to the reservoir 16, and a downstream end 66 received in the humidifier 14. The feeding system 18 also has second gas conduit means 68 having an upstream end 70 connected to the reservoir 16, and a downstream end 72 received in the humidifier 14. The feeding system 18 has an elbow 74 having a hollow first cylindrical part 76 extending around and spaced from the first and second conduit means 62 and 68, and a hollow cylindrical second part 78 communicating with the first part 76 and extending at approximately a 90 degree angle to the longitudinal axes of the first and second conduit means 62 and 68.The elbow 74 has first and second upwardly directed hollow nipples 80 and 82, and third and fourth downwardly directed hollow nipples 84 and 86, with the first nipple 80 communicating with the third nipple 84 and with the second nipple 82 communicating with the fourth nipple 86. As shown, the nipples 80~86 are located above the first and second parts 76 and 78 of the elbow 74.

The first conduit means 62 has an upstream tubular section 88 with a downstream end 90 received on the first nipple 80. The tubular section 88 has an upstream end terminating in a spike 92 for connecting the tubular section 88 in fluid communication to the reservoir 16 through the opening 58. The tubular section 88 also has an outwardly directed flange 94 adjacent the spike 92 to limit movement of the tubular section 88 into the reservoir 16. The second conduit means 68 has an upstream tubular section 96 having a downstream end 98 connected to the second nipple 82. The tubular section 96 has a hollow spike 100 for connecting the second conduit means 68 to the reservoir 16 through the opening 56. The tubular section 96 has an outwardly directed flange 102 adjacent the spike 100 to limit movement of the spike 100 into the reservoir 16.

As shown in Figure 3, the downstream ends of the first and second conduit means 62 and 68 are defined by a co-extruded double lumen tubular section 104 having a first tube 106 of the first conduit means 62 with an upstream end 108 received on the third nipple 84, and a second tube 110 of the second conduit means 68 having an upstream end 112 received on the fourth nipple 86.

In use of the system 10, the first part 76 of the elbow 74 is attached to the tubular section 40 of the humidifier 14, and in this configuration, the tubular section 104 extends through the first part 76 of the elbow 74 to a location substantially below the elbow 74 into the bowl 20 of the humidifier 14.

As shown in Figure 3, the outside diameter of the first tube 106 is substantially smaller than the outside diameter of the second tube 110, with the inside diameter of the first tube 106 being made as small as possible, and the inside diameter of the second tube 110 being made as large as possible for purposes which will be described below. In a preferred form, the internal diameter of the firsttube 106 is approximately .080 inches (2 mms) in diameter, the internal diameter of the second tube is approximately .260 inches (6.6 mms) in diameter, and the internal diameter of the first part 76 of the elbow 74 is approximately .730 inches (18.5 mms) in diameter which is greater than the width of the tubular section 104 which is approximately .470 inches (11.9 mms).

The ratio of the internal diameter of the first tube 106 to the second tube 110 is thus 0.08:0.26 i.e.

1:3.25, or more broadly is preferably in the range 1:2 to 1:5 or more preferably at least 1:3. The ratio of the internal diameter of the section 76 to the width of the tubular section 104 is .73:.47 i.e. 1.55:1 or more broadly is preferably at least 1.5:1. Also, the downstream end 72 of the second conduit means 68 is formed at an angle of less than 60 degrees e.g. 30 to 60 and preferably approximately 45 degrees to the longitudinal axis of the second conduit means 68 for a purpose which will be described below. The downstream end of the first conduit means 62 is formed with at an angle of approximately 90 degrees to the longitudinal axis of the first conduit means 62. As shown, the lowermost portion of the angle formed part of the downstream end 72 of the second conduit means 68 is located adjacent the downstream end 66 of the first conduit means 62, and the downstream end 66 of the first conduit means 62 is preferably located intermediate the lower and upper portions of the angle formed part of the second conduit means 68.

In a further description of the use of the system 10, with reference to Figures 1 to 3, a corrugated tube 114 is connected to the second part 78 of the elbow 74 and extends to the patient. When the first part 76 of the elbow 74 is connected to the tubular section 40 of the humidifier 14, the heated humidified gas passes through the outlet port 42, the first and second parts 76 and 78 of the elbow 74 and through the tube 114 to the patient for therapy.

With reference to Figures 4 and 5, the system 10 has a clip 116 to retain the first and second conduit means 62 and 68 to the reservoir 16. The clip 116 has a first hook portion 118 at one end of the clip 116 received on the first and second conduit means 62 and 68 adjacentthe flanges 94and 102. The clip 116 has a second hook portion 120 at the other end of the clip 116 extending partially around the protuberance 60 of the reservoir 16. The clip 116 has a central portion 122 connecting the first and second hook portions 118 and 120. The first hook portion 118 may first be secured about the first and second conduit means 62 and 68, and the second hook portion 120 may then be secured about the protuberance 60 of the reservoir 16.In this manner, the clip 116 retains the first and second conduit means 62 and 68 in the reservoir 16 to prevent accidental pulling out of the first and second conduit means 62 and 68 for a purpose which will be described below. The clip 116 may be made of any suitable material, such as metal.

