What is the appropriate management of hypothermia, including mild, moderate, and severe cases?

Management of Hypothermia

For hypothermia management, immediately remove the patient from cold exposure, remove wet clothing, and initiate rewarming based on severity: passive rewarming for mild cases (32-35°C), active external rewarming for moderate cases (28-32°C), and active core rewarming with emergency activation for severe cases (<28°C). 1

Initial Assessment and Universal Interventions

All hypothermic patients require immediate protection from further heat loss regardless of severity 1:

• Move the patient from cold environment to warm shelter immediately 1
• Remove all wet clothing without delay 1, 2
• Insulate from the ground and cover head and neck 1
• Shield from wind using plastic or foil layer plus dry insulating layer 1
• Handle gently to avoid triggering cardiac arrhythmias, especially in severe cases 1, 3

Core temperature measurement is ideal but often unavailable in field settings, so treatment decisions must be guided by clinical signs and symptoms 1.

Mild Hypothermia (32-35°C)

Clinical presentation: Alert but shivering, altered level of responsiveness 1

Management approach:

• Passive rewarming with blankets is often adequate for healthy individuals 1
• Increase environmental temperature 4, 2
• Provide high-calorie foods or drinks if patient is alert and can safely swallow 1
• Active rewarming methods may be used in tandem with passive measures 1
• Seek additional medical care 1

Passive rewarming alone allows the body to generate heat through shivering, which can achieve rewarming rates up to 3.6°C/hour 2.

Moderate Hypothermia (28-32°C)

Clinical presentation: Decreased level of responsiveness, may or may not be shivering 1

This is a medical emergency requiring active intervention 1:

• Continue all Level 1 interventions (passive rewarming) 4, 2
• Apply forced-air warming blankets (e.g., Bair Hugger) to achieve approximately 2.4°C/hour rewarming rate 4, 2
• Use heating pads, radiant heaters, or water-circulating warming blankets 4, 2
• Administer warmed intravenous fluids 4
• Provide humidified, warmed oxygen 4
• Activate emergency response system 1
• Place insulation between heat source and skin, monitor frequently for burns 1

Critical caveat: Do not rely on passive rewarming alone at 33°C or below—active measures are mandatory 4.

Severe/Profound Hypothermia (<28°C)

Clinical presentation: Unresponsive, may appear lifeless, slow heart rate and breathing, cessation of shivering, high risk for cardiac arrest 1

This requires immediate aggressive intervention 1, 3:

• Continue all Level 1 and Level 2 interventions 3, 2
• Activate emergency response system immediately 1, 3
• Monitor core temperature every 5 minutes 4, 3
• Consider active core rewarming methods:
  • Warmed IV fluids 1, 3
  • Heated humidified oxygen 1, 3
  • Peritoneal lavage with warmed fluids 2
  • Extracorporeal rewarming (cardiopulmonary bypass, ECMO, hemodialysis, or venovenous hemofiltration) for cardiac arrest or hemodynamic instability 1, 5, 6, 7

For patients with cardiac arrest: Cardiopulmonary bypass provides the most rapid rewarming 1. Alternative effective methods include warm-water thoracic cavity lavage and extracorporeal blood warming 1. Intermittent hemodialysis can achieve stable rewarming at approximately 2.0°C/hour in hemodynamically unstable patients without cardiac arrest 6.

Rewarming Targets and Monitoring

Target a minimum core temperature of 36°C before considering the patient stable 4, 3, 2:

• Cease active rewarming at 37°C—higher temperatures are associated with poor outcomes 4, 3, 2
• Monitor continuously for rewarming complications: cardiac arrhythmias (particularly bradycardia), coagulopathy, rebound hyperthermia, electrolyte abnormalities (especially post-dialysis hypophosphatemia and rebound hyperkalemia), hyperglycemia, and hypotension 4, 3, 6
• Each 1°C decrease in temperature causes 10% reduction in coagulation factor function 2
• Temperatures below 34°C compromise blood coagulation 2

Special Considerations and Pitfalls

Common pitfalls to avoid:

• Never use cold IV fluid boluses for accidental hypothermia—this is only for therapeutic hypothermia 4
• Do not delay urgent procedures like airway management or vascular access due to concerns about cardiac irritability 1
• Avoid axillary temperature measurements as they read 1.5-1.9°C below actual core temperature 4
• If patient cannot be moved from cold environment and is wearing damp (not saturated) polyester fleece, initiate active rewarming through the damp clothing using hypothermia wrap technique with chemical heat blankets 1

Indicators requiring emergency activation: Unresponsiveness, inability to remain awake, mumbling speech, confusion, inability to participate in clothing removal, pallor, cyanosis, or frozen skin 1.

Prevention emphasis: Hypothermia is often overlooked during initial resuscitation; prevention is easier than treatment once significant heat loss has occurred 2. Early organized prehospital hypothermia protocols can reduce incidence from 19% to 3% 2.