Combination of symptoms resulting from sudden deficiencies in the circulation of the blood. Shock is characterized by low blood pressure, rapid heartbeat, cold hands and feet, clammy skin and changes in mental condition varying from drowsiness to agitation. The foremost causes of shock are: a) shortage of blood in the circulatory system; b) circulatory disorders caused by heart conditions; c) sudden severe dilation of the blood vessels, causing too little blood to flow through the system. Shock caused by blood shortage is the most common, as a result of internal or external haemorrhage. Treatment is by blood transfusion and staunching the haemorrhage, to which end an emergency operation is almost always necessary. When the heart is the cause it pumps insufficient blood through the system. This can happen as a result of coronary infarction, in which part of the heart no longer functions; heart rhythm disorders can also adversely affect the pumping ruction. This form of shock is treated by medication to stimulate the heart and combat rhythmic disorders. If the cause is cardiac infarction the heart often reacts insufficiently to stimulation by drugs, in which case the patient usually dies. Severe dilation of the blood vessels can result from serious blood poisoning or a violent allergic reaction (anaphylaxis). Treatment consists of fluid replacement by infusion, large doses of antibiotics, and drugs to narrow the blood vessels.