[Prerequisites of a functional haemostasis. What must be considered at the scene of an accident, in the emergency room and during an operation?].

A coagulopathy is an independent predictor of perioperative mortality. Therefore, maintenance of a functional coagulation system is an essential precondition to reduce morbidity and mortality in the perioperative setting. Sound coagulability also depends on prerequisites such as body temperature, acid-base balance, plasma calcium concentration and haematocrit. Severe trauma or perioperative bleeding can gravely influence these factors and boost the blood loss. Common global tests of coagulation are not helpful in this setting because they are conducted on plasma with a normalised temperature of 37 degrees C, an excess of calcium and a stabile acid-base balance. Hence, knowledge of the effects of altered prerequisites is a premise to avoid a possibly lethal coagulopathy. According to the current literature, an increased risk for clinically significant coagulopathy exists with a body temperature <or=34 degrees C, an acidosis <or=7.15, ionised calcium under 0.9 mmol/l or a haematocrit under 30-35%. A combination of these factors deteriorates the coagulopathy and hypothermia in addition to acidosis is especially harmful. Prevention of derangement of these factors should start as early as possible, i.e. in trauma patients at the scene of the accident and should be continued in the operating room.