Temperature Regulation During Anesthesia: Anesthetic-Associated Hypothermia and Hyperthermia

Temperature Regulation During Anesthesia

Anesthetic-Associated Hypothermia and Hyperthermia


Thermoregulation is a complex function of both central and peripheral mechanisms and is easily influenced by environmental and therapeutic manipulations. Abnormal body temperature in conscious animals is an indicator or a cause of metabolic dysfunction. Abnormal body temperature in anesthetized animals is a direct consequence of anesthetic–drug-related effects, environmental factors, and the temperature, volume, and rate of intravenous (IV) fluid administration.

II Thermoregulatory mechanisms

Cold and warm sensors are located in or beneath epidermal skin

Temperature signals are transmitted through A-δ and C-fibers in peripheral nerves: cold signaling is through A-δ fibers, warm signaling is through C-fibers

Thermal afferent nerves transmit information to the lateral spinothalamic tract

Central regulation is in the hypothalamus

The initial response of the body to temperature variation occurs in blood vessels and is regulated by α1– and α2-receptors; α2-receptors are important regulators of arterial-venous shunt vessels in peripheral tissues

III Heat loss mechanisms (Fig. 17-1)



Convection (facilitated conduction)


IV Hypothermia

Can be considered any temperature below a core body temperature of 37.8° C (100° F)

Rate of heat loss is related to species, animal’s weight, animal’s current temperature, and animal’s percentage of body fat

1. Hypothermia is common in small animals due to their increased body surface area compared with their smaller body mass (Fig. 17-2)

2. Increased body fat is associated with a decreased rate of heat loss (Fig. 17-3)

3. Three phases are typically associated with intraoperative hypothermia (Fig. 17-4)

Three categories of hypothermia have been defined (Table 17-1)

Sep 6, 2016 | Posted by in SUGERY, ORTHOPEDICS & ANESTHESIA | Comments Off on Temperature Regulation During Anesthesia: Anesthetic-Associated Hypothermia and Hyperthermia

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