There are 14 documented disorders which can be due to excess exposure to heat. Some of the common and important disorders are discussed below:
Effects of Heat:
Heat stroke
Heat stroke Also known as sunstroke. This is due to failure of heat regulating mechanism of human body. The main feature of heat stroke is very high body temperature of about 110 degree Fahrenheit(430 Centigrade). High temperature is accompanied by convulsion, delirium and partial or complete loss of consciousness. Skin is usually dry and hot. Sweating is absent or very scanty. Death rate is high (about 40%) even it quick medical attention is provided. Treatment of heat stroke consists of rapidly cooling the body in ice water till rectal temperature falls blow 102 degree Fahrenheit. Rectal temperature should be continuously monitored. It indicate the progress of treatment as well as guard against hypothermia, that may occur if cooling is continued for very long . Further treatment of heat stroke is supportive & symptomatic. The patient should be hospitalized for several days, till temperature control & regulatory mechanism become stable.
Heat Hyperpyrexia
This is due to impairment of heat regulating mechanism of human body. It generally have temperature above 106 degree Fahrenheit. It may be seen before heat stroke /sun stroke.
Heat exhaustion
It is not because of failure of heat regulating mechanism ,unlike heat stroke and heat hyperpyrexia. It is less severe than heat stroke and due to imbalance or inadequate replacement of water and salts lost by perspiration due to excess heat. Body temperature may be normal or slightly higher but generally do not cross 102 degree Fahrenheit. It is seen after several days of high temperature. Symptoms of heat exhaustion are dizziness, weakness, and fatigue. Elderly people with heat exhaustion may require hospitalization. Treatment is correction of fluid and electrolyte imbalance.
Heat cramps
It is seen in people engaged in heavy work and muscular activity at high temperature and humidity, mainly those who are not adopted to muscular activities at high temperature and humidity. Heat cramp is due to loss of sodium and chlorides in blood and it causes painful and spasmodic contraction of skeletal muscles.
Heat syncope
Heat syncope is quite common problem . In typical form of heat syncope, person standing in sun suddenly become pale, his blood pressure falls and he collapses. Body temperature is normal. This is due to pooling of blood in legs due to dilatation of blood vessels in legs. This results in reduced venous return to heart and fall in blood pressure and lack of blood supply in brain. The treatment is very simple. The patient is made to lie down in shade with the head slightly down. Patient recovers in 5 to 10 minutes. This type of problem is very common in soldiers standing in sun for parade.
Preventive Measures
The effects of heat can be prevented by following measures.
Replacement of water
People working under high temperature and humidity should encouraged to drink lots of cool water. In hot climate a person requires about one liter of water per hour during physical work and a sedentary worker need half liter of water. There is no need of extra salt in water because sweat contain very less salt, contrary to popular belief that extra salt is required. But if a person is not acclimatized he should take extra salt for first 10 days.
Clothing
The cloth used should be loose fitting and of light color
Regulation of work
Duration of work at hot and humid condition should be reduced. There should be periods of rest in between intense work. If symptoms of effect of heat like headache, dizziness appear the worker should be removed to a cooler place and adequate treatment given.
Protective Devices
protective goggles, helmets and shields should be used where practicable.
