High-Altitude Medical

HANDBOOK

Have you ever been so cold that you started shivering uncontrollably or your teeth were chattering? If so, you have already experienced the early stages of hypothermia.

Hypothermia occurs when the core body temperature drops below (35°C) and the body can no longer maintain proper physiological function.

Preventing hypothermia in the mountains requires good preparation, proper clothing, and maintaining energy and hydration.

HOW TO PREVENT HYPOTHERMIA

Basic prevention measures include:

➤ Wear a layered clothing system appropriate for weather conditions.

➤ Carry high-energy food and drink regularly (at least 4 liters of fluids per day).

➤ Avoid excessive sweating by maintaining a steady climbing pace.

➤ Stay dry whenever possible.

➤ Carry an emergency thermal blanket and a bivy shelter or survival bag.

➤ Seek protection from wind and precipitation whenever possible.

If you suspect hypothermia or injury, wrap the victim in a thermal emergency blanket (silver side toward the body) and get into bivy shelter.

HIGH-ALTITUDE ENVIRONMENT

Conditions in the high mountains are very different from those at low altitude.

Two major environmental threats are:

➤ Reduced oxygen availability

➤ Extreme cold

Air temperature drops about 1°C for every 150 m of altitude gain, increasing the risk of hypothermia and frostbite.

Wind significantly increases heat loss. For example:

➤ −10°C with 50 km/h wind feels like −20°C

➤ −30°C with 50 km/h wind feels like −50°C

On Everest, winter winds can reach 150 km/h, creating perceived temperatures as low as −70°C.

HOW THE BODY LOSES HEAT

In the mountains, the body loses heat through several mechanisms:

Radiation – heat loss to the surrounding environment.

Conduction – direct contact with cold surfaces or wet clothing.

Convection – wind removing heat from the body.

Evaporation – sweating during physical activity.

Respiration – warming cold air inhaled at altitude.

The risk of hypothermia increases when a climber sweats heavily, wets clothing, encounters bad weather, and must unexpectedly stop moving or bivouac.

TYPES OF HYPOTHERMIA

Hypothermia is classified according to core body temperature:

➤ Mild: 35–32°C

➤ Moderate: 32–28°C

➤ Severe: below 28°C

In mountain environments, diagnosis is usually based on symptoms rather than temperature measurements.

MILD HYPOTHERMIA

Early symptoms include:

➤ shivering

➤ feeling very cold

➤ confusion or poor judgment

➤ clumsy movements

➤ slurred speech

MANAGEMENT

At this stage the body can usually rewarm itself through shivering and physical activity, provided further cooling is prevented.

Important actions include:

➤ provide shelter from wind and cold

➤ remove wet clothing if possible

➤ insulate the victim with sleeping bags, pads, or emergency blankets

➤ provide warm, high-energy drinks if the person is conscious

Shared body heat inside a sleeping bag can also be very effective.

Avoid alcohol, as it increases heat loss.

AFTERDROP – A DANGEROUS PHENOMENON

When the body is cold, circulation to the arms and legs decreases to preserve heat around vital organs.

Sudden movement may cause cold blood from the limbs to return to the core, lowering core temperature further. This effect, called afterdrop, can trigger loss of consciousness or cardiac arrest.

For this reason, a hypothermic climber should rest and warm gradually before resuming activity.

MODERATE HYPOTHERMIA

When core temperature falls below 32°C, symptoms worsen:

➤ shivering may stop

➤ severe confusion

➤ drowsiness

➤ slowed breathing and pulse

➤ loss of consciousness

Mental status can be assessed with simple questions such as:

➤ Where are we?

➤ What year is it?

Difficulty performing simple tasks or maintaining balance may indicate impaired brain function.

At this stage the victim cannot rewarm themselves and requires assistance.

MANAGEMENT

➤ Handle the victim very gently to avoid triggering heart rhythm disturbances.

➤ Ensure the airway remains open.

➤ Do not give fluids to an unconscious person.

➤ Continue insulation and passive rewarming.

Evacuation should be arranged as soon as possible.

SEVERE HYPOTHERMIA

In severe hypothermia:

➤ breathing and pulse may be difficult to detect

➤ pupils may be dilated

➤ the body becomes stiff and very cold

A climber who appears lifeless may still be alive.

Unless there are clear signs of irreversible death, resuscitation efforts should be started.

HYPOTHERMIA AND HIGH-ALTITUDE CEREBRAL EDEMA (HACE)

Symptoms of hypothermia may resemble High-Altitude Cerebral Edema (HACE).

Above 3000 m, it may be difficult to determine which condition is responsible for a climber’s symptoms.

In such cases:

➤ treat both conditions

➤ descend to lower altitude immediately

➤ administer oxygen if available

➤ consider portable hyperbaric therapy and dexamethasone

REFERENCES:

• Wilderness Medical Society Clinical Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2019 Update.

• Oxford Handbook of Expedition and Wilderness Medicine; C. Johnson, S.R. Anderson, J. Dallimore, S.Winser, D.A. Warrell; Oxford University Press 2008

• NMS – Emergency Medicine; S.H. Plantz; E.J. Wipfler; Elsevier Urban & Partner 2008.

• Practice Guidelines for Wilderness Emergency Care; W.W. Forgey; Wilderness Medical Society 2006.

• High Altitude Medicine and Physiology; J.B. West, R.B. Schoene, J.S. Milledge; Hodder Arnold 2007.

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WANT TO LEARN MORE?

If you want to better prepare your health for trekking or a high-altitude expeditions, check out the expanded guide in the ebook "High-Altitude Medicine for Trekkers and Climbers" >>

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Gain practical skills for handling emergencies in the mountains through our online training "High-Altitude First Aid" >> - prepared for those planning trips to high altitudes.

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 For a detailed list of what to include in your expedition medical kit and step-by-step instructions for assembling your personal first aid set, see the ebook "High-Altitude Expedition Medical Kit Guide" >>

PLANNING A TREK OR A HIGH-ALTITUDE EXPEDITION?

If you would like to check whether your health condition allows you to safely participate in a trek or high-altitude expedition, consider booking a medical consultation >> or using a telemedical expedition package >>

This allows you to assess potential health risks in advance, prepare properly fot altitude, and increase your safety during the expedition.

The company was established in 2004. The goal of MedEverest is education in the field of mountain medicine and the dangers of high altitudes. I deal with all medical aspects of staying at high altitude. I organize medical support for trekking and high-altitude expeditions.

Specialist Medical Practice Medeverest Robert Szymczak based in Gdańsk (80-360), at ul. Bolesława Krzywoustego 19F, NIP: 5841943576, REGON: 220148318.

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