Bispectral index monitoring of propofol sedation during ultrasound guided nerve block for inguinal herniorraphy: A randomized prospective study

BACKGROUND: Patient's awareness can be reduced during ultrasound guided nerve block for inguinal herniorraphy with propofol sedation. The study was aimed to evaluate the clinical efficacy of direct visualization of anatomy of inguinal region by ultrasound and benefits of bispectral index (BIS) monitoring. MATERIALS AND METHODS: After approval, 40 adult male consented patients of ASA grade I-III of 18-58 years with body mass index <25 were randomized into two groups of 20 patients each. A high frequency (8-13 MHz) linear transducer was used to perform the ilioinguinal and iliohypogastric nerves (ILHN and ILIN) block between the internal oblique and transversus abdominis muscles with 20 mL of 0.75% ropivacaine. The propofol infusion rate for sedation in patients of group I (non-BIS) was managed clinically and in patients of group II (BIS) was managed with BIS index of 65-75. Any surgical or anesthetic complications were recorded. The two groups were compared by evaluating the propofol consumption during surgery. RESULTS: Ultrasonographic visualization of the ILHN and ILIN was possible in all patients and inguinal herniorraphy was performed uneventfully. The mean dose of propofol required for sedation was 5.45 mg/kg/h in patients of group I (non-BIS) while 4.92 mg/kg/h in patients of group II (BIS). The mean propofol consumption was not statistically significant (P = 0.12). All patients were hemodynamically stable and there was no respiratory depression during propofol sedation. CONCLUSION: Ultrasonography has facilitated the clinically effective nerve block for inguinal herniorraphy and BIS monitoring has ensured amnesia and faster emergence.