Pediatric emergency medicine trisk 1956 1956
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baths is also possible but complicates monitoring or response to arrhythmias.
These methods, however, cause early warming of the skin and extremities with
peripheral vasodilation and shunting of cold, acidemic blood to the core. This
causes the well-known phenomenon of “afterdrop” of core temperature. Severe
hypotension may also occur in chronic cases as vasodilation increases the
effective vascular space. External rewarming techniques limited to the head and
trunk may minimize vasodilation and afterdrop. In acute hypothermia, active
external rewarming is appropriate, but there is some evidence that in chronic
cases (more than 24 hours), mortality is higher if active external rewarming is
used instead of simple passive techniques.
Core rewarming techniques are almost certainly more rapid and less likely to
be associated with afterdrop, dangerous arrhythmias, or significant hypotension.
These methods are especially valuable in the setting of severe chronic
hypothermia (temperature less than 32°C [89.6°F]), where fluid shifts are most
likely to occur. A nonshivering model of severe hypothermia indicated that
inhalation rewarming offered no rewarming advantage, whereas forced air
warming (approximately 200 W) allowed a 6- to 10-fold increase in rewarming
rate over controls. At the same time, peritoneal dialysis with dialysate warmed to
43°C (109.4°F) is effective and requires only equipment routinely available in
most hospitals. Gastric or colonic irrigation has also been advocated, but
placement of the intragastric balloon may precipitate dysrhythmias.
Hemodialysis, extracorporeal blood rewarming, and mediastinal irrigation are
effective but require mobilization of sophisticated equipment and personnel. New
endovascular warming catheters, introduced after cannulization of the femoral
vein and advancement to the inferior vena cava, use closed-loop circuitry to
maintain the patient’s temperature.
Indications for Admission and Discharge
In patients with mild temperature depression (greater than 32°C [89.6°F]),
external rewarming techniques and supportive care based on vital signs, ABGs,
and metabolic parameters such as glucose and calcium levels, should result in
prompt recovery. Patients with mild hypothermia due to environmental exposure
who improve with passive rewarming may be discharged after observation in the
ED. However, it should be noted that other causes of hypothermia should be ruled
out prior to discharge.
Children who present with a temperature less than 32°C (89.6°F), and
especially those in whom hypothermia developed over 24 hours or more, require
meticulous attention to continuously changing vital signs and metabolic needs.
More elaborate core rewarming techniques are appropriate.
