d. Induction of anesthesia inhibits shivering, produces vasodilation and
redistributes blood flow from the warm core to the periphery.
Normally body heat is unevenly distributed, the temperature of core
tissues being 2° to 4°C greater than skin temperature. Redistribution
leads to a 0.5° to 1.5°C decrease in core temperature. Radiant heat loss
accounts for about 60% of total heat loss in the perioperative period.
2. Which factor does not contribute to
heat loss in the perioperative period?
a. the use of inhalational agents
b. anesthetically induced increases in the thermoregulatory threshold
c. use of large amounts of intravenous fluids
d. average ambient OR temperatures
b. Dry anesthetic gases, large volumes of cold IV fluids and the usually
cold ambient OR temperatures will all contribute to increased heat
loss in the perioperative period. Anesthetic medications, however, will
reduce, not increase, the temperature at which the hypothalamus will
initiate normal thermoregulatory mechanisms. Under normal condi-
tions the hypothalamus will initiate thermogenic responses when core
temperatures drop as little as 0.1° below 37°C. Most anesthetics can
lower this normal threshold by as much as 4°C (20 times lower than
the normal threshold trigger).
3. The anesthetic that affects thermoregulation the least is __________ .
a. Versed
b. fentanyl
c. propofol
d. sevoflurane
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