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Heat Emergencies

Knowing what to do if a medical emergency strikes takes on added impact for sailors going offshore and outside of range of a 911 dial tone. In this new regular column, Physician’s Assistant Bill Mahaffy, a practitioner in emergency medicine and a lifelong sailor, will present medical guidance toward health concerns and emergencies that may occur on board.

HEAT EMERGENCIES: How to recognize the signs and what to do if your crew is stricken

As we sail through the summer months, cruise in warm climes, or passage into equatorial regions, it’s important to realize the potential threat of two much heat. The body can release surplus heat through convection and conduction (a breeze passes over the body to carry the heat away; the surrounding environment is cooler than the body temperature such as immersion in cool water). Additionally, as the ambient temperature increases, the body lowers heat through the evaporation of sweat. Unfortunately, this method has its limitations and effective sweat evaporation can only occur with a relative humidity of less than about 75 percent.

If the exposure is long and intense enough, heat illness will eventually affect everyone, with the very young and the elderly at greatest risk because of their inability to mount sufficient heat loss responses. There are three basic categories of heat illness with increasing severity.

Pains begin in the legs, abdomen or both. This condition usually occurs secondary to profuse sweating, associated with loss of sodium (salt). Despite adequate fluid intake, inadequate salt engenders the condition, or hyponatremia.The cramps may be mild at first but can progress to severe pain and may be accompanied by nausea.

First, move the patient to a cool environment. If there is no nausea, give the patient a salt-containing solution (Gatorade or similar electrolyte containing drink is best) and have them sip slowly. DO NOT GIVE SALT TABLETS, which can worsen nausea. As the patient begins to feel better, he may want to resume his previous activities, but should be strongly discouraged.

Heat exhaustion is characterized by headache, fatigue, dizziness, nausea and possibly abdominal cramps, disorientation, profuse sweating and cool, clammy skin. Occurring from fluid and salt loss and peripheral blood pooling, the body temperature may be low, normal or slightly elevated. The stricken should be moved to a cooler environment, clothes loosened, placed on his back with legs slightly elevated. Fan and sponge the patient, but do not cool the patient quickly (as in heat stroke) because rapid cooling may actually make things worse. Since the patient is frequently nauseated, do not give fluids, though a few sips of Gatorade can be tried. If you are able to get back to the dock, do so. If offshore, a course alteration to the nearest port is required.

Heat stroke is the most serious and potentially lethal form of heat illness. The Classic form of heat stroke typically affects the very young, the old and/or debilitated but can affect anyone. It is indicated by initial profuse sweating Then, for a variety of reasons, the stricken soon becomes dehydrated and loses the ability to sweat. At this point they become dehydrated and their internal temp will sky-rocket. The symptoms of heat stroke are: 1) Hot, flushed skin which may be dry. 2) Elevated body temp (usually 105 F or higher). 3) Confusion or possibly unconsciousness. 4) Rapid breathing. 5) Rapid pulse that is hard to feel.

A second form, Exertional heat stroke is caused when the body is still capable of sweating but the environment limits the effective cooling, or relative humidity that is more than 60-65%. Dehydration is usually not as much of a component and therefore the mortality rate, while still significant, is much lower (about 20%).

Heat stroke, regardless of the type, is a true medical emergency. The mortality rate for classic heat stroke can approach 70 percent. On board, get the patient into some shade and pour water over their body. I have heard of one instance where the crew filled the cockpit with water and the block ice from the icebox and immersed the patient in this tub. Fanning, which maximizes both the conduction and convection methods of heat loss, should also be done.The treatment goal is to maintain airway, breathing and circulation while lowering the body temperature as quickly as possible. Rehydration is also very important but this is best accomplished with intravenous fluids. Rapid access to medical care is also essential to improve chances for survival and limit potential neurological damage.

Heat illness can become a significant problem in the marine environment. Few small sailboats have air-conditioning and it is nearly impossible to escape from a hot, humid, windless day. Obviously, prevention is the best treatment. Have plenty of fluids available and encourage adequate intake (Do not include beer as a fluid—alcohol will actually worsen the patient’s condition). Be particularly aware of crew members taking medications for high blood pressure as they are far more susceptible to heat illness. Finally, recognize the early signs of heat illness and begin prompt treatment.

William Mahaffy is offline  
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