Inducing hypothermia and rewarming using a helium-oxygen mixture

• US 20030131844A1
• Filed: 12/04/2002
• Published: 07/17/2003
• Est. Priority Date: 12/04/2001
• Status: Active Grant

• Current Assignee: Minnesota High Tech Resources LLC
• Original Assignee: Minnesota High Tech Resources LLC
• Inventors: Johnson, Larry D., Kumar, Matthew M.
• Granted Patent: US 6,983,749 B2
• Time in Patent Office: Days
• US Class Current: 128/200.24
• CPC Class Codes: A61K 33/00 Medicinal preparations containing inorganic active ingredients
• CPC Class Codes: A61M 16/0054 Liquid ventilation
• CPC Class Codes: A61M 16/0075 Bellows-type
• CPC Class Codes: A61M 16/0081 Bag or bellow in a bottle
• CPC Class Codes: A61M 16/0833 T- or Y-type connectors, e.g. Y-piece
• CPC Class Codes: A61M 16/1075 by influencing the temperature A61M16/1045 takes precedence
• CPC Class Codes: A61M 16/14 by mixing different fluids, one of them being in a liquid phase
• 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: A61M 19/00 Local anaesthesia syringes therefor A61M5/00; Hypothermia A61M5/42 takes precedence; cooling blood in a bypass of the arterial system A61M1/36
• CPC Class Codes: A61M 2202/0476 Oxygenated solutions
• CPC Class Codes: A61M 2230/50 Temperature
• CPC Class Codes: A61P 9/10 for treating ischaemic or atherosclerotic diseases, e.g. antianginal drugs, coronary vasodilators, drugs for myocardial infarction, retinopathy, cerebrovascula insufficiency, renal arteriosclerosis
• CPC Class Codes: Y10S 128/913 Breathable liquids

Abstract

Devices and methods to heat and cool human beings, including inducing and maintaining hypothermia in human patients. Methods include inducing hypothermia to treat ischemic events, including heart attack and stroke, to limit damage caused by the ischemic event. Methods can include: using the lungs for heat exchange; using cooled gases for ventilation; using helium in the ventilation gas mixture, using medications to control reflex heat production; and injecting a perfluorocarbon mist into the gas stream to increase the cooling rate. The high thermal conductivity and diffusivity of helium results in greater inspired gas temperature equalization toward body temperature. Due to the latent heat of vaporization, addition of even small quantity of phase-change perfluorocarbon dramatically increases the heat carrying capacity of the respiratory gases. Hypothermia may be terminated by discontinuing the medications and warming the patient using a warmed helium-oxygen mixture.

Claims

1. A method for medical treatment comprising:

selecting a human patient that has had an ischemic event or is undergoing a surgery associated with a significant probability of causing ischemia;

providing a cooled gas mixture comprising helium and oxygen and having a temperature of less than about, 10 degrees Centigrade; and

ventilating the patient using the cooled gas mixture to lower the patient'"'"'s core body temperature to reduce tissue oxygen consumption.

2. A method as in claim 1, wherein the cooled gas mixture has a temperature of less than 5 degrees Centigrade.

3. A method as in claim 1, wherein the selecting step includes selecting a patient that has had an ischemic event selected from the group consisting of heart attacks and strokes.

4. A method as in claim 1, wherein the method further comprises providing a liquid having a boiling point of less than 37 degrees Centigrade, atomizing the liquid into droplets, and wherein the ventilating step includes ventilating the patient with the gas mixture, with the gas mixture forming a substantially continuous phase and the liquid droplets being carried in the gas mixture.

5. A method as in claim 1, wherein the providing liquid provides a perfluorocarbon.

6. A method as in claim 5, wherein the providing liquid provides a perfluorocarbon having oxygen solubility sufficiently high to sustain life for at least a one hour procedure.

7. A method as in claim 4, wherein the ventilating includes injecting the atomized liquid into the gas mixture outside of the patient.

8. A method as in claim 4, wherein the ventilating includes injecting the atomized liquid into the gas mixture inside of the patient'"'"'s trachea.

