Accessing the efficacy and peri-operative adverse effects of three different hyperbaric bupivacaine 0.5% dosages for spinal anesthesia induction in lower limb orthopedic surgeries: a randomized clinical trial.

BACKGROUND

Spinal anesthesia (SA) is a conventional method for proper nerve block in abdominopelvic and lower extremity surgeries. Compared to general anesthesia, SA has reduced perioperative complications significantly. The hyperbaric type of bupivacaine hydrochloride (HB) induces spinal anesthesia more efficiently with a lower incidence of life-threatening adverse reactions like Perioperative hemodynamic changes and respiratory depression. More investigations are needed to define the best dosage that provides adequate anesthesia while reducing adverse effects for each surgical procedure.

METHODS

This double-blinded randomized clinical trial compared the consequences of the (12.5mg,15mg,20mg) dosages of HB-bupivacaine in elective lower limb orthopedic surgery. Using block randomization, we allocated 60 participants to three (n = 20) study groups. Utilizing the same protocol of anesthesia induction, outcome variables assumed and measured as the incidence of the adverse effects (Hypotension, Anxiety, Bradycardia, Nausea and Vomiting(N/V), Hypoventilation, and Decreased o2 saturation), and the requirement for intervention to control the unwanted reaction. Addressing that, outcome variables were measured 10 times perioperatively. One-way ANOVA test, the chi test, or repeated measures ANOVA test with the Bonferroni adjustment were utilized as appropriate.

RESULTS

We found that the incidence of hypotension (P-value:0.02) and the N/V (P-value < 0.001) are associated with the HB-bupivacaine dosage. Contrary, our findings indicate that the incidence of apnea, bradycardia, and hypoventilation did not exhibit a significant dose-dependent pattern between the groups. Repeated measures analysis revealed significant intergroup differences for Herat rate, systolic, diastolic, and mean arterial pressure (group*time Pvalue < 0.001). The observed differences were more prominent 10-30 min after injection of HB-bupivacaine. The regression model claimed that gender (P-value:0.002) and drug dosage (P-value:0.03) significantly predict the incidence of adverse effects.

CONCLUSION

Our results, suggest that the administration of the 12.5mg HB-bupivacaine provides adequate anesthesia while minimizing the risk of adverse events for lower limb orthopedic surgeries lasting up to 180 min.

TRIAL REGISTRATION

The study was registered at the Clinical Trial Registry Center (IRCT20160202026328N7), Registered on 2022.01.10.