Regional anesthesia in the anticoagulated patient: Yes or no

Abstract

PINAL HEMATOMA is a rare and potentially catastrophic complication of spinal or epidural anesthesia. The actual incidence of neurologic dysfunction resulting from hemorrhagic complications associated with central neural blockade is unknown; however, the incidence cited in the literature is estimated to be less than 1 in 150,000 epidural and less than 1 in 220,000 spinal anesthetic cases. 1 Hemorrhage into the spinal canal most commonly occurs in the epidural space because of the prominent epidural venous plexus. Although hemorrhagic complications can occur after virtually all regional anesthetic techniques, bleeding into the 'spinal canal is perhaps the most serious hemorrhagic complication associated with regional anesthesia because the spinal canal is a concealed and-nonexpandable space. Spinal cord compression from spinal hematoma may result in nenrologic ischemia and paraplegia. Spinal hematoma may occur due to vascular trauma from needle or catheter placement into the subarachnoid or epidural space (Fig 1). However, it also may occur in association with neoplastic disease or pre-existing vascular abnormalities. Of special interest to the anesthesiologist are those spinal hematomas that have occurred spontaneously with or without the presence of antiplatelet or anticoagulation therapy. Over 100 spontaneous epidural hematomas have been reported, 25% of which are associated with anticoagulation therapy. 2 In a review of the reports appearing in the literature between 1906 and 1994, Vandermeulen et al 3 discussed 61 cases of spinal hematoma associated with epidural or spinal anesthesia. In 42 of the 61 (68%) patients, the spinal hematomas associated with central neural blockade occurred in patients with evidence of hemostatic abnormality. Twenty-five of the patients had received intravenous or subcutaneous heparin; as they were undergoing a vascular surgical procedure, an additional five patients were presumably administered heparin. In addition, 12 patients had evidence of coagulopathy or thrombocytopenia or were treated with antiplatelet medications (aspirin, indomethacin, ticlopidine), oral anticoagulants (phenprocoumone), thrombolytics (urokinase), or dextran 70 immediately before or after the spinal or epidural anesthetic. Needle and catheter placement was reported to be difficult in 15 (25%) or bloody in 15 (25%) patients. Thus, in 53 of the 61 (87%) cases, either a clotting abnormality or needle placement difficulty was present. To reduce the risk of spinal hematoma associated with central neural blockade, it is necessary to understand the mechanisms of blood coagulation, the pharmacologic properties of the anticoagulant and antiplatelet medications, and the clinical studies involving patients undergoing central neural blockade while receiving these medications. While this discussion will deal mainly with continuous techniques of major conduction blocks and anticoagulants, the same principles apply to all regional anesthetic techniques.