Comparative Study of Constant Dose Intrathecal Hypobaric Levobupivacaine with Varying Baricities in Lower Limb Surgeries

BACKGROUND: Hypobaric spinal anesthesia is advantageous for unilateral lower extremity fractures as it obviates pain of lying on fractured limb for performing subarachnoid block. AIMS: This study compares block characteristics and complications of three different baricities of constant dose intrathecal hypobaric levobupivacaine to determine an optimum baricity. SETTINGS AND DESIGN: One-twenty American Society of Anesthesiologists Physical Status 1 and 2 patients aged 18–65 years undergoing unilateral lower limb surgeries were divided into three equal groups for this prospective cohort study. MATERIALS AND METHODS: To 2 mL intrathecal 0.5% isobaric levobupivacaine (10 mg), 0.4 mL, 0.6 mL, and 0.8 mL of distilled water were added in Groups A, B, and C, respectively. Baricities of Groups A, B, and C are 0.999294, 0.998945, and 0.998806, respectively. Development of sensory and motor block was assessed by the pinprick method and Bromage scale, respectively. The total duration of analgesia and complications were noted. STATISTICAL ANALYSIS USED: Mean, standard error, one-way ANOVA, and Bonferroni were used to analyze quantitative variables; proportions and Chi-square tests for qualitative variables. RESULTS: Demographic parameters, motor block of operated limb, and complications were comparable. Group C had the fastest onset of sensory block (10.10 min) and maximum duration of analgesia (478.97 min; P < 0.001); but high sensory levels in 48.7%. Group B had T(10) sensory level in 92.5%; onset comparable to Group C (P = 0.248), and reasonable duration of analgesia (332.50 min). Group A had inadequate sensory levels, slow onset, and early regression. CONCLUSIONS: Group B (baricity - 0.998945) has better block characteristics among three groups compared.