Hypothermia

Although it would seem unlikely we would encounter hypothermia with our CVHC geography, it is not impossible. The following scenarios might place a hiker at risk:

  • Hiking at higher altitude with insufficient layers and especially if there is wind
  • Rain that wets clothing, at lower ambient temperatures

Definition:

Core body temperature less than 95 degrees F. However, you’re probably not going to have a thermometer in the field. Below are signs and symptoms to watch for:

  • Mild (95–89.6°F / 35–32°C)   Shivering, cold extremities, impaired coordination, fast heart rate, urinary urgency, alert but may show poor judgment
  • Moderate (89.6–82.4°F / 32–28°C)   Shivering slows or stops, confusion/apathy, slurred speech, drowsiness, stumbling, impaired consciousness
  • Severe (< 82.4°F / < 28°C)   No shivering, muscle rigidity, unconscious, very slow or absent pulse, cardiac arrhythmias, may appear dead

Treatment by Stage:

All Stages:

  • Remove from cold/wind/water. Remove wet clothing (cut off if needed) in a sheltered area.
  • Insulate from the ground and environment: use a vapor barrier (tarp, plastic sheet) plus dry insulating layers.                                                                                                                                                                 
  • Handle gently — rough movement can trigger fatal cardiac arrhythmias.

Mild Hypothermia

  • Encourage movement and shivering (the body’s most effective rewarming tool).
  • Provide warm, sweet drinks and high-calorie food.
  • Apply dry insulation; may use external heat sources (warm water bottles, heat packs to trunk).
  • If fully recovered and risk factors resolved, evacuation may not be necessary.

Moderate Hypothermia

  • Do NOT allow the patient to walk or move themselves.
  • Keep horizontal at all times to prevent cold blood from rushing to the heart (afterdrop).
  • Apply active rewarming: large heat packs or warm water bottles to the trunk (armpits, chest, groin) — NOT to extremities.
  • Evacuate to a hospital.

Severe Hypothermia

  • Treat as above for moderate hypothermia.
  • Check pulse for 60 seconds before starting CPR — pulse may be very slow and faint.
  • If no pulse detected, begin CPR.
  • Evacuate immediately to a hospital. See: https://cvhikingclub.net/initiating-a-rescue-2/
  • Continue CPR during transport — survival with full neurologic recovery has been reported after hours of CPR.

Key Reminders

  • “No one is dead until they are warm and dead.” Do not stop resuscitation in the field.
  • Avoid giving food or drink to anyone who is not fully alert.
  • Small chemical hand warmers are insufficient for core rewarming — use large heat packs applied to the trunk.
  • After cold water rescue, watch for sudden collapse (“circum-rescue collapse”) even after removal from water.

Prevent hypothermia: stay dry, layer clothing, eat and drink regularly, recognize early signs in companions.

(Sources: Wilderness Medical Society (WMS) Clinical Practice Guidelines For the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2019 Update.)   

 The information provided on this CVHC page is for general informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment.