injuries and poisoning
Overview of Heat Disorders
Causes of Heat Disorders
Heat disorders are caused by excessive heat production, ineffective heat loss, or both. Excessive heat productioncan be caused by the following: Infections that cause fever Hyperthyroidism , which speeds up the body’s metabolism Strenuous muscle activity, which may occur during exercise or physical labor (particularly among obese people) or can result from disorders such as , agitation, or Certain stimulant drugs, such as Cocaine , , because Aspirin Poisoning cause cells to produce excessive heat Ineffective heat lossis most common in hot, humid conditions. The following also greatly interfere with heat loss: Heavy, tight, clothing that does not breathe (that is, does not allow air and moisture to pass through easily). Wearing such clothing prevents sweat from evaporating from the skin surface and cooling the body. Certain medications, most often antipsychotic drugs and those with Anticholinergic: What Does It Mean? , may reduce sweating. Certain disorders that affect the skin interfere with sweating. These disorders include , Obesity interferes with heat loss because a thick layer of fat is a good insulator. Mental states that interfere with sensible responses to heat. For example, older people with dementia and intoxicated people who are in a hot environment may not move to a cool environment, remove heavy clothing, or turn on an air conditioner. The chance of developing heat disorders increases when exposure to heat occurs suddenly, such as when a child is left in a closed car on a hot summer day. In hot weather, the interior temperature of a closed car can rise from 80 to 120° F (27 to 49° C) in as little as 15 minutes. When people are gradually exposed to longer periods of heat and humidity, the body adjusts and is better able to maintain normal body temperature. This process is called acclimatization. Acclimatization occurs more rapidly in young or physically active people than in older or physically inactive people. Factors that increase vulnerability to the effects of most heat disorders include the following: Being very old or very young Having certain medical conditions, such as those that involve malfunction of the heart, lungs, kidneys, or liver Taking diuretics Having imbalances in blood chemistries (electrolytes) Being dehydrated There are several reasons why older people have particular difficulty when the temperature is high: They are not as able as younger people to gradually adjust (acclimate) to long periods of high temperatures and humidity. They tend to have difficulty increasing the flow of blood to all skin surfaces because of reduced circulation, and thus their body does not cool itself as readily. They tend to lose sweat glands with age. They have delayed perception of heat and are, therefore, slow to respond to temperature change. They may have mobility problems that make it difficult for them to move out of hot environments. Certain disorders that are more common among older people, such as heart and kidney failure, can interfere with the body’s ability to cool itself. People with high blood pressure are often on low-salt diets, which may prevent them from consuming enough salt to replace the salt they lose in sweat. Aging also affects thirst. Older people do not get thirsty as readily as younger people. Thus, older people tend to get dehydrated, which in turn means they are less able to sweat in warm surroundings. 