During use of the system 10, the water W which is utilized to humidify the gas which passes to the patient reduces the water level in the bowl 20 of the humidifier 14 and, in the past, it was necessary to periodically replenish the supply of water W in the humidifier 14. The procedure would normally be carried out by removing the lid 22 from the bowl 20, and pouring water into the bowl 20 to raise the level of water in the bowl 20. It has been found that this procedure is inconvenient, and also poses the possibility of contamination to the water which is poured into the bowl 20 during handling. Other methods of filling are disclosed on page 1.

In accordance with the present invention, the feeding system 18 automatically feeds water from the reservoir 16 to the bowl 20 of the humidifier 14 in order to maintain the desired level of water W in the humidifier 14. When the level of water W is below the downstream end 72 of the second conduit means 68, gas passes through the tube 110 and second conduit means 68 and bubbles up through the liquid L in the reservoir 16, while water passes downwardly through the first conduit means 62 and the tube 106 into the humidifier 14. However, when the water rises in the humidifier 14 and closes off the second conduit means 68, the water continues flowing for a time from the reservoir 16 through the first conduit means 62 into the humidifier 14, and develops a vacuum above the head of liquid L in the reservoir 16.In order for the liquid to stop flowing downwardly from the reservoir 16, it is necessary for the vacuum in the reservoir to reach a negative pressure equal to the hydrostatic head in which case the system is at equilibrium. Meanwhile, the water in the humidifier 14 has closed off the second conduit means 68, and water starts rising in the second conduit means 68. The second conduit means 68 fills with water and the system reaches equilibrium.

During further use of the system 10, water is utilized to humidify the gas passing to the patient, and the water level eventually drops below the downstream end 72 of the second conduit means 68. At this time, surface tension initially prevents gas from passing up the second conduit means 68, but angle formed downstream end 72 of the second conduit means 68 breaks the surface tension in order to drain the second tube 110 of the second conduit means 68. After the second tube 110 has drained, there exists a greater pressure acting on the lower part of the remaining column of water in the second conduit means 68 than its hydrostatic head, such that the water flows into the reservoir 16, after which normal flow of water begins again through the first conduit means 62, and gas passes upwardly through the second conduit means 68.

In accordance with the present invention, the first tube 106 is made as small as possible in diameter, and the second tube 110 is made as large as possible in diameter while minimizing restriction of gas flow th roughthe elbow 74 and outlet port 42 to the patient. The first and second tubes 106 and 110 are made of the desired sizes while permitting water feeding of the system 18 from the reservoir 16 to the humidifier 14.

As shown in Figure 1, the system 18 has a pair of clamps 124 and 126 which may be utilized before the initial filling of the humidifier 14, and while changing reservoirs 16 to close off the first and second conduit means 62 and 68. Of course, the clamps 124 and 126 are open during use of the system to permit passage of liquid and gas through the first and second conduit means 62 and 68.

It is desirable to use the feeding system 18 in connection with the reservoir 16 to initially fill the humidifier 14 to the desired level. If the humidifier 14 was filled through the relatively small first conduit means 62, it would require an extended period of time, such as twenty-five minutes, to reach the desired liquid level in the humidifier 14. Thus, it is desirable to initially fill the humidifier 14 through the relatively large second conduit means 68, and the liquid exists at the lower edge of the formed downstream end 72 of the second conduit means 68, while gas passes through the first conduit means 62.However, if the downstream ends of the first and second conduit means 62 and 68 were on a straight slant, the water exiting from the second conduit means 68 would be pulled up into the first conduit means 62 which would slow down and possibly stop filling of the humidifier 14 since gas would not be passing up through the first conduit means 62.

Hence, in accordance with the present invention, the first conduit means 62 has its downstream end 66 spaced slightly above the lowermost part of the formed downstream end 72 of the second conduit means 68 to preventwaterfrom passing up into the first conduit means 62 which is being utilized as a gas tube during initial filling of the humidifier 14.

The downstream end 66 is formed at an angle of 40 to 90 degrees to the longitudinal axis of the first conduit means, and preferably at an angle of 90 degrees.

As previously discussed, with reference to Figures 4 to 6 the clip 116 engages against the flanges 94 and 102 of the first and second conduit means 62 and 68 and prevents the first and second conduit means 62 and 68 from pulling out of the reservoir 16. In the event that one of the conduit means 62 or 68 would inadvertently become detached from the reservoir 16 during use of the system 10, there would be a massive leakage of air into the reservoir 16 and passage of liquid out through the exposed associated opening 58 or 56. Also, there would be a continuous stream of water through the remaining connected conduit means 62 or 68 into the humidifier 14, and the ventilator 12 could pump part of the overfilled water in the humidifier 14 through the tube 114 into the lungs of the patient, which might result in drowning of the patient or other harmful results Thus, the clip 116 prevents the harm which could occur to the patient in the event that one of the conduit means 62 and 68 should become detached from the reservoir 16.

