[Heparin and spinal or epidural anesthesia: decision analysis]

The incidence of thromboembolism justifies prophylactic measures, the most efficient of which is the use of heparin. However this agent may be responsible for haemorrhagic complications during regional anaesthesia. The risk of bleeding in a poorly accessible area, e.g. the epidural space, the brachial plexus sheet, the space behind the eyeball, is one of the concerns of anaesthetists. A review of case reports of haemorrhagic complications of spinal anaesthesia shows that the risk of bleeding or of spinal haematoma is very low. In fact, a blood or epidural vessel is punctured in 2.8 to 11.5% of cases of epidural anaesthesia, without any sequelae. Some authors suggest that low molecular weight heparin may be given to patients before spinal anaesthesia. In all cases, patients should be carefully assessed before, during and after the procedure, clinically and biologically. The absolute contra-indications to these techniques are a refusal by the patient, an uncooperative patient, severe coagulation disorders, untreated hypovolaemia, infection of the puncture site, severe generalized infection, and raised intracranial pressure. Decision as to whether a regional anaesthetic technique should be used in a particular patient who is under anticoagulant treatment, or who is to receive such a treatment intra or postoperatively, must be made on an individual basis. The risk of thromboembolism must be weighted against the risk of haemorrhagic complications. Unfortunately, in the absence of relevant studies, anaesthetists can only rely on their clinical judgment.