Evaluation and Treatment of Hypothermia, Colin K. Grissom, M.D.
page 6
Management and Treatment
Prevent Heat Losses
Prevention of further heat losses is key to the care of all hypothermic patients.
The patient should be gently removed from the cold environment, disrobed of wet
clothing, kept from the chilling effects of wind exposure, and insulated from the ground
or other cold conductive materials. The patient may be placed in a sleeping bag or
wrapped with dry wool blankets, or both. Because the head is a source of great heat loss
it should be covered leaving only the face exposed. The layering of several wool blankets
around the patient provides additional insulation through the formation of air pockets
between blankets. Heat packs or hot water bottles may be placed between the layers of
wool blankets or in stockings or mittens, but not directly on the patient. A wool stocking
cap assists in preventing heat losses from the head. An insulating pad should be placed
between the patient and the ground. The entire insulation system should be wrapped in a
vapor barrier, which may be accomplished with a large piece of heavy plastic. If wet
clothing cannot be removed safely, place the vapor barrier between the clothing and
insulation. If the patient is dry, the barrier could be placed outside the insulation.
Although a patient may be hypothermic, a complete patient assessment should
always be performed to determine other injuries. During the examination every attempt
should be made to limit the surface area exposed to prevent further heat loss. Trauma
patients should have injuries stabilized and spinal column immobilization applied if
indicated.
Measurement of Core Body Temperature
Important in the diagnosis of hypothermia is knowledge of the body's core
temperature. Knowing the core temperature allows hypothermia to be classified as mild
(35 - 32°C), moderate (32 - 28°C), or severe (below 28°C). The aggressiveness of the
treatment depends upon the severity of the hypothermia and the presence or absence of
cardiac arrest. Multiple routes are available for assessment of "core" temperature, each
with certain advantages and disadvantages. Whatever the route chosen to measure "core"
temperature it is important to recognize that in non-steady state conditions of cooling or
rewarming, temperature gradients exist in the body and differences in measurements are
observed at different sites. Different methods of measuring core body temperature
include:
1.
Pulmonary artery temperature. Probably the most accurate is measurement of the
mixed venous blood in the pulmonary artery or right atrium, however, placement of
catheters in these locations in moderate or severely hypothermic patients may
precipitate arrhythmias.
2.
Esophageal temperature measured with a catheter inserted to the level of the heart
may be the best surrogate for pulmonary artery temperature because of its proximity
to the heart.
3.
Rectal temperature is probably the most convenient if a temperature probe is inserted
to 15 cm, but may be influenced by cold feces or frozen extremities, and rectal
temperature lags behind pulmonary artery temperature during rewarming.
4.
Tympanic temperature theoretically approximates hypothalamic temperature and can
be accurately measured with thermometers in contact with the tympanic membrane.