The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

Claims

1. A feeding system for connecting a humidifier to a reservoir, comprising: first elongated conduit means for feeding water from the reservoir to the humidifier; second elongated conduit means alongside the first conduit means for passing air from the humidifier to the reservoir; means for connecting an upstream end ofthefirst and second conduit means in fluid communication to the reservoir; and means for connecting the conduit means to the humidifier with a downstream end of the first and second conduit means located inside the humidifier, with the downstream end of the first conduit means being located adjacent the downstream end of the second conduit means, and with the downstream end of the second conduit means is formed at an angle relative to the longitudinal axis of the second conduit means.

2. A system as claimed in Claim 1 in which the downstream end is cut off at a single angle through the second conduit means relative to the longitudinal axis of the second conduit means.

3. A system as claimed in Claim 1 or Claim 2 in which the angle is less than 60 degrees.

4. A system as claimed in Claim 1,2 or 3 in which the angle is approximately 45 degrees.

5. A system as claimed in Claim 1,2,3 or 4 in which the downstream end of the first conduit means is located upstream of at least a portion of the second conduit means.

6. A system as claimed in any one of Claims 1 to 5 in which the lowermost part of the downstream portion of the second conduit means is located adjacent the first conduit means.

7. A feeding system for connecting a humidifier to a reservoir, comprising: first elongated conduit means for feeding water from the reservoir to the humidifier; second elongated conduit means alongside the first conduit means for passing air from the humidifier to the reservoir; means for connecting an upstream end of the first and second conduit means in fluid communication to the reservoir; and means for connecting the conduit means to the humidifier with a downstream end of the first and second conduit means located inside the humidifier, with the downstream end of the first conduit means being located adjacent the downstream end of the second conduit means, and with at least a portion of the downstream end of the second conduit means being located on one side of and below the downstream end of the first conduit means.

8. A system as claimed in Claim 7 in which the downstream end of the second conduit means is formed at an angle relative to the longitudinal axis of the second conduit means.

9. A system as claimed in Claim 7 or Claim 8 in which a lowermost part of the second conduit means is located adjacent the first conduit means.

10. A system as claimed in Claim 7,8 or 9 in which the first conduit means is formed at an angle of approximately 90 degrees to the longitudinal axis of the first conduit means.

11. A system as claimed in Claim 8 in which the downstream end of the first conduit means is located intermediate an upper and lower portion of the formed part of the second conduit means.

12. A system as claimed in Claim 8 in which the first conduit means is formed at an angle of from 40 to 90 degrees to the longitudinal axis of the first conduit means.

13. A feeding system for connecting a humidifier to a reservoir, comprising: first elongated conduit means for feeding water from the reservoir to the humidifier; second elongated conduit means alongside the first conduit means for passing air from the humidifier to the reservoir; means for connecting an upstream end of the first and second conduit means in fluid communication to the reservoir; and an elbow connected to the first and second conduit means and having a hollow first part surrounding and spaced from the first and second conduit means, and a second hollow second part in fluid communication with the first part and extending at an angle to the longitudinal axes of the first and second conduit means, with a downstream end portion of the first and second conduit means extending through and from the elbow to a location inside the humidifier.

14. A system as claimed in Claim 13 in which the outside diameter of the first conduit means is substantially smaller than the outside diameter of the second conduit means.

15. A system as claimed in Claim 13 in which the internal diameter of the first conduit means is substantially smaller than the internal diameter of the second conduit means.

16. A system as claimed in Claim 13, 14 or 15 in which the internal diameter of the first conduit means is approximately .080 inches (2 mms), and the internal diameter of the second conduit means is approximately .260 inches (6.6 mms).

17. A system as claimed in any one of Claims 13 to 16 in which the ratio of the internal diameter of the second conduit means to the internal diameter of the first conduit means is at least 3:1.

18. A system as claimed in any one of Claims 13 to 17 in which the internal diameter of the first part of the elbow is approximately .730 inches (18.5 mms).

19. A system as claimed in any one of Claims 13 to 18 in which the ratio of the internal diameter of the first part of the elbow to the external width of the first and second conduit means is at least 1.5:1.

20. A feeding system for connecting a humidifier to a reservoir, comprising: first elongated conduit means for feeding water from the reservoir to the humidifier; second elongated conduit means alongside the first conduit means for passing air from the humidifier to the reservoir; means for connecting an upstream end of the first and second conduit means in fluid communication to the reservoir; and flanges being secured to the upstream end of the conduit means and securement means adapted to engage the said flanges and to engage a formation on the reservoir whereby the conduits are removably secured to the said reservoir.

21. A system as claimed in Claim 1, Claim 7, Claim 13 or Claim 20 substantially as specifically described herein with reference to the accompanying drawings.