Single-dose spinal anaesthesia versus incremental dosing for lower limb vascular surgery.

Abstract

In patients scheduled for vascular surgery, atherosclerotic disease is highly prevalent. Haemodynamic reactions are often aggravated when spinal analgesia is used in this population. No randomized studies have been conducted comparing single shot (SS) with continuous spinal analgesia (CSA) for vascular patients. We did a prospective randomized study comparing haemodynamics when SS versus CSA was performed. Sixty patients were randomized to have SS or CSA. The power of the study was 0.90. Patients in the SS group received 17.5 mg bupivacaine and in the CSA group 5 mg was given initially and incremental doses of 2.5 mg were given until an analgesic level of T-11 was reached. Mean arterial pressures (MAP) were measured invasively. ST-analysis was done continuously. Postoperatively, the patients were interviewed using a standardized questionnaire. Back pain, neurologic sequelae and post-dural puncture headache (PDPH) were investigated. There was no significant difference between the analgesic levels (T-7/T-8), the decrease in MAP, the number of patients needing ephedrine and the total amount of ephedrine given in the two groups. The motor blockade was more pronounced in the SS group (P < 0.001) and the total amount of bupivacaine used was 17.5 mg compared to 7.5 mg (5-17.5) in the CSA group (P < 0.001). One patient suffered PDPH which was slight and responded to a nonsteroidal anti-inflammatory drug. Two patients in each group had transient paraesthesias in the legs. There were technical problems with the spinal catheter in 4 patients, and these were excluded from the study. In this study we found no difference in the haemodynamic response to SS or CSA in patients scheduled for vascular surgery of the legs. SS is easier to apply and is recommended when the duration of surgery allows for it.