Heat Related Illnesses Here in our home state of South Carolina, the opening day of the deer season in much of the state is on August 15th when the temperatures can exceed 100 degrees F and have a humidity index of 90-100%. To compound the problem, a lot of the habitat native is very thick vegetation and swamps in which the preferred method of hunting to many is with hounds and shotguns loaded with buckshot. Now imagine what happens to the hound handlers that release their dogs and then pursue them at a fervent pace thru all that vegetation in the high heat and humidity for hours on end. You got it! It leads to the perfect scenario for any of the heat related illnesses. Within a short period of time, even the best hounds are looking for the nearest pool of water to lie in to cool off and to be honest so are many of the hunters. Acclimation only goes so far! Now I know many of you are asking yourselves why we start hunting so early when the best of the deer season is in October. The reason is that we can, but also the harvest of a few deer in the early part of the season doesn’t hurt our bag limit because in a lot of the state we are allowed up to three deer per day. Basically, it gives an excuse to get out of the house and into the field with our friends. In the last issue of Safari, an excellent article was written by Mr. J. Wayne Fears on the subject of Hypothermia. With the heat of the summer here and of most of the different hunting seasons about to start, we thought it appropriate to complete the cycle by discussing the different kinds of heat related illnesses (Hyperthermia) and their prevention and treatment. Our bodies have a series of complicated mechanisms to regulate our temperature. There is a constant shifting balance between heat production and heat dissipation. Contrary to popular belief, sweating only provides a relatively small contribution to heat loss (30%). Our bodies radiate heat both by convection and conduction to account for 65% of this function with breathing responsible for the remaining 5%. These physiologic adaptations clearly illustrate why both ambient temperature and humidity have such a dramatic impact on our capacity to maintain a steady temperature, and as well, why it is clearly possible to come down with a heat related illness when in a cool environments. By example if ambient temperature is close to or exceeds body temperature (~98.6 F), then no radiant heat loss can occur. As humidity increases, the contribution that sweating can make is also greatly reduced, and the body sweats even more, though with very little effect. Dehydration can result and the stage is set for serious injury or even death. On the other hand, exertion while bundled in layers of heat retaining clothing can limit heat loss to the 5% resultant from breathing and heat related illness can occur in cooler temperatures, albeit treatment is easier in cold temperatures! Heat related illnesses (hyperthermia) that can affect us outdoorsmen can be experienced as 4 individual syndromes ranging from the inconvenient to the fatal. Heat Cramps usually occur in healthy folks who engage in vigorous exertion in hot and humid environments. The most common muscles affected are the leg muscles. The treatment is simple hydration. DO NOT TAKE SALT PILLS without generous amounts of water as a preventative! Salt pills by themselves have killed many an athlete and simple hydration with water or Gatorade type drinks and the cessation of exertion is all that is needed to treat and prevent this syndrome. Heat Exhaustion is the most common form of heat related illness. It occurs in the non-acclimated individual and results from a disturbed fluid and electrolyte balance. Poor physical conditioning, extremes of age and certain medications predispose to this illness. Examples of medications that place you at increased risk include (but not limited to): beta-blockers, diuretics and certain psychiatric meds. The major symptoms of this syndrome include, nausea, vomiting (more fluid & electrolyte loss), dizziness, weakness, irritability, diffuse muscle cramps, abnormal heart rate and breathing and if untreated may progress to heat stroke. Body temperature need not be dramatically high to develop these symptoms. Treatment is simple and involves Gatorade type fluid replacement (IV fluids may be required if unable to keep down oral replenishment) and a cooling environment. Wet towels over the head and draped around the neck can be very helpful here as with all heat related illnesses. Heat Syncope is caused by vigorous exercise by a sub-optimally fit individual. What happens is that the blood vessels in the skin over dilate to hasten the dissipation of the generated body heat. This results in a drop in blood pressure then lightheadedness and finally collapse from fainting. It is self limited, and body temperature may even be normal (thanks to excessive vessel dilation). This is not a particularly serious illness and responds quickly to the cessation of exercise, resting while lying down in a cool environment and Gatorade type fluid replacement. Heat Stroke is a life threatening emergency with a death rate of up to 75%. Because of excessive heat production, and inadequate heat loss, body temperature continues to climb. At or about 106 degrees F body proteins begin to cook. Muscles breakdown leading to kidney failure, the body’s ph falls to dangerously low levels, and pathological changes occur in the blood clotting systems. Finally, profound chemical changes lead to fatal heart rhythms and or brain damage. Heat stroke occurs exclusively in hot and humid environments and is more likely in people who are dehydrated. Risk groups for this syndrome include: age > 50, obesity, cardiovascular disease, alcohol consumption, certain cardiac and psychiatric medicines and (no surprise) illicit drugs of all kinds. Early symptoms resemble other heat related illnesses and include: dizziness & headache. This is followed by confusion, and worsening mental status culminating in delirium, seizures, coma and death. The skin is often red and hot to the touch and the hallmark sign is the lack of sweat production. Treatment must begin immediately to cool the body with whatever is available from ice packs to lower extremity emergence in running water. This fatal complication of an imbalance in heat homeostasis is best treated by trained medical personnel if at all possible. Prevention, as usual, is the key here and in these illnesses is rather simple. Firstly, get in shape. Consult your physician before beginning an exercise program and then begin a graded exercise program. While with your doctor, review your medications to help ascertain your risk. It also helps to gradually increase your exposure to hot and humid environments before your hunt if at all possible to help you acclimatize quicker when you go on your adventure. Essential and simplest of all, is to stay well hydrated. An easy rule is that if you are in a hot and humid environment and your urine is more yellow than clear, you need more fluids and you are at increased risk for heat related illness. Also, wear moisture wicking clothing which means avoid cotton clothes and take frequent breaks to cool off. As usual, enjoy the outdoors and be safe!