Heat

The human being suffers a variety of reactions when exposed to high temperatures.  Usually there are three different forms of this reaction. They are called "heat cramps," "heat exhaustion" and "heat stroke." They may occur during exposure to the heat from the sun in climates where the sun is especially hot, and they occur particularly to people who have not been acclimated by exposure to the sun gradually over a long period of time. After a while the body accustoms itself to heat by a decline in the amount of sodium in the perspiration.

Heat Cramps

Heat cramps occur in those who have sweated excessively and taken excessive amounts of water. The condition usually occurs in stokers and miners. Chief among the symptoms is pain which is due to a spasm of the muscles of the body. The taking of dilute salt solution instead of water for drinking purposes prevents heat cramp with certainty.

Heat Exhaustion

Heat exhaustion comes usually during excessively hot weather and is accompanied by changes in the circulation of the blood. The chief symptom of heat exhaustion is weakness and faintness which may go on to the coming of actual unconsciousness. The sweating is profuse, but the temperature of the body does not change.

It is easy to prevent heat exhaustion by reducing the amount of physical activity during excessively hot weather and by regulating the atmosphere by the use of electric fans or other similar devices. Whenever anyone is exposed to excessive sweating during the hot weather, dilute salt solutions should be taken instead of ordinary drinking water.

Heatstroke Or Sunstroke

The chief manifestations of heat stroke or sunstroke include rapidly mounting fever and a dry skin. Under such conditions the temperature of the body may go as high as 110 or even 112. With these high temperatures comes apathy and, finally, the person becomes unconscious. Apparently this disorder is more common in old people and in alcoholics. Heat stroke is also fairly frequent during the first few days of a heat wave when people keep right on working hard without regard to the height of the temperature. The condition occurs more often with a high humidity than when there is low humidity. The recommendation has been made that hospitals keep available tubs filled with water and ice, so that persons with heat stroke may be cooled off as rapidly as possible by being immersed in cold water and given massage to promote circulation of the blood at the same time. Just as soon as the high temperature is brought down to 100 degrees, the person is put in bed and the temperature is controlled by the use of wet sheets and an electric fan. The purpose of this is to stop as rapidly as possible the effects of the heat on the vital organs of .the body. Under such circumstances everything possible is done to keep the heart and circulation of the patient in working condition.

Cold - Frostbite

Experts say that cold was the most important disabling condition encountered by military personnel in World War II. In the British army alone there were almost 85,000 cases of frostbite. In the fighting in Korea, exposure to wet and dry cold was the most serious condition confronting the doctors who had to keep patients or soldiers in condition to carry on their work. The human being can withstand extreme cold as low as 50 degrees below zero, with proper clothing and proper nutrition. The greatest danger comes from exposure to cold without adequate protection. When the body is exposed to cold, the first defense is for the blood vessels in the skin to become constricted so that there is a fall in the skin temperature without much change in the temperature inside the body. One does not experience discomfort from extreme cold in the fingers and toes until their temperature hits about 60 degrees Fahrenheit from a normal of 80 to 85 degrees Fahrenheit for this portion of the body. There is great discomfort when the temperature of the shoulders, back, or legs drops below 80 degrees Fahrenheit from a normal of 90 to 95. The body responds with intermittent shivering in an attempt to raise the temperature. Even the warmest clothing will not protect the wearer in temperatures below the freezing point unless there is exercise. Fingers and toes suffer from cold more than any other part of the body, first becoming painful, then numb and finally frostbitten. The disappearance of pain is a warning sign of great danger.

Not long ago an attempt was made to control certain difficult and uncontrollable diseases by causing the person to be kept in extreme cold. One patient with cancer survived a body temperature of 74°F. under these circumstances. On the other hand, flyers who fell into cold water in the Arctic, where the temperature of the water was between 41 and 50 degrees, have died in less than thirty minutes. When, however, the water temperature was 68 degrees, the flyers survived for several hours. In the German prison camps extensive chilling experiments were carried out on human beings. Consciousness was lost when the temperature in the interior of the body fell to 86 degrees. It took from seventy to ninety minutes' exposure to extremely low temperatures to reach a temperature inside the body of 86 degrees. The Germans report that death occurred when the temperature of the inside of the body was between 78 and 86 after exposures of one to two hours. The most effective treatment of freezing is rapid rewarming.

Dr. Tinsley Harrison says that chilling drafts and sudden temperature changes are more important than cold itself, because they predispose to disease by lowering resistance to infection. Local chilling may produce nerve pains, muscle pains, sore throat, bronchitis, or pneumonia when resistance is lowered and the germs infect.

