Haemothorax--a source of error in emergency central vein cannulation.

Central venous cannulation is often performed in patients with penetrating wounds of the chest as an aid to diagnosis, and is sometimes also used as a volume infusion resuscitation line in an emergency. The traditional signs of successful central venous cannulation--free aspiration of blood from the exploring needle and inserted cannula, free infusion flow and backflow of blood when the set is lowered below the patient--may all give a false impression of correct placement if there is a significant haemothorax on the same side. Two cases are described where the cannula was sited in a pleural cavity which contained blood, leading to inadequate resuscitation of the patient. The authors recommend that, where possible, peripheral lines or saphenous cutdown be used for volume resuscitation and that central venous cannulation in the emergency situation be performed on the side of the uninjured hemithorax, especially if the operator is inexperienced.