Shock

Shock, or circulatory shock, is a medical emergency in which the heart and blood vessels can no longer supply the body's cells with enough oxygen and fuel to keep their metabolism going. It is unrelated to emotional shock. Starved cells begin to fail, and organs such as the kidneys, brain and heart can be damaged quickly.

Shock is grouped by cause. Hypovolemic shock follows heavy loss of blood or body fluid, as in bleeding, burns or severe diarrhea. Cardiogenic shock occurs when the heart itself pumps too weakly, most often after a heart attack. In distributive, or vascular, shock, small arteries relax and widen so pressure collapses; septic, anaphylactic and neurogenic shock belong here. Obstructive shock comes from a blockage, such as a clot in the lungs or fluid squeezing the heart.

Typical signs are low blood pressure, a fast but weak pulse, pale, cool and clammy skin, little urine, rapid shallow breathing and confusion. Left untreated, shock tends to worsen itself in a vicious circle and can be fatal, so treatment aims to restore blood flow quickly while correcting the cause.