High-altitude medicine

ZONE OF KNOWLEDGE

Have you ever been so cold that you started shivering and your teeth began to chatter? If so, you have already experienced mild hypothermia, or cold exposure.

Hypothermia is a condition in which the body's core temperature drops below (35°C) and the body cannot function properly.

In the mountains, cold exposure is one of the most common life-threatening hazards, which is why prevention, proper equipment, and appropriate actions in the field are crucial.

HOW TO PREVENT COLD EXPOSURE

Basic prevention guidelines:

➤ wear layered clothing suited to the weather conditions

➤ drink plenty of fluids (at least about 4 liters daily)

➤ consume high-energy foods (bars, gels, snacks)

➤ avoid excessive exertion that causes sweating

➤ try to stay dry

➤ always carry an emergency thermal blanket

➤ in areas at risk of unplanned camping, carry a bivouac tarp or survival tent

The thermal blanket should be used for anyone suspected of hypothermia or injury (with the silver side against the body). Additionally, one should enter the survival tent.

HIGH-ALTITUDE ENVIRONMENTAL CONDITIONS

Conditions in high mountains differ significantly from those we know in lowlands.

The main hazards include:

➤ decreased oxygen availability with altitude

➤ low temperatures

Air temperature decreases on average by 1°C for every 150 m of altitude, increasing the risk of cold exposure and frostbite. At the summit of Everest, the average perceived temperature during the season is around −40°C.

Wind also plays a huge role in lowering the perceived temperature:

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

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

In winter on Everest, winds can reach 150 km/h, which at an air temperature of −40°C results in a perceived −70°C.

MECHANISMS OF HEAT LOSS

The body loses heat in the mountains through several mechanisms:

➤ Radiation – losing heat to the environment.

➤ Conduction – contact with cold ground or wet clothing.

➤ Convection – heat loss due to wind.

➤ Evaporation – heat loss during sweating.

➤ Breathing – warming cold air in the respiratory tract.

The greatest risk of cold exposure occurs when a climber sweats, gets their clothing wet, faces a weather change, and is forced to camp unexpectedly in wind and precipitation.

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 conditions, diagnosis is usually based on clinical symptoms, as accurately measuring core temperature is difficult.

MILD HYPOTHERMIA

Symptoms:

➤ intense feeling of cold

➤ shivering

➤ concentration difficulties

➤ clumsy movements

PROCEEDINGS

At this stage, the body can usually warm itself through shivering and physical activity, as long as we stop further heat loss.

Key actions:

➤ provide shelter from wind and cold

➤ remove wet clothing and replace it with dry

➤ insulate the affected person from the ground

➤ use a sleeping bag, bivouac tarp, or NRC blanket

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

An effective method for warming is also the heat from another person in a sleeping bag. Do not give alcohol – it increases heat loss.

AFTERDROP – A DANGEROUS PHENOMENON

During cold exposure, the body restricts blood flow to the extremities to protect vital organs.

Sudden movement can cause cold blood from the extremities to rush back to the body's core, leading to a further drop in core temperature. This phenomenon is called afterdrop and can lead to loss of consciousness or cardiac arrest. Therefore, a cold climber should rest and warm up gradually before resuming exertion.

MODERATE HYPOTHERMIA

When core temperature drops below 32°C, serious symptoms appear:

➤ cessation of shivering

➤ confusion

➤ drowsiness

➤ slurred speech

➤ balance disturbances

➤ loss of consciousness

➤ slowed breathing and heart rate

Consciousness can be assessed by asking questions such as:

➤ where are we?

➤ what year is it?

Balance disturbances or difficulty with simple tasks may indicate a deteriorating condition of the affected person. At this stage, the affected person is unable to warm themselves.

Proceedings

➤ proceed very gently – sudden movements can cause cardiac arrest

➤ ensure airway patency

➤ do not give fluids to an unconscious person

➤ continue insulation and passive warming

The victim should be evacuated as quickly as possible.

SEVERE HYPOTHERMIA

Symptoms:

➤ undetectable breathing and pulse

➤ dilated pupils

➤ rigidity of the body

➤ very cold skin

In such a situation, a person may appear dead, but they may still be alive. If there are no clear signs of death, life-saving actions should be initiated.

HYPOTHERMIA AND HIGH-ALTITUDE CEREBRAL EDEMA (HACE)

The symptoms of hypothermia can be similar to those of high-altitude cerebral edema (HACE). At altitudes above 3000 m, it can sometimes be difficult to distinguish between the two conditions.

In such a situation, one should:

➤ start treatment for both conditions simultaneously

➤ descend to a lower altitude as quickly as possible

➤ provide oxygen (if available)

➤ consider a hyperbaric bag 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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DO YOU WANT TO LEARNMORE?

If you want to better prepare yourself health-wise for trekking or a high-altitude expedition, you can find the extended version of the guide in the ebook"High Altitude Medicine in Practice – a guide for trekking and expeditions" >>

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You can also gain practical knowledge about emergency procedures in the mountains through the online training"High Altitude First Aid" >> - designed for individuals planning trips to high altitudes.

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Meanwhile, you can find the detailed contents of the expedition first aid kit and precise instructions for preparing the expedition kit and personal rescue set in the ebook"Expedition First Aid Kit – a complete medical guide" >>

ARE YOU PLANNING A TREKOR A HIGH-ALTITUDE EXPEDITION?

If you want to check if your health condition allows you to safely participate in a trek or high-altitude expedition, it is advisable to usea medical consultation >> ora telemedical expedition package >>

This way, you can assess health risks in advance, prepare properly for the trip, and increase safety while at altitude.

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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