Pediatric emergency medicine trisk 488

GI motility decreases at less than 34°C (93.2°F). The liver’s capacity for
detoxification or conjugation of drugs and products of metabolism is poor. Insulin
release abates, and serum glucose rises. Frank pancreatic necrosis may also occur,
producing clinical evidence of pancreatitis.

Clinical Recognition
Elevated body temperature is a routine concern for most physicians, especially
pediatricians. However, hypothermia is often overlooked. Reduced body
temperature may be a consequence or cause of many disorders but is diagnosed
only if healthcare providers maintain a high index of suspicion. Special
thermometers may be required to detect hypothermia.

Triage Considerations
A history of sudden immersion in icy water or prolonged exposure to low
environmental temperatures provides the obvious clue, but significantly low core
temperatures may occur under much less suggestive circumstances. Examples
include trauma victims found unconscious or immobile on a wet, windy, summer
day; infants who are from inadequately heated homes or who are left exposed
during prolonged medical evaluation; adolescents with anorexia nervosa; and
patients with sepsis or burns. Severe hypothermia, coma, and cardiac arrest may
present as the sudden infant death syndrome.
Hypothermia may go undetected if the patient’s temperature falls below the
lower limit of the thermometer in use or if a manual thermometer is not shaken
down adequately. Low-recording thermometers should be available in EDs and
ICUs. This diagnosis should be kept in mind for any patient with a suggestive
history or coma of uncertain cause.

Initial Assessment
Physical examination reveals a pale or cyanotic patient. At mild levels of
hypothermia, mental status may be normal, but CNS function is progressively
impaired with falling temperature until frank coma occurs at approximately 27°C

(80.6°F). BP also falls steadily at less than 33°C (91.4°F) and may be
undetectable. Heart rate slows gradually unless atrial or ventricular fibrillation
occurs. Intense peripheral vasoconstriction and bradycardia may render the pulse
unapparent or absent. At less than 32°C (89.6°F), shivering ceases, but muscle
rigidity may mimic rigor mortis. Pupils may be dilated and may not react. Deep
tendon reflexes are depressed or absent. Evidence of head trauma or other injury,
drug ingestion, and frostbite should be sought ( Figs. 90.6 and 90.7 ).


FIGURE 90.6 Frostbite of toes. Note the line of demarcation and ulcerative lesion.

Severe hypothermia mimics death. However, the significant decrease in oxygen
consumption may allow life to be sustained for long periods, even after cessation
of cardiac function. Signs usually associated with certain death (i.e., dilated
pupils or rigor mortis) have little prognostic value. If the patient’s history
suggests that hypothermia is the primary event and not a consequence of death,
resuscitation and active rewarming should be attempted, and death should be
redefined as failure to revive with rewarming.
Initial laboratory tests should include CBC, platelet count, clotting studies,
electrolytes, BUN and creatinine, glucose, serum amylase/lipase, and ABGs
corrected for temperature ( Table 90.6 ). Urine should be sent for drug screening.


FIGURE 90.7 Swollen fingers of a child with cold exposure.

TABLE 90.6
EFFECT OF BODY TEMPERATURE ON ARTERIAL BLOOD GASES
MEASURED AT 37°C (98.6°F)

pH

Paco2 (mm Hg)

For each elevation of 1
°C
−0.015
+4.4%

For each depression of 1
°C
+0.015
−4.4%

Pao2 (mm Hg)

+7.2%

−7.2%

Management and Diagnostic Studies
Therapy for hypothermia can be divided into two parts: general supportive
measures and specific rewarming techniques ( Table 90.7 ). Once hypothermia is
diagnosed, temperature must be monitored continuously as treatment progresses.
Defibrillation is less effective when body temperature is below 30°C (86°F), and


pacing is generally ineffective. Several case reports suggest that the use of
vasopressors and/or defibrillation may sometimes be effective in hypothermic
patients, although the effectiveness of antiarrhythmics is less clear. Pending
further research, it is recommended administering vasopressors and attempting
defibrillation as indicated, while aggressively rewarming the patient.