Hypothermia for paramedics: gentle hands, honest rewarming and what 'not dead until warm' really means

A snowmobiler went through the ice near the shore of a northern Ontario lake late in the afternoon. Friends pulled him out quickly, but by the time the crew reaches him he has been lying on the snow in wet clothes for a long while. He is shivering hard, mumbling, and wants to stand up and walk to the truck: a classic opening to a hypothermia paramedic call.

The crew says no. That single decision, made in the first minute, captures most of what this kind of call is about: the cold patient is fragile in ways that are easy to forget when they look like they could walk.

This case breakdown is a composite built for teaching. Exact treatments, temperatures and destination rules belong to your service's medical directives and your provincial standards.

#The first hypothermia paramedic priority: stop the heat loss

The first priority is not rewarming. It is stopping things from getting worse.

• Get out of the wind and off the ground. Insulate from the snow before anything else.
• Remove wet clothing carefully, cutting rather than pulling where needed, and replace it with dry insulation.
• Wrap in layers with a vapour barrier and an outer windproof layer if available.
• Cover the head and neck.
• Warm the ambulance ahead of loading.

Shivering is useful: it means the body is still making heat. A patient who stops shivering while still cold is getting worse, not better.

#Gentle handling and staying horizontal

A cold heart is irritable. Rough handling, sudden position changes and letting the patient walk are associated with dangerous rhythms and with blood pressure dropping when they are moved upright.

For this reason the crew:

1. Keeps the patient horizontal throughout.
2. Moves him as a unit, slowly and deliberately, with enough hands.
3. Avoids unnecessary procedures on scene.
4. Puts on the cardiac monitor early.

Staging of hypothermia in the field is usually clinical, based on consciousness and shivering, because accurate core temperatures are hard to obtain prehospital. The Swiss staging system described in hypothermia guidelines is one widely used example.

#Rewarming and the wider assessment

#Rewarming within the limits of an ambulance

Prehospital rewarming is mostly passive and active external:

• Passive: dry insulation and a warm environment so the body's own heat production works.
• Active external: heat packs or warming blankets applied to the trunk, not the limbs, as your directives describe.
• Warmed IV fluids, if part of your directives, mainly to avoid adding cold rather than as a strong rewarming tool.

Be honest about what the ambulance can do. External measures help a shivering patient a great deal, but a patient with moderate or severe hypothermia needs in-hospital rewarming, and getting there safely is the real treatment.

#Watching for the hidden problems

Cold rarely travels alone. Before assuming hypothermia explains everything, the crew considers what else could be going on:

• Trauma. A fall through ice, a crash or a collapse may have caused injuries that cold makes harder to detect.
• Hypoglycemia. Cold, exertion and alcohol can all lower glucose, and confusion overlaps with both conditions.
• Intoxication or overdose, which can be both a cause of exposure and a complication of it.
• An underlying medical event, such as a stroke or cardiac problem, that led to the person being outside and down in the first place.

A glucose check and a careful secondary survey, done gently, belong in every cold-exposure assessment.

#When the cold patient arrests

En route, the snowmobiler becomes less responsive. Then the monitor changes.

Cardiac arrest in hypothermia is where "you're not dead until you're warm and dead" comes in. The phrase captures something real: profound cold can protect the brain, and there are well-documented survivors after long resuscitations with good neurological outcomes.

The nuance matters just as much:

• Check for signs of life carefully. Pulses and breathing can be very slow and faint. Hypothermia guidelines recommend taking longer than usual to assess before starting CPR.
• Some cold patients are not salvageable. Obvious lethal injuries, a body frozen solid or, in avalanche burial, specific factors described in the guidelines may mean resuscitation is not appropriate. Your directives and online medical control guide this.
• Defibrillation and drugs may behave differently in the very cold heart. Guidelines describe modified approaches; follow what your directives say rather than improvising.
• Mechanical CPR may help if available, since transport can be long and manual compressions in a moving vehicle are hard to sustain.
• Do not stop simply because time has passed. Termination-of-resuscitation rules for normothermic patients may not apply. Consult online medical direction.

#Destination: where the warm-up can happen

For a hypothermic patient in cardiac arrest, or one who is unstable, international guidelines favour transport to a centre able to provide extracorporeal life support, such as ECMO or cardiopulmonary bypass, where that is achievable. In much of Canada that may mean bypassing the nearest hospital or arranging an air transfer.

Destination questions to settle early, with online medical direction:

• Is there an ECMO-capable centre within a reasonable transport time?
• Does the regional system support bypass or an air intercept?
• Can the receiving team be pre-alerted to prepare?

#For training leads

Many crews see few severe hypothermia cases, so practise the decisions before winter does:

• Run a "patient wants to walk" scenario and grade how the crew handles it.
• Practise the prolonged pulse check in a cold arrest, and the conversation with online medical direction.
• Map your region's ECMO options and make them part of the scenario.
• Rehearse mechanical CPR loading in a moving-vehicle setting.

Repeated scenario practice, including branching cases on Imedica, helps crews rehearse uncommon decisions like these before they meet them on a dark roadside.

#The takeaway

The cold patient needs patience. Stop the heat loss, keep them flat and handle them gently, rewarm within your limits, assess signs of life slowly and treat cardiac arrest in hypothermia as potentially survivable within your directives. Then get them to the place where the real rewarming can happen.

Drafted for Imedica Field Notes. Physician review of this article is pending.