Injuries Due To Extremes Of Temperature And Pressure

Injuries due to extremes of temperature and pressure Dr. Mehzabin Ahmed

Thermal Injuries

 

• Exposure to excessive boiling or burning substances causes • Burn Injuries

• Exposure to excessive ambient temperatures causes                                                                                               • Heat exhaustion • Heat cramps • Heat stroke

• Exposure to excessive electrical currents causes • Electrical burns

Thermal Injuries • Partial-thickness burns include epidermis and superficial part of the dermis. In partial-thickness burns, the deeper portions of the dermal appendages are spared. – First-degree burns (epithelial involvement only) – Second-degree burns (both epidermis and superficial dermis)

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Full-thickness burn involves total destruction of the epidermis and dermis, with loss of the dermal appendages that would have provided cells for epithelial regeneration. – Third- degree burns (all the layers of the skin extending to the subcutaneous fat) – Fourth-degree burns ( all the layers of the skin extending to the underlying muscle and bone).

Common complications of burn injuries: •

Hypovolemic shock due to loss of fluids

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Injury to airways and lungs due to toxic substances in smoke

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Secondary infection in the open wounds

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Hypermetabolic state with excessive heat loss and increased need for nutritional support

Hyperthermia •

Heat cramps result from loss of electrolytes through sweating. Cramping of voluntary muscles, usually in association with vigorous exercise, is the hallmark.

•Heat exhaustion is probably the most common heat syndrome. Its onset is sudden, with prostration and collapse, and it results from a failure of the cardiovascular system to compensate for hypovolemia, secondary to water depletion.

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Heat stroke is associated with high ambient temperatures and high humidity. Thermoregulatory mechanisms fail, sweating ceases, and core body temperature rises.

Hypothermia. • Frostnip – the term is used for reversible injury due to subfreezing conditions. Firm cold white areas appear on the face, ears and extremities, which peel or blister in 24 to 72 hours. • Immersion (trench) foot - the term is used for injury due to prolonged exposure to wet cold at temperatures above freezing. Immersion foot can be prevented by changing socks frequently and keeping the feet and boots dry • Frostbite - it involves exposed areas like fingers, hands, toes, ears, nose and cheeks. Severe frostbite can result in blisters or ulcer formation. As the frostbite progresses lack of blood supply causes tissue death and gangrene may occur

Electrical Injuries • The thermal effects of the passage of the electric current depend on its intensity. High-intensity current, such as lightning coursing along the skin, produces linear arborizing burns known as lightning marks. • Sometimes intense current is conducted around the victim (so-called flashover), blasting and disrupting the clothing but doing little injury. • When lightning is transmitted internally, it may produce sufficient heat and steam to explode solid organs, fracture bones, or char areas of organs.

Injuries due to sudden decrease in Atmospheric Pressure • High altitude illness is encountered in mountain climbers in the rarefied atmosphere of altitudes above 4000 m. • The lowered oxygen tension produces progressive mental disorientation and may be accompanied by pulmonary edema.

Injuries due to sudden decrease in Atmospheric Pressure •Decompression (Caisson) disease is seen when people spend time at increased atmospheric pressure and return to lower pressures too rapidly. Dissolved gases come out of solution and form minute bubbles in the blood and tissues. •Gas embolism may occur as a complication of scuba diving, mechanical positive-pressure ventilation, and hyperbaric oxygen therapy.

Injuries due sudden increase in Atmospheric Pressure • Blast Injury. This form of injury obviously implies a violent increase in pressure either in the atmosphere (air blast) or in water (immersion blast). • With air blast, the compression wave impinges on the side toward the explosion and so may collapse the thorax or violently compress the abdomen, with rupture of internal organs. • In immersion blast, the pressure is supplied to the body from all sides, inducing injuries similar to those of air blast

Common Blast Injuries