What are the criteria and treatment for hypothermia?

Hypothermia Criteria and Treatment

Hypothermia should be treated based on severity classification, with passive rewarming for mild cases, active external rewarming for moderate cases, and active internal rewarming for severe hypothermia. 1, 2

Classification of Hypothermia

Hypothermia is defined as a core body temperature below 35°C and is classified into the following categories:

• Cold stress (35-37°C): Alert, possibly shivering 1
• Mild hypothermia (32-35°C): Altered level of responsiveness, shivering 1, 3
• Moderate hypothermia (28-32°C): Decreased level of responsiveness, may or may not be 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 irregular heart rhythm and cardiac arrest 1

Treatment Algorithm Based on Severity

For All Hypothermia Patients:

• Move from cold environment to warm one 1
• Remove wet clothing immediately 1, 2
• Cover with dry insulating layers 1
• If unable to move to warm environment, insulate from ground, cover head/neck, and shield from wind using plastic or foil layer plus dry insulating layer 1

For Cold Stress (35-37°C):

• Passive rewarming is often adequate in healthy people 1
• Provide high-calorie foods or drinks if alert and able to safely consume 1

For Mild Hypothermia (32-35°C):

• Protect from harm such as falls 1
• Use both passive and active rewarming methods 1
• Apply warming blankets 2
• Seek additional care 1

For Moderate Hypothermia (28-32°C):

• This is a medical emergency - activate emergency response system 1
• Use all available passive and active rewarming methods 1
• Apply heating pads, radiant heaters, and forced warm air blankets 2
• Handle patient gently to prevent arrhythmias 1
• If wearing damp (not saturated) clothing and cannot be moved to warm environment, use hypothermia wrap technique with chemical heat blankets, plastic/foil layers, and insulative blankets 1

For Severe/Profound Hypothermia (<28°C):

• Immediate emergency medical attention 1
• Continue all passive and active external warming 2
• Implement active internal rewarming methods:
  • Administer warmed intravenous fluids 2
  • Consider peritoneal lavage with warmed fluids 2
  • Consider extracorporeal blood warming in extreme cases 2, 4

Important Considerations

Monitoring and Safety

• When using rewarming devices, follow manufacturer's instructions, place insulation between heat source and skin, and monitor frequently for burns and pressure injury 1
• Body-to-body rewarming is not recommended over other active rewarming techniques 1
• Target minimum core temperature of 36°C before transferring patients between units 2
• Cease rewarming after reaching 37°C as higher temperatures are associated with poor outcomes 2, 5

Special Situations

• Hypothermia with decreased responsiveness (responding only to loud voice or pain) is a medical emergency 1
• Early organized prehospital hypothermia protocols can significantly reduce hypothermia incidence 2
• Diagnosis should always be confirmed by core body temperature measurement rather than clinical presentation alone, as symptoms may not always correlate with temperature 6
• Rewarming can be accelerated with shivering, up to 3.6°C/hour 2

Pitfalls to Avoid

• Do not delay treatment while waiting for core temperature measurement - implement Level 1 strategies immediately 2
• Avoid rough handling of severely hypothermic patients to prevent arrhythmias 1
• Do not use body-to-body rewarming as primary method 1
• Do not overlook hypothermia during initial resuscitation, as it forms part of the "lethal triad" with acidosis and coagulopathy 3
• Be aware that improper rewarming can potentially cause additional injury, so follow established protocols 7

By following this structured approach based on severity classification, hypothermia can be effectively managed to reduce morbidity and mortality in affected patients.