McKenzie and LeCount have noted the following autopsy findings: Generalized passive hyperaemia of brain and lungs, oedema of brain and lungs as well as petechial haemorrhages of various mucous membranes and the skin.
Susceptibility to Heat Stroke.—As a matter of fact in a body of men exposed to identical conditions of heat of sun and relative humidity we note certain cases exhibiting typical heat stroke while other men will only show evidences of heat prostration.
Alcoholism, obesity, diseases of heart and lungs, overcrowding, muscular fatigue, insufficient circulation of air, with the wet bulb about 90°F., and not drinking a sufficient amount of water, predispose to heat injury.
It must always be kept in mind that the hyperpyrexial type of malignant tertian malaria may give a clinical picture of heat stroke.
Fiske has noted that in oil-burning firerooms, even with a temperature of 140°F., 10° higher than on similar ships burning coal, there were no cases of heat prostration. He attributes this to the less fatiguing work in tending oil-burning furnaces and the smaller number of men required, this reducing overcrowding.
Symptomatology
In heat stroke there are usually prodromata of dizziness, dry skin, headache, and somnolence, following which the body temperature shoots up to 105°F. or even above 110°F. There is a desire for frequent micturition, which may be considered as a prodromal warning of embarrassment of the sweating function. The skin is hot and dry and the pupils may be contracted. The pulse which is at first full and rapid, soon becomes irregular. There may be delirium or coma or convulsive seizures. The patient is unconscious with irregular or Cheyne-Stokes respiration.
Hiller divides these cases into (1) those showing an asphyxia syndrome, as characterized by cyanosis and collapse, with cessation of respiration and enfeebled circulation. Prolonged artificial respiration is required in such cases. (2) A paralytic type with deep coma, recurring convulsions and extreme hyperpyrexia. These cases exhibit oedema of lungs and brain and necessitate venesection. (3) A psychopathic type in which there is delirium often of a violent type with delusions of persecution. Such cases often commit suicide.
In heat prostration we have giddiness and possibly nausea with pale face, often bathed in cold perspiration and dilated pupils. The pulse is very weak and syncope may ensue. The temperature is not elevated and may be subnormal. Rarely the temperature is slightly elevated. The respiration is shallow and sighing. Headache is often complained of after recovery. Following this or the more dangerous heat stroke we may have lack of mental concentration or loss of memory with recurring headache upon even moderate exposure to the sun.