AHEAD OF THE MONSOON, the prevailing hot weather conditions in Assam and other parts of the North East have hit people hard. Heat exhaustion can occur if someone has been exposed to high temperatures for several days and have become dehydrated. Heat exhaustion is strongly related to the heat index � a measurement of how hot one feels when the effects of relative humidity and air temperature are combined. A relative humidity of 60 per cent or more hampers sweat evaporation, which hinders our body�s ability to cool itself. The risk of heat-related illness dramatically increases when the heat index climbs to 32 degrees or more. So it is important, especially during heat waves, to remember that the heat index is even higher when one is standing in full sunshine. One may be especially prone to develop heat exhaustion during a prolonged heat wave, particularly if there are stagnant atmospheric conditions and poor air quality. In what is known as the �heat island effect�, asphalt and concrete store heat during the day and gradually release it at night, resulting in higher night-time temperatures.
There are two types of heat exhaustion:
l Water depletion: A person may suffer from excessive thirst, weakness, headache and loss of consciousness.
l Salt depletion: Signs include nausea and vomiting, frequent muscle cramps and dizziness.
Although heat exhaustion is not as serious as heat stroke, it is not to be taken lightly. Without proper intervention, heat exhaustion can progress to heat stroke, which can damage the brain and other vital organs, and even cause death. Heat cramps: Painful cramps of the abdominal muscles, arms, or legs.
What is dehydration?
More than 75 per cent of our body weight is water. Water is essential for our metabolism, the way our bodies function. Technically, dehydration sets in when a person has lost 2 per cent of his or her body weight. How quickly that happens depends mainly on the conditions. It�s especially dangerous for infants and young children, the elderly and people with chronic medical conditions to become dehydrated. Dehydration occurs when the amount of water leaving the body is greater than the amount taken in. Dehydration can be a serious heat-related disease, as well as being a dangerous side effect of diarrhoea, vomiting, and fever. Children and persons over the age of 60 are particularly susceptible to dehydration. Untreated dehydration can lead to three worse types of heat illness.
What puts one at risk of dehydration?
Prolonged exposure to high temperatures, direct sun and high humidity, without sufficient rest and fluids puts one at risk of dehydration. A child is at more risk as the child�s body surface area makes up a much greater proportion of his overall weight than that of an adult, which means children face much greater risk of dehydration and heat-related illness. Infants and children up to age 4, and adults over age 65, are particularly vulnerable because they adjust to heat more slowly than other people. Certain health conditions which include heart, lung, kidney disease, obesity or underweight, high blood pressure, diabetes, mental illness, sickle cell trait, alcoholism, sunburn, and any conditions that cause fever can cause heat stroke. People with diabetes are at increased risk of heat-related illness. People who are taking medications like diuretics, sedatives, tranquillisers, stimulants, some heart and blood pressure medications, and medications for psychiatric conditions are at more risk to suffer from heat stroke.
How can dehydration be prevented?
We can prevent dehydration by drinking plenty of fluids, especially when working or playing in the sun. We have to make sure that we are taking in more fluid than we are losing. We can try to schedule physical outdoor activities for the cooler parts of the day. We can drink appropriate sports drinks to help maintain electrolyte balance.
Treatment for dehydration:
If caught early, dehydration can often be treated at home. In children, directions for giving food and fluids will differ according to the cause of the dehydration, so it is important to consult the child�s doctor. In cases of mild dehydration, simple rehydration is recommended by drinking fluids. Many sports drinks on the market effectively restore body fluids, electrolytes, and salt balance. For moderate dehydration, intravenous (IV) fluids may be required, although, if caught early enough, simple rehydration may be effective. Cases of serious dehydration should be treated as a medical emergency, and hospitalisation, along with intravenous fluids, is necessary. Immediate action should be taken.
Signs of heat exhaustion to watch out for:
The most common signs and symptoms of heat exhaustion include: confusion, dark-coloured urine (a sign of dehydration), dizziness, fainting, fatigue, headache, muscle cramps, nausea, pale skin, profuse sweating and rapid heartbeat. Thirst doesn�t really kick in until someone has lost 2 per cent of his or her body weight as sweat.
Heat stroke: Heat stroke is the most severe form of heat illness and is a life-threatening emergency. It is the result of long, extreme exposure to the sun, in which a person does not sweat enough to lower body temperature. The elderly, infants, persons who work outdoors, people with mental illness, obesity, poor circulation, and those on certain types of medications or drinking alcohol are most susceptible to heat stroke. It is a condition that develops rapidly and requires immediate medical treatment. A temperature of 40 degree Centigrade or higher and severe symptoms, including nausea and vomiting, seizures, disorientation or delirium, lack of sweating, shortness of breath, unconsciousness, and coma can occur in heat stroke.
What causes heat stroke?
Our bodies produce a tremendous amount of internal heat and we normally cool ourselves by sweating and radiating heat through the skin. However, in certain circumstances, such as extreme heat, high humidity, or vigorous activity in the hot sun, this cooling system may begin to fail, allowing heat to build up to dangerous levels. If a person becomes dehydrated and cannot sweat enough to cool their body, their internal temperature may rise to dangerously high levels, causing heat stroke.
Symptoms of heat stroke:
Each individual may experience symptoms differently. Symptoms may include headache, dizziness, disorientation, agitation or confusion, sluggishness or fatigue, seizure, hot and dry skin that is flushed but not sweaty, high body temperature, loss of consciousness, rapid heart beat, hallucinations. The symptoms of a heat stroke may resemble other medical conditions or problems. Therefore, a doctor should always be consulted.
Treatment for heat exhaustion and heat stroke:
Both heat exhaustion and heat stroke require immediate care. Heat stroke is a medical emergency that, when untreated, can be deadly. Any child with heat stroke should be rushed to the nearest hospital. If anyone has symptoms of heat exhaustion, it is essential to immediately get out of the heat and rest, preferably in an air-conditioned room or try to find the nearest cool and shady place.
It is important for the person to be treated immediately as heat stroke can cause permanent damage or death.
Some immediate first-aid measures:
One can take these measures while waiting for help to arrive, including the following � get the person to a shaded area, remove clothing and gently apply cool water to the skin followed by fanning to stimulate sweating, apply ice packs to the groin and armpits, have the person lie down in a cool area with their feet slightly elevated, cool the person rapidly however one can.
Intravenous (IV) fluids are often necessary to compensate for fluid or electrolyte loss. Bed rest is generally advised and body temperature may fluctuate abnormally for weeks after heat stroke.
So, next time you go out in the sun, make sure you drink plenty of water early and often. Avoid caffeinated tea, coffee, soda and alcohol, as these can lead to dehydration. Wear lightweight, tightly woven, loose-fitting clothing in light colours. Schedule vigorous activity and sports for cooler times of the day. Protect yourself from the sun by wearing a hat, sunglasses and using an umbrella. Never leave children or pets in closed cars on warm or sunny days. Ask children out to practice or play fully hydrated. Then, during play, make sure the children take regular breaks to drink fluids, even if the child isn�t thirsty. By taking these simple measures you can beat the heat.
(The writer is Senior Consultant Cardiac Surgeon, Health City Hospital, Guwahati)