What is hypothermia and how to avoid it while trekking

The recent tragedy at Omasi La raises the question if “PanditJi” was hypothermic after a cold stream crossing and whether hypothermia led to other serious complications. However, in hindsight, our interpretation of events is merely a conjecture. What is important for a trekker venturing out in the Himalayas, is the ability to recognise, avoid and if necessary deal with hypothermia.

“They considered their options and decided to follow the apparently less difficult trail, which obviously meant crossing the bone-chilling waters of the waist-deep stream ahead. It was not before 1530 Hours that they crossed the river. The sky was overcast, the summit just within the reach but Pandit Ji just couldn’t walk…He tried to move out of the tent but his legs were frozen like wood. He felt exhausted and he just couldn’t get on his feet once he sank in his sleeping bag. Rijul prepared tea for him and massaged his legs mercilessly but that just wouldn’t work.” - What happened at Omasi La?

Table Of Contents

What is Hypothermia

”Hypothermia is a decrease in the core temperature of the body that impairs intellectual, muscular, and cardiac function.” — James A. Wilkerson, Medicine for Mountaineering, 5th ed.

What Causes Hypothermia

  • Inadequate clothing.
  • Cold temperature.
  • Wet environment.
  • Older age.
  • Exhaustion.
  • Dehydration.
  • Poor food intake.
  • Alcohol intake.

Hypothermia Myths

  1. Hypothermia can only happen in extremely cold weather, generally below freezing. Hypothermia does not require below freezing temperatures. You could just as easily get hypothermia in cool, windy and wet conditions.
  2. A rub or a massage cures hypothermia . Rubbing or massaging is not helpful, especially in icy conditions where frostbite may be a possibility. Rubbing a frostbite victim may lead to more tissue damage. A hypothermic victim needs gentle, slow handling.
  3. Drink liquor to warm up . While alcohol may have a place in some survival scenarios, it is a big no-no in a cold-weather exposure situation. Alcohol is a vasodilator which means that it pushes the blood to the skin. While a rush of blood to the skin may dull the pain of the cold and make you feel warmer, it is achieved at the cost of chilling your core which is far more dangerous.
  4. The more beard and head hair, the more warmth. Hair is not fur and it is not dense enough to make a difference when it comes to losing heat.

How Do We Lose Heat

  • Conduction – Heat moves through solid substances by this process. Conduction is typically measured with an R-value (the higher the number, the greater resistance to heat flow). Anything that conducts electricity typically has a low R-value. Metals of all kinds fall into this category. Wood, not a good conductor, has a higher R-value than metal. Water conducts heat away from the body 25 times faster than air. Generally conductive heat loss accounts for only about 2% of overall heat loss in a human body. However, with wet clothes this loss is increased by 500%.
  • Convection – is the movement of liquids and gases because of differences in density. Convection explains why warm air ends up in the upper floors of a house while the basement stays cold, or why a chimney draws smoke up and out of the house. Wind Chill is an example of heat loss through convection.
  • Radiation – is the movement of energy from a hot object to a cooler one via waves. Think of the sun on a hot summer day. The air temperature is the same in the sunshine as it is in the shade, but we feel more comfortable when we get out of the sun and out of reach of all that radiant energy.
  • Evaporation – is the heat loss from converting water from a liquid to a gas. e.g. Perspiration and respiration. As body moisture is lost through the various evaporative processes, the overall circulating volume is reduced. If this volume is not frequently topped up, it may lead to dehydration. Dehydration makes the body more susceptible to hypothermia and other cold injuries.

How Does Our Body Maintain Core Temperature

  • Vasoconstriction. Decreasing blood flow to extremities, decreases heat loss. Maximal vasoconstriction can decrease skin blood flow to 30 ml/minute (average flow is 300-500 ml/minute).
  • Shivering. Visible shivering increases your surface heat production between 200 to 500% that of your normal, resting rate. However, this is limited to a few hours because of the depletion of muscle glucose and the onset of fatigue

An experienced trekker will always keep an eye out for “-Umbles” – stumbles, mumbles, fumbles, and grumbles which show changes in motor coordination and levels of consciousness.

Types Of Hypothermia & Its Symptoms

Mild Hypothermia (97 – 95°F)

Goose bumps, shivering, numb hands and cold feet due to vasoconstriction.

