Each year there are many people who get sick or die due to overexposure to heat. In 2001, a professional football player Korey Stringer died of heat stroke during a Minnesota Vikings training camp, and Steve Bechler major league baseball player for the Baltimore Oriels also died for heat stroke. The heat wave that hit Europe in 2003 caused more than 70,000 deaths.
Patients often present to the urgent care for heat related illness, and with the rising temperatures of summer approaching I think it’s important to discuss the topic of heat illness.
Heat exhaustion is common and most of us have experienced this at least once in our lives. It can occur when the core body temperature rises greater than 98.6 degrees the patient may have some or all of the symptoms including:
- Rapid heart rate
- Nausea and vomiting
- Fainting with rapid return of normal mental status
- Severe thirst
- Signs of mild to moderate dehydration
Not all of these signs need to be present to diagnose heat exhaustion.
Understanding the signs and symptoms of heat stroke (note this is different from heat exhaustion described above) is important to help prevent this potentially life threatening illness. When the patient’s core temperature reaches 104 degrees F or higher, then may begin to have an altered mental status and have symptoms of confusion. They may or may not have sweating (the lack of sweating is a late sign of heat stroke – DO NOT WAIT FOR LACK OF SWEATING TO TREAT FOR HEAT ILLNESS). They might also complain of flu-like symptoms and have a rapid heart rate and low blood pressure. Heat illness patients may have have difficulty with balance, confusion and the late signs of heat illness may be seizures, coma or an abnormal heart rate called ventricular fibrillation. Heat stroke is more common in environments with high temperatures and when the patient is exercising out in the heat without drinking enough fluids. It may be worse in a humid climate.
Studies done on runners have shown that dehydration alone is capable of elevating body temperatures, so preventing dehydration is very important in reducing risks of heat related illness.
**Heat exhaustion and heat stroke are probably a continuum of heat disorders rather than distinct pathophysiologic entities. In the setting of heat illness, patients with dizziness, decreased mental status, confusion, headache, or balance problems should be treated for heat stroke.
Prevention of heat stroke: If the patient is an athlete or will be doing vigorous physical activity, it is important to acclimatize for 8-12 days prior to exercise. The military uses this technique with soldiers prior to sending them to Iraq where the cycle on exercise bikes in a sauna. With acclimatization, sweating will start earlier and there will be an increased rate of sweating and decreased loss of salts.
97% of cooling occurs at the skin/air interface which functions similar to the radiator of your car. Dilation of blood vessels at the surface of the skin allows more heat loss and evaporation on the skin also increases the rate of heat loss.
It’s also important to help decrease temperatures earlier if you develop symptoms of heat exhaustion so that this does not progress to heat stroke. Getting out of the direct sunlight, increasing fluid intake, and increasing evaporative cooling can all be helpful. Since vasoconstriction happens when spraying the skin with cold water, it may be more efficient to help with evaporative cooling by spraying room temperature water on the skin to help prevent the blood vessels in the skin from constricting and keeping the process of vasoconstriction from occurring.
Risk factors for heat exhaustion or heat stroke may include:
- Elderly patients because they may have decreased heart function. To maintain their blood pressure, than may actually constrict their blood vessels (rather than dilate their blood vessels) which may worsen heat illness.
- Medications such as beta-blockers because they do not allow the heart rate to increase. Also anticholinergic medications that decrease sweating can make it harder to sweat and thus lead to increased temperatures. Diuretics may predispose to dehydration
- Exercising in very hot/humid temperatures
- People who are not acclimatized to hot temperatures
- The use of illicit drugs such as methamphetamines may decrease the ability to sweat and increase the generation of heat production.
- Neonates lack thermoregulatory and sweating capabilities
- Obese individuals have more insulation and less surface-area-to volume ration with which to dissipate heat
- Hyperthyroidism increases metabolic rate and that can lead to increase heat production
- Dermatology disorders over large skin areas such as burns can decrease the ability to sweat and lead to decreased cooling abilities
Treatment of Heat Stroke: Rapid cooling is the most important treatment. Get the heat stroke victim out of direct sunlight and to a cool area if possible. Using ice bags in the arm pits, groin and against the skin of the neck can be helpful for cooling. The goal should not be to cause the victim to shiver because shivering actually causes warming. IV fluids may also be helpful but are secondary to rapid cooling.
This document is for informational purposes only, and should not be considered medical advice for any individual patient. If you have questions please contact your medical provider.
I hope that you have found this information useful. Wishing you the best of health,
Scott Rennie, DO