The Effect of Intravenous Midazolam on Duration of Spinal Anesthesia

Abstract

Background: A variety of systemic and intrathecal adjuvants to local anesthetics have been found to expand the duration and improve the quality of spinal block and decrease pain after surgeries. Objectives: The aim of this study was to evaluate the effect of the addition of midazolam to lidocaine for spinal anesthesia in lower abdomen and lower limb surgeries. Patients and Methods: In a prospective, randomized, double blind study, 36 patients aged 20 to 60 years, and American Society of Anesthesiologists (ASA) I or II, were randomly allocated to receive either intravenous midazolam (30 μg/kg) or placebo in spinal anesthesia. Level of sensory block, time to achieve maximum motor and sensory block, duration of sensory and motor block, recovery time, side effects, heart rate, blood pressure, arterial oxygen saturation and sedation score were measured and analyzed using the SPSS software version 15 by t-test and ANOVA. Data were considered significant at 0.05. Results: The motor block duration in midazolam and control group was 82.9 ± 27.3 and 59.1 ± 26.5, respectively (P = 0.01). However the duration of sensory block was not different between the two groups (P = 0.07). The median of sensory block level was at T8 and T10 in midazolam and control group (P = 0.02). Recovery time was more prolonged in the midazolam group (P = 0.002). Hemodynamic indices did not show any significant differences between the two groups. Conclusions: Addition of 30 μg/kg midazolam to lidocaine for spinal anesthesia improved duration of motor block and increased intraoperative sedation score without causing side effects in patients’ requiring lower abdomen and lower limb surgery.