UNILATERAL SPINAL-ANESTHESIA WITH HYPERBARIC BUPIVACAINE

Background: The dosage of local anaesthetic and the time the patient m ust be kept in the lateral decubitus position for a unilateral spinal anaesthesia is not known. The aim of this study was to determine the i deal dosage of hyperbaric bupivacaine and the time required for the la teral decubitus position for a unilateral spinal block. Methods: Ninet y patients who were scheduled to receive spinal block for surgery in t he lower extremity were randomised into 9 groups (n=10). The spinal bl ock was performed through the L-4-L-5 intervertebral space with the pa tient in the lateral decubitus position. Patients in groups Ia, Ib, Ic ; IIa, IIb, IIc; IIIa, IIIb, IIIc received 1.5 ml of 0.5%, 2 ml of 0.5 %, and 2.5 ml of 0.5% hyperbaric bupivacaine solutions, respectively. The patients were turned to the supine position for 5 min after the in jection in groups Ia, IIa, IIIa, 10 min after the injection in groups Ib, IIb, mb, and 15 min after the injection in groups Ic, IIc, IIIc. T he onset and regression of sensory and motor block were checked and co mpared between the dependent and non-dependent sides in each group. Re sults: The rate of block progression of the non-dependent side was hig her in the groups receiving 2.5 ml 0.5% hyperbaric bupivacaine solutio n than in the other groups; at the same time the level of block was hi gher and the duration of block was longer. The incidence of hypotensio n was 10-20% in these groups. In the 2 ml 0.5% hyperbaric bupivacaine solution groups, a satisfactory block level and duration of anaesthesi a for surgery was obtained. The rate of block progression to nondepend ent side in the groups receiving 1.5 ml of 0.5% hyperbaric bupivacaine solution was lower than the other groups, but the duration of block w as shorter and the level of block was lower than the other groups. Con clusion: For unilateral spinal anaesthesia in lower extremity operatio ns, 2ml 0.5% hyperbaric bupivacaine solution for operations above the knee and 1.5 ml 0.5% hyperbaric bupivacaine solution for operations be low the knee and keeping the patients for 10 min in the lateral decubi tus position were found to be appropriate.