[Effect of glucose concentration on spinal anesthesia with bupivacaine 0.5%]

Until recently isobaric agents were relatively seldom employed to produce spinal anaesthesia. Experience with bupivacaine has shown in a prospective study on 60 patients, that complications, especially with high or total spinals, are uncommon with either using hyper- or isobaric agents. Also it has been shown that the height of blockade after using hyperbaric agents can only be crudely controlled by positioning of the patient. 3 ml (15 mg) of 0.5% bupivacaine produces adequate analgesia, and muscle relaxation, rapidly, in the vast majority of patients. The duration of blockade was adequate for longer surgical procedures, and was not affected by varying glucose concentrations in the solutions employed. Also there was no difference in the number of dermatomes blocked. No significant differences could be found between the solutions containing 5 or 8% glucose; however, with the 8% concentration smaller variations were found in regard to the extent of dermatomal blockade. The degree of motor block was identical in all 3 groups. The duration of motor block decreased when using higher concentrations of glucose. It is not clear whether the differing glucose concentrations have an effect on C.S.F. osmolarity, and whether this is clinically relevant. The results show that isobaric spinal anaesthesia is at least as reliable as hyperbaric spinal anaesthesia.