A Randomized Controlled Trial Comparing Isobaric Versus Hypobaric Plus Isobaric Bupivacaine in Thoracic Segmental Spinal Anesthesia for the Reduction of Shoulder Pain During Laparoscopic Cholecystectomy.

Introduction Laparoscopic cholecystectomy (LC) is traditionally performed under general anesthesia (GA). However, thoracic segmental spinal anesthesia (TSSA), where low doses of local anesthetics (LA), often with adjuvants, are used at thoracic spinal levels, is also being explored by some researchers. Shoulder pain is a common issue during LC, adversely impacting the patient's perioperative experience. A combination of hypobaric and isobaric LA at the thoracic level has been described to mitigate this complication. The primary objective of the study was to compare the efficacy of a combination of hypobaric and isobaric bupivacaine versus isobaric bupivacaine alone during TSSA in LC in reducing intraoperative shoulder pain. The secondary objectives were to assess the incidence of adverse effects (hypotension, bradycardia, nausea, vomiting, etc.) and to evaluate patient and surgeon satisfaction. Methods This randomized, controlled, open-label study was conducted at a tertiary care center after receiving ethical approval and registration at the Clinical Trial Registry of India. A total of 90 patients were recruited, with 45 participants in each group, aged 20-70 years, with ASA Physical Status I-II, scheduled for elective LC. Exclusion criteria included BMI > 35, contraindications to regional anesthesia, allergy to study drugs, spinal deformity, and previous abdominal surgery. Patients were randomly assigned to two groups using computer-generated random numbers. Anesthesia was provided by a senior consultant proficient in TSSA. Group 2 received hypobaric and isobaric bupivacaine, and Group 1 received only isobaric bupivacaine. Both groups received 11 mg bupivacaine with 5 μg dexmedetomidine in TSSA. Data were collected using Microsoft Excel (Microsoft® Corp., Redmond, WA, USA) and analyzed using IBM SPSS Statistics for Windows, Version 23 (Released 2015; IBM Corp., Armonk, NY, USA). Continuous variables were expressed as means ± SD and analyzed using an independent t-test or the Mann-Whitney U-test, depending on the distribution of data. Categorical variables were compared using the Chi-square or Fisher's exact test. A p-value of <0.05 was considered statistically significant. Results All 90 patients in both groups successfully underwent LC under TSSA with no conversion to GA. The mean age of the participants was 49.11 ± 7.4 years with 58 (64.4%) females. Both groups were comparable in terms of demographic parameters. Intraoperative clinical parameters were comparable in both groups, without any statistically significant differences. Six (13.3%) patients in Group 1 and five (11.1%) patients in Group 2 had hypotension, which was easily corrected with a fluid bolus and a single 6 mg dose of intravenous mephentermine. Six (13.3%) patients in Group 1 reported shoulder pain, whereas in Group 2 only one (2.2%) patient had shoulder pain intraoperatively. Patient and surgeon satisfaction scores were better in Group 2, which was statistically significant. The number needed to treat (NNT) of nine indicates that approximately nine patients would need to receive the hypobaric + isobaric regimen to prevent one case of intraoperative shoulder pain. Conclusions LC can be performed successfully under TSSA with stable hemodynamics. The addition of hypobaric bupivacaine to isobaric bupivacaine provided better shoulder-tip pain control and fewer postoperative complications. Further studies with larger sample sizes are needed to validate these findings.