Forced Air Warming Blanket Flashcards
What major organ produces the greatest amount of
heat as a byproduct of its metabolic function?
All of the major organs produce a significant amount of heat, but
the brain produces the most.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1505
What are the three components to a forced air
warmer?
An inflatable blanket, an electrical control unit, and a hose
Sandberg WS, Urman RD, Ehrenfield JM. The MGH Textbook
of Anesthetic Equipment. Philadelphia, PA: Elsevier Saunders;
2011: 265.
Why should heavy blankets not be placed over a
forced-air blanket?
Heavy blankets force all of the warmed air directly to the
patient’s skin, increasing the risk for burns.
Sandberg WS, Urman RD, Ehrenfield JM. The MGH Textbook
of Anesthetic Equipment. Philadelphia, PA: Elsevier Saunders;
2011: 301.
Why should forced air warmers not be applied to
ischemic areas or areas with poor perfusion?
There is a risk for burns
Sandberg WS, Urman RD, Ehrenfield JM. The MGH Textbook
of Anesthetic Equipment. Philadelphia, PA: Elsevier Saunders;
2011: 265.
What is the definition of hypothermia?
Hypothermia is said to exist when the core body temperature is
less than 96.8 degrees F or 36 degrees Celsius.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1505.
What method of heat transfer do forced air warmers
use?
Convection
Sandberg WS, Urman RD, Ehrenfield JM. The MGH Textbook
of Anesthetic Equipment. Philadelphia, PA: Elsevier Saunders;
2011: 265.
What is the central ‘controller’ for body temperature?
The anterior hypothalamus
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1506.
What is does the term ‘interthreshold range’ mean,
and how does anesthesia play a role in it?
The interthreshold range is the range of body temperature at
which the compensatory responses for cold are not activated
and the compensatory mechanisms for heat are not activated
either. In a normal, healthy adult, this range is about 0.4
degrees Celsius. Anesthesia widens this range to about 7.2
degrees F or 4 degrees C. This means that ambient
temperature and heat loss mechanisms play a larger part in
determining core body temperature.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1507
The loss of core temperature that occurs under
anesthesia follows a predictable pattern. Describe
this pattern of heat loss.
There is an initial rapid decrease in core temperature by about
0.9-2.7 degrees F (0.5-1.5 degrees Celsius) during the first hour
of anesthesia. A gradual decline occurs that lasts about 2-3
hours. A plateau occurs at about 3-4 hours where heat loss
and heat production are equal and the temperature no longer
changes.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1507.
What is the first compensatory response to heat loss?
Cutaneous vasoconstriction, which can decrease heat loss by
25-50%
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1506.
When does the body initiate shivering as a means of
increasing the core body temperature?
Shivering is only initiated after cutaneous vasoconstriction and
nonshivering thermogenesis fail to maintain core body
temperature.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1506.
What is the principal disadvantage of shivering?
Shivering increases total body oxygen consumption by 2-3
times. Shivering also increases intraocular and intracranial
pressure.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1506
What is nonshivering thermogenesis?
Nonshivering thermogenesis is a norepinephrine-mediated
mechanism of heat production that involves uncoupling of
oxidative phosphorylation within the mitochondria-rich brown fat
cells found over the neck, back, viscera, and great vessels.
Nonshivering thermogenesis occurs in premature infants and
full-term newborns, but does not occur in adults.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1507.
What composes the core compartment versus the
peripheral compartment?
The core compartment is considered to be composed of the
trunk, the head, and the major organs. The peripheral
compartment consists of the skin, the superficial tissues of the
trunk, the arms, and the legs.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1505-
1506.
According to U.S. standards, what is the AVERAGE
contact surface temperature a forced-air device
cannot exceed?
46 degrees Celsius
Dorsch JA, Dorsch SE. Understanding Anesthesia Equipment.
5th ed. Philadelphia, PA: Lippincott Williams and Wilkins, 2008:
887.
