Effect of posture and some c.s.f. characteristics on spinal anaesthesia with isobaric 0.5% bupivacaine.

The effect of the sitting position (0, 2.5, 5.0 or 7.5 min), during and after the injection of 3 ml of 0.5% isobaric bupivacaine-HCl, on the segmental spread of spinal analgesia was studied in 40 patients. Ten patients injected in the lateral horizontal position acted as controls. The spread of analgesia was significantly greater in those who sat for 2.5 min or more compared with those who were immediately put in the supine position. Prolongation of the sitting time did not produce a higher analgesic block. The motor block was complete in all patients; its duration was significantly longer in the horizontal group than in all the sitting groups. There was no significant correlation between the different c.s.f. indices (pressure, protein and chloride ion concentration pH, and specific gravity) and the spinal block.