GB2388550A

GB2388550A - Apparatus for breathable gas delivery

Info

Publication number: GB2388550A
Application number: GB0211236A
Authority: GB
Inventors: Silvia Beatriz Dougill; Graham Sydney Lawrence
Original assignee: BOC Group Ltd
Current assignee: BOC Group Ltd
Priority date: 2002-05-16
Filing date: 2002-05-16
Publication date: 2003-11-19
Also published as: GB0211236D0

Abstract

An apparatus for delivering to a patient a breathable gas mixture containing oxygen and at least one other gas includes a non-cryogenic air separation unit in the form of a pressure swing adsorption unit (PSA) 2. The PSA unit 2 has an inlet 4 for air and an outlet 6 for oxygen-enriched air. The apparatus also includes a source of the other gas under pressure, for example, a cylinder 10 of helium. The helium and oxygen-enriched air are typically mixed in a chamber 14 or upstream of the chamber 14. The chamber 14 communicates with a mask 18 for administering the breathable gas mixture to the patient.

Description

MEDICAL APPARATUS

The present invention relates to apparatus for delivering breathable gas mixtures to a patient.

À Oxygen or oxygen enriched air is prescribed to patients to improve oxygen delivery to vital organs. For example, oxygen is used to correct chronic hypoxaemia, to reduce transient oxygen desaturation and exercise hypcxaemia and to reduce breathlessness. Non-cryogenic air separation units or "oxygen concentrators" are known which provide oxygen enriched air up to approximately 95% by volume oxygen to patients at home or in hospital. Particular oxygen concentrators are prescribed in the case of long term oxygen therapy. The concentrators usually provide oxygen concentrations of about 95% by volume depending on the flow. Flow rates of up to 5 litres per minute and pressure of about 5psig are normally achieved.

Helium/oxygen mixtures are known to increase ventilation and increase oxygen saturation for the improvement of lung function and to reduce the sensation of breathlessness. It is an aim of the present invention to provide an apparatus for delivering a breathable gas mixture containing oxygen and at least one other gas to a patient.

Preferably, the other gas is helium or a helium/oxygen gas mixture.

According to the present invention, an apparatus for delivering a breathable gas mixture containing oxygen and at least one other gas/gas mixture to a patient comprises a non-cryogenic air separation unit including an inlet for air and an outlet for oxygen enriched air, a source of the other gas/gas mixture under pressure, means for mixing the oxygen enriched air and the other gas/gas mixture to form a breathable gas mixture and means for delivering the breathable gas mixture to the patient.

- 2 Preferably, the oxygen enriched air and the other gas/gas mixture are mixed together in a gas mixing chamber and a line from the gas mixing chamber allows for the passage of the breathable gas mixture contained within the gas mixing chamber to the patient Either an electrically operated compressor or a gas driven compressor may be provided which feeds air under pressure in to the inlet of the non-cryogenic air separation unit.

Embodiments of the invention will now be described, by way of example, reference being made to the Figures of the accompanying diagrammatic drawings in which Figures 1 to 4 are schematic diagrams illustrating various embodiments of an apparatus for delivering a breathable gas mixture containing oxygen and at least one other gas/gas mixture to a patient according to the present invention Referring first to Figure 1, an apparatus for delivering a breathable gas mixture containing oxygen and helium to a patient includes a non-cryogenic air separation unit in the form of a pressure swing adsorption (PSA) unit 2 having an inlet 4 for air and an outlet 6 for oxygen enriched air. An electrically operated compressor 8 is in communication with the inlet 4 as is a cylinder 10 of helium gas under pressure. A line 12 extends from the outlet 6 to a gas mixing chamber 14 and a further line 16 extends from the gas mixing chamber 14 to a breathing mask 18 to be worn by a patient. An oxygen monitor 20 is connected to the gas mixing chamber 14, which monitor 20 may be connected to a safety device (not shown).

In use, the compressor 8 will force air under pressure in to the inlet 4 and through the PSA unit 2 towards the outlet 6. As is well known, nitrogen in the air will be adsorbed preferentially within the PSA unit 2 and oxygen enriched air will exit the unit 2 via the outlet 6. Simultaneously, helium from the cylinder 10 will also pass through the PSA unit 2 towards the outlet 6. Both the oxygen enriched air and the

( - 3 helium will proceed along the line 12 in to the gas mixing chamber 14 where they will be thoroughly mixed. On demand by the patient the breathable gas mixture within the gas mixing chamber 14 will pass through the line 16 towards the mask 18 for delivery to the patient.

The oxygen monitor 20 will ensure that the operator of the apparatus will know precisely the percentage by volume of oxygen in the breathable gas mixture that is being delivered to the patient. If the volume of oxygen in the breathable gas mixture being delivered to the patient should fall below a preselected level, for example less than 21% by volume, then the safety device can be set to stop the delivery of the breathable gas mixture to the patient.

