| | Problems related to extreme environments
Bengt Kayserell
(prepared by Dr. Olivier Dériaz, SUVA, Sion)
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| Thermoregulation |
| Thermoregulation:
Mechanisms which maintain a constant body temperature |
| Thermoneutral temperature:
Temperature at which the body doesn't fight cold or heat:
28 C outdoors in a bathing suit
34 C in the water in a bathing suit
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| Thermoregulation (Part 2) |
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| Heat production and transfer to the skin |
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| Fighting cold: increasing heat production |
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| Fighting cold: increasing heat production |
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| Fighting cold: increasing heat production |
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| Exercise decreases the temperature |
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| Heat production: shivers |
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| Heat loss by radiation |
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| Heat loss by conduction |
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| Heat loss by convection |
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| Fighting cold |
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| Effect of cold on the organism
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| | Reduction of skin blood flow
Risk of frostbites at the extremities
The body sacrifices its extremities in order to preserve central temperature. |
| Acclimatization |
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| Clothes reduce heat loss |
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| Clothes reduce thermoneutral temperature |
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| IGLOO - Reduction of heat loss
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| Cold - exposed places and protection |
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| Clothes and exercise |
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| Alcohol and exercise in cold weather |
| | Alcohol is harmful especially during long exposures to cold
Hydration
A sensation of cold delays the outbreak of shivers, even in presence of hypothermia
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| Heat loss by evaporation |
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| Heat loss by evaporation |
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| Complications due to heat stress |
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| Heat cramps |
| Symptoms | | Cramps or muscular spasms
Body temperature isn't high |
| Mechanism | | Probably due to a loss of electrolytes
(while sweating) after sustained exercise |
| Prevention | | Ingestion of large quantities of water and electrolytes |
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| Thermoregulation (summary) |
| | The human being is a tropical « animal »
The thermoneutral temperature for a naked human being is 28 C
Hotter environment (> 28 C)
Regulation: heat loss by perspiration
Colder environment : < 28 C
Regulation through clothes or exercise
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| | Altitude physiology |
| Oxygen pressure according to altitude |
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| Effects of altitude: summary |
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| Effect of hypoxia |
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| Effect of a long stay on oxygen transport |
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| Effect of altitude on the endurance performance |
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| Acute mountain pathology |
| | Unknown risk factors:
Isn't related to the alpinist's age, sex, training and experience
Favoured by fatigue and a quick climb in high altitude
Some persons are predisposed
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| Acute mountain sickness |
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Quick climb in altitude
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| Relapses: | | possible after a ten-day descent in the plains |
| Evolution: | | no symptoms during 6-12h, maximum 2-3 days |
| Symptoms: | | fatigue, insomnia, headache |
| Effect: | | 9% 2850m,
50% 4000 et 5000m |
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| Acute mountain pathology (summary) |
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| Treatment of acute mountain sickness |
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