Compression

The chief effects of high altitude and changes in barometric pressure are dependent on the way in which this affects the use of oxygen by the body. The most common symptoms associated with compression, as in diving or descending suddenly from high altitudes, is pain in one or both ears, particularly when the tubes are obstructed. To this the name of aero-otitis media has been given. After or during the breathing of oxygen this condition may develop during sleep, because the Eustachian tubes, which go from the back of the throat to the middle ear, rarely open during sleep. The rate of compression is important in governing the degree to which an individual suffers from high altitude. If descent is made reasonably slowly, the difficulties do not arise. In  commercial passenger aircraft the rate of descent from high altitude is limited to 300 feet per minute. Under these circumstances pain in the ears seldom occurs. Sometimes people who have been exposed to compression develop pains in the frontal sinuses because of blocking. The pain is due to the same conditions that result in pain in the ears.

A remarkable condition is the expansion of abdominal gas that occurs under some circumstances. When helium was used in diving, the mouthpiece produced flow of saliva and considerable amounts of gas were swallowed. When the men came to the surface rapidly, the gas in the stomach expanded and the pressure brought about so much pain as to induce collapse. Now it is generally known that swallowed air or gas, rather than food, is the source of most abdominal gas. Certain foods, however. tend to produce abdominal gas. including melons, beans, and carbonated beverages.

The big problem of high altitudes is little oxygen and this, of course, is being governed in aircraft by the use of oxygen chambers, so that oxygen is then released into the cabins and the pressure is kept at a proper level. Nowadays provision is made for a supply of oxygen on all flights above 10,000 feet and on all flights of more than four hours’ duration between 8.000 and 10,000 feet.

When divers and compressed-air workers are subjected to rapid decompression, air bubbles form in the blood and they may produce such symptoms as pains which are called "the bends," asphyxiation  which is called "the chokes." and paralysis. The most common manifestation is the dull, throbbing type of pain in the joints and in the muscles and bones which is known as "the bends." Normal breathing becomes shallow and rapid and then the worker seems short of breath. This condition is called "the chokes." If this is not relieved. the skin becomes cold and moist. the circulation impaired. and the person may actually have symptoms like those of shock. The treatment includes prolonged recompression and the use of oxygen and fluids, and then slow decompressions o that the worker does not suffer from these difficult symptoms. The condition is a serious one and should always be recognized and treated promptly.

Radiation

People are continually exposed to minute amounts of radiation that come not only from the various forces in the atmosphere surrounding  the world but also from naturally radioactive materials that occur in soil and water and in other materials in our environment. Fortunately this radiation is so small in amount that it does not seem to have any significant effect on the body. Also a certain amount of radiation may come from X-ray tubes or from radium or from the taking of various radioactive isotopes. There is no way in which an untrained person can find out whether or not he is being subjected to radiation. For that reason, various means have been developed for determining the presence of radiation in our atmosphere. These include the exposure of photographic film and devices like the Geiger counter.

The physicists have classified the radiation into various types of waves and particles which vary greatly in their effects on the living tissue of the body. Some rays penetrate more than do others. The irradiation affects the protoplasm of the tissues and brings about certain chemical and physical effects. Some cells of the body are more sensitive to radiation than are others. When radiation is used against tumors, the physician knows the sensitivity of the cells to the radiation and the extent to which it can be counted on to stop cellular growth.

Radiation sickness results from absorption of the products of disintegration of the protein of the body. The chief symptom of radiation sickness is mild to severe nausea and, in some instances, there may be diarrhea due to the response of the intestinal tissues to the irritation.

Another type of radiation sickness results from irradiation of the entire body over a short period of time. This begins suddenly with severe illness that may go to the point of prostration. There may be there after a phase of relative well-being, followed by severe illness and ultimately by death.

The most sensitive cells of the body are the white blood cells of the blood. Radiation can damage the blood-forming organs so that the cells fall below normal with subsequent hemorrhage due to destruction of the thrombocytes in the blood and increased permeability of the capillaries from damage to the cells. Obviously, with loss of blood comes severe anemia. The effects of radiation can be such as to produce sterility, but permanent sterility is not expected from irradiation because the dose necessary to sterilize the male sex gland is close to what is a fatal dose. In the woman also the radiation may produce transient sterility; permanent sterility is rare.

At present the best method of treatment for irradiation is the transfusion of whole blood, the use of antibiotic drugs to control infection, and forced nutrition to enable the body to overcome the damage that has occurred.