Hyperbaric Bupivacaine for Spinal Anaesthesia in Adults Patients: Comparison of Isobaric Bupivacaine 0.5% in 80mg/Ml and 40 Mg/Ml Glucose Solutions

Background: The Baricity of bupivacaine is one of the most important factors to influence the characteristics of distribution of the local anaesthetic and spread of the blockade. Bupivacaine is rendered hyperbaric by adding glucose. The effect of differing degrees of hyperbaricity remains to be evaluated in term of spinal anesthesia blockade. Methods: Hundred patients who underwent lower abdominal, hips, and lower extremity surgeries were randomized into two groups in a double-blind, randomised, parallel group, prospective study. Group I received 0.5% isobaric bupivacaine with 80 mg/ml of glucose, while Group II received 0.5% isobaric bupivacaine with 40 mg/ml of glucose. Injection was made intrathecally in midline position at L3-4 and L4-L5 interspace in sitting position. The measured sensory blockade and motor blockade are the onset and duration. Duration of sensory block was the time measured from the time of the highest block for the regression to the S2 dermatome. Results: Success rate, spread and duration of sensory block were similar in both groups. The highest median level of sensory block was T3 (T2-T7) (median (10th/90th percentiles)) in both groups. Time to reach T10 did not differ between the groups. Power analysis suggested that a total number of 100 adults were required in both groups for a 90% chance at the 0.05 level of significance of detecting a10% difference in success between groups. Categorical data were tested using the chi square test. For continuous data the Mann–Whitney test was used. Results are presented as median (10–90th percentiles), number (%) of cases, the significance was set as P<0.05. Conclusion: These results demonstrate that bupivacaine in 80mg/ml glucose provides reliable spinal anaesthesia of shorter duration and with less hypotension than bupivacaine in 40 mg/ml glucose. The recovery profile for ropivacaine may be of interest given that more surgery is being performed in the day-case setting.