The effect of hyperbaric bupivacaine dose on the incidence and severity of early complications after spinal anesthesia for orthopedic surgeries

Abstract

Spinal anesthesia using bupivacaine hydrochloride is a common technique used during surgical procedures. Two forms of bupivacaine, isobaric bupivacaine and hyperbaric bupivacaine, are available for use, with hyperbaric bupivacaine being more effective due to its higher specific gravity. However, the appropriate dosage to use remains unclear due to small sample sizes and inconsistent outcomes in existing studies. This study aims to provide evidence-based guidance on the dosage of bupivacaine for SA during orthopedic surgeries. Method: This randomized, double-blind clinical trial investigation included 60 patients aged 18 to 60 who were sent to Shahada Hospital for elective lower limb surgery. The participants were randomly separated into three groups and given three doses of 0.5% hyperbaric bupivacaine medication into the intrathecal space (A: 12.5mg, B: 15mg, C: 20mg). Then they had the same lower limb surgery. Vital signs (including heart rate, respiratory rate, oxygen saturation, systolic blood pressure, and diastolic blood pressure) were measured immediately before, immediately after, and at intervals of 5 minutes to half an hour and 15 minutes to an hour. Results: There were no significant differences in gender, age, ASA classification, weight, height, and body mass index (BMI) between the three groups. Most patients in each group were classified as Class II by the American Society of Anesthesiologists. The changes observed during the serial measurement of vital signs are as follows: In the 45th minute after the block, a significant difference in heart rate reduction was observed with higher doses, but in other measurements, there was no significant difference in the heart rate trend between the groups. There was no significant difference in systolic blood pressure, blood oxygen saturation and incidence of nausea and vomiting between groups. At 10 and 15 minutes after the block, a significant difference was observed in the reduction of diastolic blood pressure by receiving higher doses, but in other measurements, there was no significant difference in the trend of diastolic blood pressure between the groups. In the 15th minute after the block, a significant difference was observed in the reduction of mean arterial pressure with higher doses, but in other measurements, there was no significant difference in the trend of mean arterial pressure among the groups. Immediately after the block and in 30 and 45 minutes after the block, a significant difference was observed in the reduction of breathing rate with higher doses, but in other measurements, there was no significant difference in the trend of breathing rate among the groups.