Rescue and initial resuscitation in hypothermia

As with other emergency situations, the safety of the rescuer is paramount in rescue and initial resuscitation of a patient with hypothermia; risks such as avalanche or drowning must be considered. In deciding what measures are feasible in the field, the first responder must assess:

  • safety of the rescue party
  • resources available
  • likelihood of patient survival (eg whether any fatal injuries are present)
  • competing priorities of starting interventions in the field versus expediting evacuation and minimising further heat loss.

A key priority in management of hypothermia is to remove the patient from the cold environment without delay to prevent further heat loss. The hypothermic patient must be handled very gently, because any handling can precipitate potentially fatal cardiac arrhythmias. The need for removal from the cold environment must be balanced with the need to start interventions.

Note: Handle hypothermic patients very gently to reduce the risk of precipitating fatal cardiac arrhythmias.

Triage of severely hypothermic individuals can be challenging in the field because apparent clinical signs of death (eg fixed dilated pupils, apparent rigor mortis or apparent livor mortis [pooling of blood in lower extremities causing discolouration]) are not reliable indicators of outcomes. The saying ‘No one is dead until they are warm and dead’ acknowledges this.

Note: Fixed dilated pupils, apparent rigor mortis or livor mortis do not contraindicate resuscitation in severely hypothermic patients.

Resuscitation protocols in severe hypothermia differ from standard adult basic life support recommendations. Guidelines for severe hypothermia recommend taking extra time to assess for the presence of a carotid pulse because chest compressions in a hypothermic person with even a barely discernible cardiac output could cause rhythm deterioration and loss of perfusionDow, 2019. Take up to 1 minute to feel for a carotid pulse while also observing for any breaths. Breathing and heart rates may both be very slow; breaths may be shallow and the pulse very low in volume. Examination is also more difficult if the examiner’s fingers are cold. Do not perform chest compressions if the person is breathing (even if they are only gasping at a slow rate) or if any carotid pulse is detected.

Note: Take up to 1 minute to detect a carotid pulse and breathing in a severely hypothermic person because chest compressions can cause arrhythmias.

Start cardiopulmonary resuscitation (CPR) (when it is safe for the rescue party) if a person has:

  • no evidence of fatal injury (eg no signs of avalanche asphyxiation by snow packing an airway or an ice mask obstructing it) AND
  • no signs of life.

Perform compressions with ventilation, using supplemental oxygen if available. Compressions should be done at the same rate as in people without hypothermia. The person may have a very stiff chest wall due to hypothermia, making ventilation more difficult.

If it is not feasible or safe to offer immediate continuous CPR, perform delayed or intermittent CPR. Delayed CPR is a delayed start to resuscitation (ideally by no more than 10 minutes). Intermittent CPR consists of 5 minutes of resuscitation at a time, with no more than 5 minutes between episodes of compression.

Note: If immediate continuous CPR is not possible, perform delayed or intermittent CPR because this may still benefit a person with hypothermia.