injuries poisoning
Decompression Sickness
Introduction
Decompression sickness occurs when rapid pressure reduction (eg, during ascent from a dive, exit from a caisson or hyperbaric chamber, or ascent to altitude) causes gas previously dissolved in blood or tissues to form bubbles in blood vessels. Symptoms typically include pain, neurologic symptoms, or both. Severe cases can be fatal. Diagnosis is clinical. Definitive treatment is Recompression Therapy . Proper diving techniques are essential for prevention. (See also Overview of Diving Injuries .) Henry’s law states that the quantity of gas dissolved in a liquid is directly proportional to the partial pressure of the gas in equilibrium with the liquid. Thus, the amount of inert gases (eg, nitrogen, helium) dissolved in the blood and tissues increases at higher pressure. During ascent, when the surrounding pressure decreases, bubbles (mainly nitrogen) may form. The liberated gas bubbles can arise in any tissue and cause local symptoms, or they can travel via the blood to distant organs ( Arterial Gas Embolism ). Bubbles cause symptoms by Blocking blood vessels Rupturing or compressing tissue Inducing endothelial damage and extravasation of plasma Activating clotting and inflammatory cascades Because nitrogen dissolves readily in fat, tissues with a high lipid content (eg, in the central nervous system) are particularly susceptible. 