23.10 — Heat Stroke, Hypothermia and Drowning

A person pulled from cold water with no pulse, no breathing and a core temperature of 13.7 degrees made a full recovery.

Anna Bågenholm, a Swedish radiologist, fell through ice in 1999 and was submerged for around 80 minutes. She had been in cardiac arrest for over two hours by the time she was rewarmed on bypass. She returned to work.

Which is the reason for the rule that governs cold emergencies: not dead until warm and dead.

Cold slows metabolism so profoundly that the brain survives without circulation for far longer than it otherwise could. CPR in hypothermia is continued for far longer than usual, and people have recovered completely from what looked like certain death.

This chapter is three environmental emergencies where what feels obvious is frequently wrong.

Heat illness

The spectrum

Heat cramps — painful muscle spasms during or after exertion in heat. Rest, cool, and drink fluids with salt.

Heat exhaustion:

Heavy sweating, pale and clammy skin, headache, dizziness, nausea, weakness, cramps, a fast weak pulse, and a temperature up to around 40 degrees.

And critically: mental state is normal. They are unwell, tired and coherent.

Heat stroke — the emergency:

Core temperature above 40 degrees, and altered mental state.

That combination is the definition, and the mental state is the line between the two conditions.

Confusion, agitation, slurred speech, irrational behaviour, seizures, or unconsciousness.

And a common misconception: the skin may be hot and dry, or it may still be sweating. Classic heat stroke in an older person in a heatwave often presents with dry skin. Exertional heat stroke in a young athlete usually presents with the person still drenched in sweat. Waiting for dry skin costs lives.

Mortality is high and rises steeply with the time spent above the critical temperature. Proteins denature, cells die, and multi-organ failure follows — brain, liver, kidneys, and the clotting system.

Treatment of heat stroke

This is a race. Every minute above 40 degrees causes more damage.

1. Call an ambulance.

2. Move them to shade or a cool place.

3. Remove clothing.

4. Cool aggressively, immediately, and do not wait for the ambulance.

Cold water immersion is the most effective method — a bath, a paddling pool, a tank, or any container of cold water, up to the neck.

Where immersion is not possible: douse continuously with cold water, apply wet sheets with vigorous fanning, and place ice packs at the neck, armpits and groin, where large vessels run close to the surface.

Cool until the temperature reaches around 39 degrees, then stop to avoid overshooting into hypothermia.

And the principle worth stating: in exertional heat stroke, cool first and transport second. The evidence supports cooling on scene rather than losing 20 minutes in an ambulance.

5. Recovery position if unresponsive, and be ready for CPR and for seizures.

6. Do not give fever medicines. Paracetamol and ibuprofen work by resetting the brain's thermostat, and in heat stroke the thermostat is not the problem — the body is being overwhelmed from outside. They do not help and can add liver and kidney injury.

7. Do not give fluids by mouth to anyone confused or drowsy.

Heat exhaustion

Move to a cool place, lie down with legs raised, remove excess clothing, cool the skin, and give fluids — water or an oral rehydration solution.

Should improve within 30 minutes.

If it does not, or if mental state changes at any point, treat it as heat stroke and call an ambulance.

Who is at risk

Older people, particularly those living alone, on diuretics, anticholinergics, antipsychotics or beta blockers — several of which impair sweating or the ability to sense thirst.

Infants and young children, who have a high surface area relative to their mass and cannot remove themselves from the heat.

People with chronic illness, obesity, or dehydration.

Athletes and manual workers in heat, particularly early in a hot season before acclimatisation.

And people in vehicles. A car interior can rise by 20 degrees in 10 minutes, and leaving a window slightly open makes almost no difference. Never leave a child or an animal in a parked car, for any length of time, in any weather warm enough to matter.

Prevention

Drink before you are thirsty, and drink more in heat.

Avoid exertion during the hottest hours.

Light, loose, light-coloured clothing, a hat, and shade.

Acclimatise gradually over 1 to 2 weeks, which produces real physiological adaptation — earlier sweating, more dilute sweat, and increased plasma volume.

Check on older neighbours during heatwaves. Heatwave deaths cluster in isolated older people, and a knock on the door is a genuine intervention.

Keep homes cool: close curtains during the day, open up at night, use fans below about 35 degrees. Above that, fans blowing hot air onto skin can increase heat gain in some conditions, and wetting the skin becomes more important.

Hypothermia

Core body temperature below 35 degrees.

