Respiratory system for inducing therapeutic hypothermia
The present invention provides a method and apparatus for controlling a patient's body temperature and in particular for inducing therapeutic hypothermia. Various embodiments of the system are described. The system includes: a source of breathing gas, which may be in the form of a compressed breathing gas mixture; a heat exchanger or other heating and/or cooling device; and a breathing interface, such as a breathing mask or tracheal tube. Optionally, the system may include additional features, such as a mechanical respirator, a nebulizer for introducing medication into the breathing gas, a body temperature probe and a feedback controller. The system can use air or a specialized breathing gas mixture, such as He/O.sub.2 or SF/O.sub.2 to increase the heat transfer rate. In addition, the system may include an ice particle generator for introducing fine ice particles into the flow of breathing gas to further increase the heat transfer rate.
1. A method for inducing therapeutic hypothermia in a patient, comprising:
selecting a patient in need of therapeutic hypothermia;
introducing fine ice particles into a flow of breathing gas under controlled conditions selected to produce a breathing gas which induces hypothermia when the gas is breathed by the patient; and
delivering the flow of breathing gas containing the fine ice particles to the patient, wherein therapeutic hypothermia is induced in the patient.
2. The method of claim 1 , further comprising cooling the flow of breathing gas.
3. The method of claim 1 , wherein the fine ice particles are introduced into the flow of breathing gas by cooling the flow of breathing gas to a temperature below freezing and introducing fine droplets of water into the flow of breathing gas.
4. The method of claim 1 , wherein the fine ice particles are introduced into the flow of breathing gas by cooling the flow of breathing gas to a temperature below freezing and introducing fine droplets of saline solution into the flow of breathing gas.
5. The method of claim 1 , further comprising measuring a body temperature of the patient and controlling a delivery rate of the fine ice particles to the patient based on the measured body temperature of the patient.
6. The method of claim 1 , wherein the breathing gas comprises a mixture containing oxygen and helium.
7. The method of claim 1 , wherein the breathing gas comprises a mixture containing oxygen and sulfur hexafluoride.
8. The method of claim 1 , further comprising administering an antishivering agent to the patient.
9. The method of claim 1 , further comprising rewarming the patient by delivering a flow of heated breathing gas to the patient.