Sedation with 1 mg Intravenous Midazolam in Subarachnoid Block with Bupivacaine and Fentanyl for Lower Limb Surgeries Causes Clinical Sedation without Hemodynamic Compromise: A Randomized Controlled Trial

Background: In young healthy males intravenous (IV) sedation in subarachnoid block (SAB) is reported to causecardiac arrest. Thus frequently IV sedation in SAB is frequently discouraged.Hypothesis of the present study was that SAB with bupivacaine and fentanyl would correspond to a BIS < 90,level of clinical sedation and IV midazolam 1 mg in such patients may cause hemodynamic compromise.Primary objective was to compare BIS post SAB with and without IV midazolam. Secondary objective was tocompare hemodynamic parameters.Methods: 60 patients of age 20-60 years, ASA 1 or 2, undergoing lower limb surgeries were given SAB with0.5% hyperbaric bupivacaine 2 mL (10 mg) and fentanyl 0.5 mL (25mcg). Thereafter Group A (n=30) was givenSAB with 1ml IV saline and Group B (n=30) was given SAB with IV 1mg midazolam.Parameters were recorded at baseline, then every 15 minutes till 90 minutes.Results: In Group B, BIS < 90 but not < 80 was noted from 30 minutes to at least 90 minutes. In Group A, BIS <90 was noted from 45 minutes to 60 minutes and was > 90 at all other time frames. Mean BIS was significantlymore in Group A compared to Group B (90.41 +/- 4.05 v/s 86.58 +/- 3.50 respectively) (P< 0.001). Hemodynamicparameters of heart rate, non-invasive blood pressure, oxygen saturation and respiratory rate were comparablebetween both groups (p value >0.05).Conclusion: SAB does not result in adequate intra operative patient sedation. IV midazolam 1 mg causes BIS<90 from 30 minutes till at least 90 minutes without hemodynamic compromise.