Referring now to Figure 2 where like reference numerals denotes like parts, the difference between the apparatus illustrated in Figure 2 and the apparatus of Figure 1 is that the cylinder 10 of helium instead of being in communication with the inlet 4 of the PSA unit 2, is instead in communication with the outlet 6 of the PSA unit 2 and flows directly in to the line 12. Thus the oxygen/helium mixture is obtained at the outlet of the PSA unit 2. This method has the advantage of minimal alteration to the PSA unit 2 to provide a selected oxygen/helium mixture.

Referring now to Figure 3 where like numerals denote like parts, a gas driven compressor 22 has been provided between the helium cylinder 10 and the inlet 4 of the PSA unit 2 in a line 24. In use, when helium under pressure leaves the cylinder 10 it will pass through the compressor 22 and draw in air such that air and helium will leave the compressor through the line 24 and in to the inlet 4 and hence through the PSA unit 2.

Some patients find electricity bills a financial burden where an electrically driven compressor is used. In this embodiment the pressure from the helium gas is used to force air in to the PSA unit 2 using the compressor 22.

( - 4 Referring now to Figure 4 where like reference numerals denote like parts the non-cryogenic air separation unit is in the form of a membrane unit 26 and as with the embodiment illustrated in Figure 3 gas under pressure from the cylinder 10 which can contain either pure helium or a mixture of helium and oxygen passes through the compressor 22 such that air passes under pressure through the line 24 to the inlet 4 of the membrane unit 26. A line 26 from the compressor 22 connects with the line 12 to allow the flow of the helium or oxygen/helium mixture in to the line 12.

Oxygen enriched air and the helium or oxygen/helium mixture then passes through the line 12 in to the gas mixing chamber 14 as described with respect to the previous embodiments. All the above described embodiments enable a breathable gas mixture of oxygen and at least one other gas to be delivered in a range of compositions that can be selected to suit a patient's oxygen requirements. Although non-cryogenic air separation units have been described including a PSA unit and a membrane unit, clearly other non-cryogenic air separation units could be used, for example, a temperature swing adsorption unit.

Again, although reference has been made to helium contained in a cylinder under pressure, gases other than helium or gas mixtures are clearly contemplated.

Using the apparatus described with respect to the embodiments illustrated by Figures 1 to 4, a breathable gas mixture at higher pressure than simply that obtained through a concentrator can be produced to drive a nebuliser if necessary.

Although reference has been made to a mask 18 for use by a patient clearly the gas mixture passing through the line 16 could be delivered to the patient, for example, via a nasal cannula.

Although in all the embodiments reference has been made to the gas mixing chamber 14 it will be clear that gas mixing can take place in the line 12 and/or line 16 before reaching the mask 18 or at the mask 18 itself.

Claims

- 5 CLAIMS

1. An apparatus for delivering a breathable gas mixture containing oxygen and at least one other gas/gas mixture to a patient comprising a noncryogenic air separation unit including an inlet for air and an outlet for oxygen enriched air, a source of the other gas/gas mixture under pressure, means for mixing the oxygen enriched air and the other gas/gas mixture to form a breathable gas mixture and means for delivering the breathable gas mixture to the patient.

2. An apparatus as claimed in Claim 1 in which the oxygen enriched air and the

other gas/gas mixture are mixed together in a gas mixing chamber and a line from the gas mixing chamber allows for the passage of the breathable gas mixture contained within the gas mixing chamber to the patient.

3. An apparatus as claimed in Claim 1 or Claim 2, in which an electrically operated compressor feeds air under pressure in to the inlet of the non-cryogenic air separation unit.

4. An apparatus as claimed in Claim 1 or Claim 2, in which a gas driven compressor feeds air under pressure in to the inlet of the non-cryogenic air separation unit.

5. An apparatus as claimed in any one of Claims 1 to 4 in which the source of the other gas/gas mixture is a cylinder and a line connects the interior of the cylinder to the inlet of the non-cryogenic air separation unit.

6. An apparatus as claimed in any one of Claims 2 to 5, in which the source of the other gas/gas mixture is a cylinder and a line connects the interior of the cylinder directly to the gas mixing chamber.

- 6

7. An apparatus as claimed in any one of Claims 1 to 6 in which the non-cryogenic air separation unit is a pressure swing adsorption unit.

8. An apparatus as claimed in any one of Claims 1 to 6 in which the noncryogenic air separation unit is a temperature swing adsorption unit.

9. An apparatus as claimed in any one of claims 1 to 6 in which the noncryogenic air separation unit is a membrane unit.

10. An apparatus as claimed in any one of Claims 2 to 9, in which an oxygen monitor is provided for monitoring the percentage by volume of oxygen in the gas mixing chamber.

11. An apparatus as claimed in Claim 10, in which the oxygen monitor is connected to a safety device capable of stopping delivery of the breathable gas mixture to the patient when the percentage of oxygen by volume in the = breathable gas mixture falls below 21%.

12. An apparatus as claimed in any one of Claims 2 to 11 in which the line from the gas mixing chamber is connected to a mask for use by a patient.

13. An apparatus as claimed in any one of Claims 2 to 11 in which the line from the gas mixing chamber is connected to a nasal cannula for use by a patient.

14. An apparatus for delivering a breathable gas mixture containing oxygen and at least one other gas to a patient constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the Figures of the accompanying drawings.