[Frontiers in Bioscience S2, 1145-1154, June 1, 2010]

The Effect of anesthesia on body temperature control

Rainer Lenhardt

Department of Anesthesiology & Perioperative Medicine, University of Louisville, Louisville, KY

TABLE OF CONTENTS

1. Abstract
2. Introduction
2. Introduction
2.1. History
3. Normal thermoregulation
3.1. Autonomic thermoregulatory defenses
3.1.1. Sweating and vasodilatation
3.1.2. Vasoconstriction
3.1.3. Shivering
3.2. Characteristics of autonomic thermoregulatory defense mechanisms
4. Anesthesia and thermoregulation
4.1. General anesthesia
4.1.1. Heat balance during general anesthesia
4.2. Neuraxial anesthesia
4.2.1. Heat balance during regional anesthesia
4.3. Consequences of inadvertent hypothermia during anesthesia
4.4. Avoiding hypothermia during anesthesia
4.5. Anesthesia and fever
4.5.1. Causes of perioperative fever
4.5.2. Intraoperative fever
4.5.3. Postoperative fever
5. References

1. ABSTRACT

The human thermoregulatory system usually maintains core body temperature near 37 degrees C. This homeostasis is accomplished by thermoregulatory defense mechanisms such as vasoconstriction and shivering or sweating and vasodilatation. Thermoregulation is impaired during general anesthesia. Suppression of thermoregulatory defense mechanisms during general anesthesia is dose dependant and mostly results in perioperative hypothermia. Several adverse effects of hypothermia have been identified, including an increase in postoperative wound infection, perioperative coagulopathy and an increase of postoperative morbid cardiac events. Perioperative hypothermia can be avoided by warming patients actively during general anesthesia. Fever is a controlled increase of core body temperature. Various causes of perioperative fever are given. Fever is usually attenuated by general anesthesia. Typically, patients develop a fever of greater magnitude in the postoperative phase. Postoperative fever is fairly common. The incidence of fever varies with type and duration of surgery, patient's age, surgical site and preoperative inflammation.