And it does not require extreme cold. Most hypothermia in temperate countries occurs at moderate temperatures, in people who are wet, exhausted, elderly, intoxicated or immobile. A person lying on a cold floor overnight in an unheated house is a classic case.

Water conducts heat around 25 times faster than air, which is why immersion causes hypothermia so rapidly.

The stages

Mild — 32 to 35 degrees. Shivering, cold and pale skin, tiredness, fast breathing, and impaired judgement.

And a genuinely dangerous feature: confusion and poor decision-making appear early, so the person cannot judge their own state. Paradoxical undressing — removing clothing because of a sensation of intense heat as peripheral vessels dilate — occurs in moderate to severe hypothermia and is a recognised finding in cold-weather deaths.

Moderate — 28 to 32 degrees. Shivering stops, which is a bad sign rather than a good one — the body has run out of the energy to shiver. Confusion, slurred speech, drowsiness, slow pulse and slow breathing, and stiff muscles.

Severe — below 28 degrees. Unconsciousness, very slow or undetectable pulse and breathing, dilated pupils, and rigidity.

And at this stage the person can look dead. The pulse may be present but impalpable, breathing may be one or two shallow breaths a minute, and the pupils may be fixed.

Treatment

1. Move them somewhere warm and sheltered, and handle them gently.

Gently is a real instruction. A cold heart is extremely irritable, and rough handling — including carrying someone vertically or jolting them — can precipitate ventricular fibrillation. Move them horizontally where possible.

2. Remove wet clothing, cutting it off rather than manoeuvring them, and dry them.

3. Insulate. Blankets, sleeping bag, foil blanket, and crucially insulation underneath them, because the ground steals heat faster than the air. Cover the head.

4. Rewarm the core, not the limbs.

Warm packs or hot water bottles at the chest, armpits, neck and groin — wrapped, never directly on skin.

Skin-to-skin contact under blankets works.

Warm sweet drinks only if fully conscious and able to swallow safely.

5. Do not rub the skin or the limbs. It does not warm the core and it can damage cold-injured tissue.

6. Do not give alcohol. It dilates skin vessels, increasing heat loss, while producing a false sensation of warmth.

7. Do not put a severely hypothermic person in a hot bath.

Rapid rewarming of the periphery drives cold, acidic blood from the limbs back to the core — afterdrop and rewarming collapse — which can cause cardiac arrest.

A warm bath is reasonable for mild hypothermia in an otherwise well person; severe hypothermia is rewarmed slowly and in hospital.

8. If they are not breathing normally, start CPR — and keep going.

Continue far longer than in normal circumstances.

Check for signs of life for up to a minute before concluding they are absent, because the pulse and breathing may be extremely slow.

Defibrillation and drugs work poorly below about 30 degrees, so the priority is compressions and rewarming.

Hospitals can rewarm using extracorporeal circulation — a heart-lung machine — which is how Anna Bågenholm survived.

And the rule again: no one is dead until they are warm and dead.

Frostbite

Freezing of tissue, usually fingers, toes, nose, ears and cheeks.

Frostnip — reversible, white numb skin, resolving with warming.

Frostbite — hard, white or waxy, numb tissue, with blisters and blackening developing later.

Treatment:

Do not rewarm if there is any chance of refreezing. A freeze-thaw-refreeze cycle causes far worse damage than remaining frozen. If you are still hours from shelter, keep it frozen and get there.

Rewarm in water at 37 to 39 degrees for 15 to 30 minutes, until the tissue is red and pliable. It is extremely painful and needs strong analgesia.

Do not rub, and never rub with snow.

Do not use dry heat — a fire, a heater, a hot exhaust — because numb tissue cannot feel a burn.

Do not walk on frostbitten feet after rewarming, though walking on still-frozen feet to reach safety is acceptable.

Do not burst blisters. Elevate, dress loosely, and get to hospital.

And do not judge the final outcome early. Frostbite frequently looks far worse than it turns out to be, and decisions about amputation are deliberately delayed for weeks, because the tissue that survives is not apparent for a long time.

Immersion foot (trench foot) — from prolonged wet and cold without freezing. Treated by drying, warming and elevation, and prevented by keeping feet dry and changing socks.

Drowning

What actually happens

And the picture most people carry is wrong in every detail.

Drowning is usually silent.

There is no shouting, no waving, no splashing. The mouth is at water level and there is only enough time to breathe, not to call out. The arms press down instinctively on the water surface, so they cannot wave. The body stays upright with no supporting kick.

