This month we will look at illnesses caused by excessive heat focusing on heat cramps, heat exhaustion, and heat stroke. While heat related illnesses may not be as exciting as many other wilderness emergencies they can be potentially very serious and strike anyone. Every year in boot camp new recruits suffer from heat illness and die because their bodies are unable to handle the heat load they are exposed to. These are typically young men and are often in good shape. The conditions, which get them in trouble, are often the same conditions faced by outdoorsman in the summer months
Heat illness is defined as your body's inability to deal with a heat stress. Your own body through exertion or from the environment can produce this stress. Backpacking out an Alaskan moose in late August will generate a lot of body heat. If you are unable to rid yourself of the heat that your body is producing you could be in trouble. Summer hog hunters and antelope hunters will be more familiar with environmental heat. Sitting on a windmill in 90 degree weather in full camo will definitely warm you up. Whether you are producing the excess heat through exercise or it is coming from the environment, your body has three basic mechanisms to deal with the heat load. If the temperature is cooler than body temperature, your body will radiate heat and any breeze will allow convection to dissipate heat. Problems arise when the ambient temperature is in the 90's and you are in full camo. The clothing that works so well in October keeping you warm is now trapping heat around your body and not letting radiation and convection do their job. Another method your body uses to cool itself is through sweating which allows evaporative heat loss. Your body has the ability to sweat more than 2 quarts per hour, which produces excellent cooling. Sweating works great as long as you have fluid to sweat (you are not dehydrated) and the humidity is not so high that evaporation is not possible. Conditions, which hinder any of these cooling mechanisms, can get you into trouble. Your body is designed to run over a very narrow temperature range and will attempt to use the mechanisms outlined above to keep your temperature within that range. High ambient temperatures with high humidity are a recipe for disaster. Radiation and convection are taken out of play and sweating is less effective than usual because of the humidity. If you get even slightly dehydrated and your sweat production decreases your body could be overcome with the heat stress and you will become ill. How you deal with the problem at this stage determines whether you make a full recovery or suffer more severe consequences.
Heat cramps are typically caused by significant exertion accompanied by intense sweating. Your sweat contains lots of salt. If you drink plenty of water but do not replace your salt losses you may experience heat cramps. Your muscles become irritable because the normal chemical balance has been upset and you experience a cramp. The treatment is usually straightforward. Gentle stretching of the muscles combined with fluid and salt replacement. Any of the sports drinks such as Gatorade provide plenty of electrolytes in an easily digestible form. These are much better tolerated than salt pills, which can be very irritating to your stomach.
Heat exhaustion is a more severe condition. This is the most common form of heat illness. It most commonly afflicts unacclimatized people who exercise hard during periods of high temperatures and humidity. These people sweat heavily but do not replace their fluid and salt losses. As they become more dehydrated they may experience headache, confusion, weakness, muscle cramps, and loss of coordination. Their internal body temperature is elevated but their skin may feel cool and clammy. This is because their body is beginning to shut down because of fluid loss. At this stage people can recover if they are removed from the heat and given lots of fluids containing a balanced salt solution. A cool spot in the shade, and cold fluids can turn this condition around. If the person is vomiting such that they are unable to drink fluids they will need medical care so that fluids can be given intravenously.
Heat stroke is the most serious heat illness and is a progression from heat exhaustion. If the person continues to overheat and lose fluids their organs will begin to shut down and they can quickly die. The brain is very sensitive to heat and will swell as your body temperature rises. This will cause loss of consciousness and possibly seizures. Damage to the liver and kidneys also occur, as body temperature becomes extreme. The victim will go into shock and at this stage can only be saved through aggressive medical care. The most important thing you can do is immediately cool the victim. The best way to accomplish this is to remove all clothing and mist the body with water and use a fan or breeze directly on the victim. This has been shown to be the most effective cooling method as it simulates sweating. Placing the victim's body in cold water is not as desirable as the patient is often not coherent and they can be difficult to control while in the water. Only give fluids by mouth if the person is awake and alert. Cooling should be started immediately and continued while heading to the nearest hospital. This is a medical emergency and people will die if not aggressively treated.
With a bit of common sense most heat illness can be prevented. If you kill a big elk or moose and are in for a tough packing job pretend to sprain your ankle and make your buddies pack it out! Seriously, if possible taking a couple of days to acclimate to the hotter temperatures will allow your body to adjust and alter your sweat content. Always stay hydrated by drinking lots of water and sports drinks. If you are drinking plain water, eating salty foods will help replace your electrolytes. Your urine should be clear if you are drinking enough fluids. Thirst is not an accurate measurement of dehydration. In high heat situations you should drink at least 4-5 quarts of fluid per day whether thirsty or not. Dark urine is a warning to increase your fluid intake. Dress in layers and remove clothing as the temperature dictates. Dip your clothing in water or take a swim. If you start to feel dizzy or faint get out of the sun and drink more fluids. By following these simple measures you can minimize the risk of heat related illnesses and help others when the need arises.
Next month; Altitude sickness