Erythrocyte counts in the cerebrospinal fluid associated with continuous spinal anaesthesia

Continuous spinal anaesthesia technique can be associated with peridural haemorrhage due to blood vessel damage caused by the needle or the catheter. We studied whether thrombosis prophylaxis or anticoagulation medications increase the risk of subarachnoid haemorrhage when continuous spinal anaesthesia is used. Twenty arthroplasty patients received low-molecular-weight heparin preoperatively and twenty-two vascular surgery patients received heparin (100 IU kg-1) peroperatively; eight of the latter patients were on regular preoperative antiplatelet medication. Twenty-four prostate surgery patients, not exposed to heparin or other drugs affecting coagulation, served as controls. A 22-gauge spinal catheter was used and bupivacaine was injected through the catheter. Within the following 24 hours, 4-5 cerebrospinal fluid samples were collected for erythrocyte counts. In the arthroplasty and the vascular group there were five patients each and in the control group seven patients with more than 100 x 10(6) l-1 erythrocytes in at least one of the samples. The highest erythrocyte count was 23900 x 10(6) l-1 in a control patient. The 24-hour sample was blood-tinged (erythrocytes > 1000 x 10(6) l-1) in two patients in the arthroplasty group, in one patient in the vascular group and in four patients in the control group. In spite of the haemorrhages detected in this study, no related neurological symptoms or other serious consequences were observed. The risk of subarachnoid haemorrhage was not increased by drugs affecting coagulation.