Method and apparatus for controlling a patient's body temperature by in situ blood temperature modification

Abstract

The present invention provides a method and apparatus for controlling the internal body temperature of a patient. According to the present invention, a catheter is inserted through an incision into a large blood vessel of a patient. By selectively heating or cooling a portion of the catheter lying within the blood vessel, heat may be transferred to or from blood flowing within the vessel and the patient's body temperature may thereby be increased or decreased as desired. The invention will find use in treating undesirable conditions of hypothermia and hyperthermia, or for inducing a condition of artificial hypothermia when desired. The method and system further provide for the cooling of initially hypothermic patients whose blood or body temperature has been warmed above the desired target level and the warming of initially hyperthermic patients whose blood or body temperature has been cooled below the desired target temperature.

Description

[0001] The following application is a continuation-in-part of U.S. Pat. No. 5,486,208, dated Jan. 23, 1996 which was a continuation of application Ser. No. 08 / 015,774 filed Feb. 10, 1993, now abandoned, the full disclosures of which is incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to the selective modification and control of a patient's body temperature. More particularly, the present invention provides methods and apparatus for treating hypothermia or hyperthermia by inserting a catheter into a blood vessel of the patient and selectively transferring heat to or from blood flowing through the vessel. [0004] 2. Description of the Background Art [0005] Under ordinary circumstances the thermoregulatory system of the human body maintains a near constant temperature of about 37° C. (98.6° F.). Heat lost to the environment is precisely balanced by heat produced within the body. [0006] Hypothermi...

AI Technical Summary

Problems solved by technology

Accidental hypothermia results when heat loss to the environment exceeds the body's ability to produce heat internally.

In many cases, thermoregulation and heat production are normal but the patient becomes hypothermic due to overwhelming environmental cold stress.

Hypothermia of either type is a dangerous condition which can have serious medical consequences.

In particular, hypothermia interferes with the ability of the heart to pump blood.

Hypothermia may be fatal for this reason alone.

Additionally, low body temperature seriously interferes with the enzymatic reactions necessary for blood clotting.

This sometimes results in bleeding that is very difficult to control, even when normal clotting factor levels are present.

These effects and other adverse consequences of hypothermia lead to drastically increased mortality rates both among victims of trauma and in patients undergoing surgery.

While the direct heating of patient blood can be highly effective, even in treating severe and profound cases of hypothermia, it has been observed by the inventor herein that the excess transfer of heat can cause the patient's temperature to rise above normal body temperature, resulting in hyperthermia.

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