9. A method as in claim 4, wherein the perfluorocarbon liquid forms a substantially continuous liquid phase having at least some of the gas mixture dissolved within.

10. A method as in claim 4, wherein the perfluorocarbon liquid forms a substantially continuous liquid phase having at least some of the gas mixture comprising bubbles entrained within.

11. A method as in claim 1, wherein the gas mixture comprises at least 50% helium by volume.

12. A method as in claim 4, wherein the perfluorocarbon includes perfluorocarbons having the formula C5F12.

13. A method as in claim 1, wherein the helium comprises at least 50 percent of the gas mixture by volume.

14. A method as in claim 1, wherein the method further comprises administering at least one drug that suppress reflex heat production by the human being body when cooling occurs.

15. A method as in claim 1, wherein drugs are administered to the patient to enhance and/or maintain hypothermia, wherein the drugs are selected from the group consisting of general anesthetics, narcotics, sedatives, morphine, Demerol, fentanyl, drugs that act on seratonin and /or dopamine receptors, neuromuscular blocking agents, curare, pancuronium, succinylcholine, clonidine, nefopam, anti-catecholamine drugs, reserpine, propranolol, and anti-thyroid agents and combinations thereof.

16. A method as in claim 1, wherein the ventilating step includes supplying the cooled gas mixture through an insulated tube to an endotracheal tube or face mask.

17. A system for inducing hypothermia in humans, the system comprising:

a first gas intake for coupling to an oxygen source;

a second gas intake for coupling to a helium source;

a mixing region coupled to the first and second gas intakes for combining the oxygen and helium to produce a gas mixture;

a cooling region in fluid communication with the mixing region for cooling the oxygen and helium; and

a gas outlet in fluid communication with the cooling region that can be used for operably coupling the cooled gas mixture to a breathing tube or endotracheal tube or face mask.

18. A system as in claim 17, wherein the cooling region is disposed to cool the helium and oxygen before mixing.

19. A system as in claim 17, wherein the cooling region is disposed to cool the helium and oxygen after mixing.

20. A system as in claim 17, wherein the system includes a recirculation loop for receiving the exhaled gases from the patient, removing or scrubbing some of the carbon dioxide from the exhaled gases, and adding the scrubbed exhaled gases to newly added oxygen and helium gases.

21. A system as in claim 17, wherein the system includes pin index coupling for coupling the first and second gas intakes specifically to helium and oxygen sources.

22. A system as in claim 17, wherein the system includes a device for injecting a perfluorocarbon into the gas mixture.

23. A system as in claim 17, wherein the cooling region has a cooling region outlet temperature, wherein the system includes a controller for controlling the cooling region output temperature responsive to a temperature measured in the patient.

24. A system as in claim 17, wherein the system includes a ventilator for providing a positive pressure gas mixture to the patient.

25. A system as in claim 22, wherein the system includes a condenser system coupled to recover the liquid exhaled from the patient.

26. A system as in claim 17, wherein the system includes tubing for conveying the oxygen, helium, and gas mixture, wherein at least some of the tubing is insulated to substantially reduce warming of the gas mixture from the room temperature.

27. A method for inducing hypothermia in a human patient, the method comprising performing partial liquid ventilation on the patent using a liquid perfluorocarbon having a temperature less than 20 degrees Centigrade and a gas comprising helium and oxygen and having a temperature of less than 20 degrees Centigrade.

28. A composition of matter comprising:

helium gas;

oxygen gas; and

a perfluourocarbon liquid having a boiling point less than 37 degrees centigrade.

29. A composition of matter as in claim 28, wherein the helium gas is present in a concentration of at least 50 volume percent.

30. A composition of matter as in claim 29, wherein the oxygen gas is present in a concentration of at least 17 volume percent.

31. A composition of matter as in claim 30, wherein the perflourocarbon is biocompatible.

32. A composition of matter as in claim 28, wherein the perflurocarbon is present as droplets in the helium and oxygen gas.

33. A composition of matter as in claim 28, wherein the perflurocarbon droplets have an average droplet diameter of less than about 10 microns.

34. A composition of matter as in claim 28, wherein the composition has a temperature of less than 10 degrees Centigrade.