It typically lasts 20 to 60 seconds before the person goes under.

Which means people drown within metres of others who do not notice, including in busy pools and on beaches with lifeguards.

What to look for: head low with mouth at water level; head tilted back with mouth open; eyes glassy or closed; vertical in the water and not using the legs; hair over the forehead or eyes; hyperventilating or gasping; and appearing to climb an invisible ladder.

Physiologically: water contacting the airway causes laryngospasm and breath-holding. Hypoxia follows, then unconsciousness, then cardiac arrest.

The old distinction between "wet" and "dry" drowning has been abandoned, along with terms like "near-drowning" and "secondary drowning". The current terminology is simply drowning, with outcomes described as fatal or non-fatal.

Rescue

Reach. Throw. Row. Do not go.

Reach with a pole, branch, towel or rope, lying flat and keeping your centre of gravity low.

Throw something that floats, ideally attached to a line.

Row — use a boat or board if available.

Go only if you are trained and equipped. Would-be rescuers drown regularly, frequently parents going in after children, and a second casualty makes everything worse.

Call for help before or while attempting anything.

Treatment

1. Get them out of the water as soon as safely possible.

Keep them horizontal during removal if you can, because immersion causes blood to pool centrally, and lifting someone vertically can cause circulatory collapse.

2. Check airway and breathing.

3. If not breathing normally: give 5 initial rescue breaths, then start CPR.

And this is the key difference from adult cardiac arrest. Drowning is a hypoxic arrest — the problem is a lack of oxygen, not a rhythm disturbance. The blood and lungs are oxygen-depleted, so breaths matter more here than in any other adult arrest.

Compression-only CPR is much less effective in drowning. Give breaths if you possibly can.

Rescue breaths can be started in the water by a trained rescuer, and compressions cannot.

4. Do not attempt to remove water from the lungs.

No abdominal thrusts, no turning upside down, no pressing the abdomen. Very little water actually enters the lungs, the manoeuvres delay effective CPR, and they cause vomiting and aspiration.

Vomiting during resuscitation is very common in drowning — expect it, turn the head to the side, clear the mouth, and continue.

5. Assume hypothermia and possible spinal injury.

Spinal injury is uncommon in drowning overall, and is considered where there was a dive, a fall, a surfing accident, or signs of trauma.

Remove wet clothing and insulate.

6. Continue CPR for longer than usual, particularly in cold water, for the reasons at the top of this page.

7. Everyone who has been rescued from drowning needs medical assessment, even if they seem completely well.

Water in the lungs damages surfactant and can cause deteriorating breathing over the following hours (Chapter 8.2). Symptoms to watch for over the next 24 hours: persistent cough, breathlessness, chest pain, extreme fatigue, or any change in behaviour or alertness.

Anyone with a persistent cough, any breathing difficulty, any period of unconsciousness, or who needed any resuscitation goes to hospital.

Prevention

Drowning kills an estimated 236,000 people a year, and it is a leading cause of death in children worldwide.

Supervision — constant, undistracted, and within arm's reach for young children. Most young child drownings occur during a brief lapse, and a phone is the commonest distraction.

Barriers — four-sided isolation fencing around pools reduces child drowning substantially, more than any other single measure.

Learn to swim, and teach children.

Life jackets on boats, and for weak swimmers near water.

No alcohol around water. Alcohol is involved in a large proportion of adult drownings.

And a specific danger: cold water shock.

Sudden immersion in water below about 15 degrees causes an involuntary gasp, uncontrollable hyperventilation, and a surge in heart rate and blood pressure. This is what kills people in the first minute, before hypothermia has any chance to develop.

The advice that saves lives: float first. Lean back, extend the arms and legs, and float for 60 to 90 seconds until the gasping reflex passes and control returns. Then swim or call for help.

Fighting it in the first minute is what causes people to inhale water.

And in home settings: empty paddling pools and buckets, use toilet lid locks with toddlers, and never leave a young child alone in a bath for a moment. A child can drown in a few centimetres of water.

The three rules

Heat stroke: temperature plus confusion. Cool aggressively and immediately, on the spot.

Hypothermia: handle gently, rewarm the core, and continue CPR far longer than usual.

Drowning: reach, throw, row — do not go. Give breaths first. Never remove water from the lungs. And everyone gets assessed afterwards.

What the next page fixes

Chapter 23.11 covers diabetic and seizure emergencies — two situations that occur constantly in daily life, and where a bystander who knows one simple rule can end the crisis in minutes.