Moderate Hypothermia (95 – 90°F)

Clumsiness and uncoordinated behaviour, movements slow and laboured, amnesia starts to appear, difficulty speaking, depression, withdrawn.

Severe Hypothermia (90 – 75°F)

Shivering stops, exposed skin blue of puffy, stupor, loss of awareness of others, pulse and respiration rate decrease, unconscious, pulmonary oedema, cardiac and respiratory failure leading to death.

Treating Hypothermia

The key to treating Hypothermia is early detection. If hiking in a group, it is a good idea to assign buddies and to check them for changes in behaviour. When trekking solo, one has to vigilantly monitor one’s physical and mental state. If hypothermia is suspected, the treatment is to reduce heat loss, conserve body heat and replace body fuel to generate more heat. Heat loss may be reduced by -

  • Dry clothing
  • Additional layers of clothing
  • Increased physical activity
  • Providing shelter
  • Getting into a dry sleeping bag, use extra sleeping mats for ground cover
  • Sharing a sleeping bag with a dry person
  • Lighting a fire or a stove

Body fuel may be replaced by

  • Warm (not hot) liquids like cocoa, tea, warm water with added sugar. Alcohol, coffee and nicotine should be avoided.
  • Good old Raisins and Peanuts (GORP) provides both carbohydrates and fat.

In case of severe hypothermia, it may be essential to reheat the patient’s core. Only reheat the core as reheating the extremities could lead to *”afterdrop”*. A heat source should be applied to major arteries – at the neck for the carotid, at the armpits for the brachial, at the groin for the femoral, at the palms of the hands for the arterial arch. Chemical heat packs and metal drinking water bottles filled with hot water may be used for this purpose.

Afterdrop is a situation in which the core temperature actually decreases during rewarming. This is caused by peripheral vessels in the arms and legs dilating if they are rewarmed. This dilation sends this very cold blood from the periphery to the core further decreasing core temperature which can lead to death. Remember, rewarm the core! Do not expose a severely hypothermic victim to extremes of heat. ~ Outdoor Action Guide. Princeton University

How To Avoid Hypothermia While Trekking

  • Pre trek preparation, check weather forecast - Before you head out for a trek in the Indian Himalayas, know the forecasted wind chill, moisture levels, and temperature ranges for that duration. Accuweather provides reasonably accurate weather forecast even for remote areas in the Indian Himalayas. On most multi-day treks we do not receive a data connection on our mobiles. In such situations we appoint a responsible person in the city who will monitor the weather updates and provide us daily weather updates via SMS.
  • Weather Awareness - Despite the weather forecast, weather conditions often change at higher altitudes. Keep an eye out for signs of deteriorating weather. If you have a watch/GPS with a built-in barometer, keep an eye out for dropping air pressure. Clouds can often be used to gauge weather condition in the mountains. The appearance of lenticular clouds in the Himalayas generally mean that a storm will be approaching in the next 6-24 hours. If you are caught in inclement weather, don’t hesitate to put up your shelter and re-evaluate your plans for the trek. Remember Safety First!
  • Appropriate clothing - Layer your clothes to maximise warmth and make sure your extremities like fingertips, feet and head are covered.
  • Avoid sweating - Sweating is body’s way of reducing temperature through evaporation. In cold weather treks make sure you set a pace that does not lead to excessive perspiration.

If you can hold a conversation without slurring or running out of breath then your current pace is right. This a simple check that you can use to pace yourself on a trek.

  • Short breaks - When you stop moving, your body tends to cool much faster. Short breaks ensure that this is kept to a minimum. Short breaks in conjunction with the right pace keeps your core temperature regulated.
  • Food - Food is the fuel required by the body, to generate heat. Prefer Small snacks at regular intervals rather than large meals at longer intervals on multi-day treks.
  • Hydration - Lot of trekkers forget to hydrate on a cold day. Remember that a lack of hydration may lead to an early onset of hypothermia.


It is easy to remember a checklist. To keep yourself WARM, remember the word COLD.

  • C - Keep yourself and your clothes Clean. Clean clothes have a greater insulating value
  • O - Avoid Overheating. Try to avoid perspiring.
  • L - Wear clothes Loose and in Layers. Layers trap pockets of air adding insulating value.
  • D - Keep Dry. Wet clothes loose up to ninety per cent of their insulating value. If your clothes become wet, change clothes or dry them immediately!