Carbon dioxide absorbent in anaesthesiology

• US 6,228,150 B1
• Filed: 09/03/1999
• Issued: 05/08/2001
• Est. Priority Date: 11/25/1996
• Status: Expired due to Term

• Current Assignee: Armstrong Medical Limited (Hygion Healthcare BV)
• Original Assignee: Armstrong Medical Limited (Hygion Healthcare BV)
• Inventors: Armstrong, John Raymond, Murray, James
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US09/308,774
• Time in Patent Office: 613 Days
• Field of Search: 95/139, 95/900, 423/230, 423/234, 96/108, 96/147, 55/512, 55/516, 55/DIG. 5
• US Class Current: 95/139
• CPC Class Codes: A61M 16/22 Carbon dioxide-absorbing devices ; Other means for removing carbon dioxidecartridges with absorbing substances for respiratory apparatus A62B19/00
• CPC Class Codes: B01D 2251/404 of calcium
• CPC Class Codes: B01D 2251/604 Hydroxides
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01J 20/0248 Compounds of B, Al, Ga, In, Tl B01J20/08 takes precedence
• CPC Class Codes: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/045 containing sulfur, e.g. sulfates, thiosulfates, gypsum
• CPC Class Codes: B01J 20/046 containing halogens, e.g. halides
• CPC Class Codes: B01J 20/22 comprising organic material
• CPC Class Codes: B01J 20/262 obtained otherwise than by reactions only involving carbon to carbon unsaturated bonds, e.g. obtained by polycondensation macromolecular compounds obtained otherwise than by reactions only involving unsaturated carbon-to-carbon bonds per se C08G
• CPC Class Codes: B01J 20/3007 Moulding, shaping or extruding
• CPC Class Codes: B01J 2220/42 Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: B01J 2220/46 Materials comprising a mixture of inorganic and organic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y10S 95/90 Solid sorbent

Abstract

The invention concerns a carbon dioxide absorbent for use in anaesthesiology, in which the absorbent comprises at least one pharmaceutically acceptable hydroxide essentially free of sodium and/or potassium hydroxide and a carbon dioxide absorbingly effective amount of a compatible humectant. Calcium hydroxide is the preferred hydroxide. The humectant may be of inorganic or organic origin. The carbon dioxide absorbent of the invention may, additionally, include an effective amount of a setting agent, preferably calcium sulphate hemihydrate and/or a compatible agent for internal generation of hydrogen, preferably aluminium metal powder. The carbon dioxide absorbent of the invention is chemically inert to sevoflurane, as well as to the anaesthetics enflurane, isoflurane and desflurane.

Claims

1. A method of absorbing carbon dioxide in low flow or closed circuit anaesthesiology, said method comprising the step of contacting a gas stream containing carbon dioxide with an absorbent, said absorbent comprising calcium hydroxide, and a hygroscopic or deliquescent inorganic humectant or a mixture thereof, wherein the calcium hydroxide is essentially free of sodium and potassium hydroxide.

2. The method according to claim 1, wherein said inorganic humectant is a hygroscopic or deliquescent hydrate.

3. The method according to claim 1, wherein said inorganic humectant is selected from the group consisting of calcium chloride hexahydrate, magnesium chloride hexahydrate, or a mixture thereof.

4. The method according to claim 3, wherein said inorganic humectant is calcium chloride hexahydrate, which is present in an amount sufficient to yield, based on molecular weight, from 7.5% to 20% (w/w) of water.

5. The method according to claim 1, wherein said absorbent further comprises an organic humectant.

6. The method according to claim 5, wherein said organic humectant is a dihydric or polyhydric substance.

7. The method according to claim 5, wherein said organic humectant is selected from the group consisting of glycerol, polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 1540, propylene glycol, hexan-1,2,6-triol, or a mixture thereof.

8. The method according to claim 5, wherein said organic humectant is glycerol, which is present at 2.5% to 25% (v/w).

9. The method according to claim 5, wherein the water content of the absorbent, as measured by Karl Fischer titration, is from 17.5% to 30%.

10. The method according to claim 5, wherein said absorbent further comprises an effective amount of a compatible setting agent.

11. The method according to claim 10, wherein the setting agent is calcium sulphate hemihydrate.

12. The method according to claim 10, wherein the setting agent is from 4% to 5.5% (w/w) calcium sulphate hemihydrate.

13. The method according to claim 10, wherein said absorbent further comprises a compatible agent for internal generation of hydrogen.

14. The method according to claim 13, wherein said compatible agent is aluminum metal powder.

15. The method according to claim 14, wherein the aluminum metal powder is present at 0.5 to 1% (w/w).

16. The method according to claim 5, wherein said absorbent further comprises a compatible agent for internal generation of hydrogen.

17. The method according to claim 1, wherein the water content of the absorbent, as measured by Karl Fischer titration, is from 17.5% to 30%.

18. The method according to claim 1, wherein said absorbent further comprises an effective amount of a compatible setting agent.

19. The method according to claim 1, wherein said absorbent further comprises a compatible agent for internal generation of hydrogen.

20. A carbon dioxide absorbent for use in low flow or closed circuit anaesthesiology, the absorbent comprising calcium hydroxide, and a hygroscopic or deliquescent inorganic humectant or a mixture thereof, wherein the calcium hydroxide is essentially free of sodium and potassium hydroxide.

21. The absorbent according to claim 20, wherein said inorganic humectant is a hygroscopic or deliquescent hydrate.

22. The absorbent according to claim 20, wherein said inorganic humectant is selected from the group consisting of calcium chloride hexahydrate, magnesium chloride hexahydrate, or a mixture thereof.

23. The absorbent according to claim 22, wherein said inorganic humectant is calcium chloride hexahydrate, which is present in an amount sufficient to yield, based on molecular weight, from 7.5% to 20% (w/w) of water.

24. The absorbent according to claim 20, further comprising an organic humectant.

25. The absorbent according to claim 24, wherein said organic humectant is a dihydric or polyhydric substance.

26. The absorbent according to claim 24, wherein said organic humectant is selected from the group consisting of glycerol, polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 1540, propylene glycol, hexan-1,2,6-triol, or a mixture thereof.

27. The absorbent according to claim 24, wherein said organic humectant is glycerol, which is present at 2.5% to 25% (v/w).

28. The absorbent according to claim 24, wherein the water content of the absorbent, as measured by Karl Fischer titration, is from 17.5 to 30%.

29. The absorbent according to claim 24, further comprising an effective amount of a compatible setting agent.

30. The absorbent according to claim 29, wherein the setting agent is calcium sulphate hemihydrate.

31. The absorbent according to claim 29, wherein the setting agent is from 4% to 5.5% (w/w) calcium sulphate hemihydrate.

32. The absorbent according to claim 29, further comprising a compatible agent for internal generation of hydrogen.

33. The absorbent according to claim 32, wherein said compatible agent is aluminum metal powder.

34. The absorbent according to claim 33, wherein the aluminum metal powder is present at 0.5% to 1% (w/w).

35. The absorbent according to claim 24, further comprising a compatible agent for internal generation of hydrogen.

36. The absorbent according to claim 20, wherein the water content of the absorbent, as measured by Karl Fischer titration, is from 17.5% to 30%.

37. The absorbent according to claim 20, further comprising an effective amount of a compatible setting agent.

38. The absorbent according to claim 20, further comprising a compatible agent for internal generation of hydrogen.