Discuss the clinical condition that occur after exposure to excessive heat.
1. Heat cramps:
They are caused by a rapid dehydration of body through the
loss of water and salt in the sweat. It is seen in workers in high temperature
when sweating has been profuse. The onset is usually sudden. Severe &
painful paroxysmal cramps affecting the muscles of the arms, legs and.
abdomen occur. The face is
flushed, the pupils dilated and the patient complains of dizziness, tinnitus,
headache and vomiting. Intravenous injecting of saling gives rapid relief.
2. Heat prostration: (Heat
exhaustion/heat syncope/heat collapse)
It
is a condition of collapse without increase in body temperature, which follows
exposure to excessive heat. It is precipitated by muscular work and unsuitable
clothing. There is exterme exhaustion and peripheral vascular collapse. The
patient feels suddenly weak, giddy and sick. He may stagger or fall. The face
is pale, the skin cold, the temperature subnormal. The pupils are dilated, the
pulse small and thready and the respiration sighing. The patient usually
recovers if placed at rest, but death may take place from heart failure.
3. Heat hyperpyrexia/Heat
stroke:
It
is a condition characterized by rectal temperature greater than 410C
and neurological disturbances, such as psychosis, delirium, stupor, coma and
convulsions. The term thermic fever or “sunstroke” is used when there has been
direct exposure to the sun. High temperature, increased humidity, minor
infections, muscular activity and lack of acclimastication are the principal
factors in the initiation. Where there is 100% humidity, a temperature of 320C
in the environment may lead to heat stroke. Other factors are old age,
preexisting disease, alcoholism, use of major tranquillisers, obesity, lack of
air movement and unsuitable clothing. Failure of cutaneous blood flow and
sweating, the factors which control body temperature, leads to a breakdown of
the heat regulating centre of the hypothalamus. Heat stroke occurs:
- In young persons exposed to high temperature while undergoing severe exertion.
- In old persons usually over 60 years during heat waves.
Flash burn
& crocodile burn in electrocution.
Ans.
§
Flash/Spark burn: The intense heat
which may result from flash-over produces burns, which resemble thermal burns.
In spark burn, there is an air gap between metal and skin.
§
Here a central nodule of fused keratin brown or
yellow in colour is surrounded by the typical areola of pale skin.
§
The burns may be as small as pinpoints, or
deeply seated an contracted if contact is prolonged or very high voltage is
applied.
§
If the area of contact is relatively large, e.g.
when a hot wire is grasped with a wet hand.
