What are the risks and treatment options for hypothermia?

Hypothermia: Risks and Treatment

Hypothermia carries significant mortality risk (approximately 1,300 deaths annually in the United States) and requires immediate intervention with both passive and active rewarming techniques, with treatment intensity escalating based on core temperature and clinical presentation. 1

Major Risks and Complications

Mortality and Morbidity

• Death rates are highest among men, the elderly, and rural populations 1
• In trauma patients, hypothermia increases mortality dramatically: 7% in normothermic patients versus 43% in hypothermic patients 2
• Temperature below 34°C carries an independent mortality risk exceeding 80% in trauma patients requiring massive transfusion 1

The "Lethal Triad"

• Hypothermia combines synergistically with acidosis and coagulopathy to create a lethal triad that dramatically worsens outcomes 1, 2
• Each 1°C drop in temperature reduces coagulation factor function by approximately 10% 1
• Even mild hypothermia (32-35°C) impairs platelet function and increases bleeding risk 2
• Severe hypothermia (<32°C) significantly affects clotting factor activity and fibrinogen synthesis 2

Cardiovascular Complications

• High risk for cardiac arrhythmias, particularly atrial and ventricular dysrhythmias 1, 3
• Profound hypothermia (<24°C) causes slow heart rate, slow breathing, and risk of cardiac arrest 1
• Gentle handling is critical in severe hypothermia to avoid triggering fatal arrhythmias 1, 4

Other Physiological Derangements

• Central nervous system depression progressing with severity 1, 5
• Enzyme inhibition and altered fibrinolysis 1
• Increased transfusion requirements and blood loss 1

Treatment Algorithm by Severity

Cold Stress (35-37°C)

• Remove from cold environment immediately 1
• Remove wet clothing 1
• Passive rewarming with blankets is often adequate in healthy individuals 1
• Provide high-calorie foods or drinks if alert and able to safely consume 1, 4

Mild Hypothermia (32-35°C)

• Continue all cold stress interventions 4
• Protect patient from falls due to altered responsiveness 1
• Use both passive AND active rewarming methods in tandem 1, 4
• Active external rewarming includes heating pads, forced warm air blankets, and chemical heat blankets 4
• Seek additional medical care 1

Moderate Hypothermia (28-32°C)

• This is a medical emergency—activate emergency response system immediately 1
• Continue all measures for mild hypothermia 4
• Use all available passive and active rewarming methods simultaneously 1
• Administer warmed intravenous fluids 4
• Provide humidified, warmed oxygen 4
• Handle patient gently to avoid triggering arrhythmias 1

Severe/Profound Hypothermia (<28°C)

• Continue all moderate hypothermia interventions 4
• Patient may appear lifeless or unresponsive 1
• Consider active core rewarming methods including body cavity lavage and extracorporeal blood warming 4, 5
• Extremely gentle handling is critical 1
• Continuous cardiac monitoring essential 4

Critical Treatment Principles

Universal First Aid Measures (All Severities)

• Move to warm environment as first priority 1
• Remove all saturated clothing immediately 1
• If cannot move to warm environment: insulate from ground, cover head and neck, shield from wind with plastic/foil layer plus dry insulating layer 1
• Place insulation between any heat source and skin to prevent burns 1
• Monitor frequently for burns and pressure injuries 1

Active Rewarming Techniques

• Passive rewarming alone may actually cause temperature decrease during transport in trauma patients 1
• Active rewarming is superior to passive methods, producing +0.74°C increase versus temperature decrease with passive methods alone 1
• Chemical heat packs are effective but should never be placed directly on skin 1
• Body-to-body rewarming is NOT recommended over other active techniques 1

Rewarming Targets and Monitoring

• Target minimum core temperature of 36°C before transferring between units 4
• Cease rewarming after reaching 37°C—higher temperatures are associated with poor outcomes 4
• Monitor core temperature every 5-15 minutes depending on severity 4
• Watch for rewarming shock during the process 4

Special Populations and Contexts

Trauma Patients

• Prevention is more effective than treatment—emphasis should be on prevention first 1
• Hypothermia is often poorly recognized (temperature documented in only 38% of trauma admissions at one major center) 1
• Anesthesia induction causes temperature decrease of 1.6 ± 0.3°C within first hour 1, 2
• Structured protocols reduce hypothermia incidence from 19% to 3% 1

High-Risk Groups

• Very young and very old have reduced thermoregulatory capacity 1, 2
• Patients with impaired temperature perception, regulation, or communication ability 1
• Those with endocrine disorders (hypothyroidism, hypoadrenalism, hypoglycemia) 2
• Spinal cord injury patients (disrupted autonomic control) 2

Critical Pitfalls to Avoid

• Never rely on clinical presentation alone—a rare case report documented a patient alert and communicative despite core temperature of 25.1°C, emphasizing that core temperature measurement is mandatory 6
• Do not use standard thermometers—low-reading thermometers are required for accurate diagnosis 6
• Avoid rough handling in moderate to severe hypothermia (can trigger fatal arrhythmias) 1
• Do not apply heat sources directly to skin without insulation 1
• Recognize that coagulation tests run at 37°C in the lab may not detect hypothermia-induced coagulopathy 1
• Be aware of potential hypothermia-rewarming injury with improper rewarming techniques 3