What is the initial approach to treating chronic hypothermia?

Initial Approach to Treating Chronic Hypothermia

For chronic hypothermia, treatment should begin with immediate protection from further heat loss, removal of wet clothing, and implementation of passive rewarming techniques, followed by active rewarming methods based on the severity of hypothermia. 1, 2

Classification of Hypothermia

Hypothermia is classified based on core body temperature:

• Cold stress: 35-37°C - Alert, possibly shivering 1
• Mild hypothermia: 32-35°C - Altered level of responsiveness, shivering 1
• Moderate hypothermia: 28-32°C - Decreased level of responsiveness, with or without shivering 1
• Severe hypothermia: <28°C - Unresponsive, may appear lifeless 1
• Profound hypothermia: <24°C - Cessation of shivering, slow heart rate and breathing, high risk for cardiac arrest 1

Initial Management Steps

1. Protect from further heat loss:

   • Move patient to a warm environment 1
   • Remove wet clothing immediately 1, 2
   • Cover with dry insulating layers 1
   • Shield from wind using plastic or foil layer 1
   • Insulate from the ground 1
   • Cover head and neck 1

2. Assess severity based on core temperature and clinical presentation:

   • Note that clinical presentation may not always match the expected findings for a given temperature, as demonstrated in rare cases where patients with severe hypothermia remain alert 3
   • Always base treatment decisions on core temperature measurement when available 3

Treatment Algorithm Based on Severity

For Mild Hypothermia (32-35°C)

• Allow passive rewarming with blankets 1, 2
• Increase environmental temperature 2
• Provide high-calorie foods or drinks if patient is alert and can safely consume 1
• Monitor for signs of deterioration 1

For Moderate Hypothermia (28-32°C)

• Continue all measures for mild hypothermia 1, 2
• Implement active external rewarming methods:
  • Heating pads 2
  • Forced warm air blankets 2, 4
  • Chemical heat blankets (follow manufacturer's instructions) 1
  • Place insulation between heat source and skin to prevent burns 1
  • Monitor frequently for burns and pressure injuries 1
• Administer warmed intravenous fluids 1, 2
• Provide humidified, warmed oxygen 1

For Severe/Profound Hypothermia (<28°C)

• Continue all measures for moderate hypothermia 1, 2
• Activate emergency response system immediately 1
• Consider active core rewarming methods:
  • Warmed IV or intraosseous fluids 1
  • Warm humidified oxygen 1
  • Consider peritoneal lavage with warmed fluids 2, 5
  • For extreme cases, consider cardiopulmonary bypass or extracorporeal blood warming 1, 5
• Handle patient gently to avoid triggering arrhythmias 1
• Transport to a facility capable of aggressive rewarming 1

Special Considerations

• If the patient cannot be immediately moved to a warm environment, use the hypothermia wrap technique with chemical heat blankets, plastic/foil layers, and insulative blankets 1
• Body-to-body rewarming is not recommended over other active rewarming techniques 1
• Target rewarming to a minimum core temperature of 36°C before transferring between units 2
• Cease rewarming after reaching 37°C as higher temperatures are associated with poor outcomes 2, 6
• Monitor for complications during rewarming:
  • Cardiac arrhythmias 1, 3
  • Rhabdomyolysis 3
  • Coagulopathy 6

Common Pitfalls and Caveats

• Hypothermia is often overlooked during initial resuscitation 2, 6
• Do not delay urgent procedures such as airway management and vascular access due to concerns about cardiac irritability 1
• Avoid active rewarming if there is any chance that the affected area might refreeze 1
• Burns can occur from improper use of active external rewarming devices 1
• Patients with decreased responsiveness, confusion, mumbling speech, pallor, cyanosis, or frozen skin require immediate activation of emergency services 1
• The clinical presentation may not always match the severity based on temperature measurement, so always use core temperature to guide treatment when available 3