Correlation Between Anthropometric Measurements and Sensory Block Level of Spinal Anesthesia for Cesarean Section

BACKGROUND: When performing spinal anesthesia for cesarean section, it is important to determine the appropriate anesthetic dose as well as to predict the level of spinal anesthesia. In this study, it was hypothesized that some anthropometric measurements may be related to maximum sensory block and hemodynamic changes. OBJECTIVES: The aim of this study are to find maternal anthropometric values that are correlate with the level of spinal anesthesia. METHODS: Maternal anthropometric measurements, including height, weight, supine and standing abdominal circumference (AC), and hip circumference, were recorded before spinal anesthesia for cesarean section. Spinal anesthesia was induced by administering 8 mg of 0.5% hyperbaric bupivacaine and 20 μg of fentanyl at the L3-L4 interspace. The level of sensory block was determined using pin-prick at 1, 5, 10, and 15 minutes after spinal anesthesia. The sensory block level and hemodynamic adverse events were analyzed in relationship to anthropometric measurements. RESULTS: The supine AC/height ratios significantly correlate with the maximal sensory block level at 5, 10, and 15 minutes after the injection of spinal anesthetic (P = 0.001, P < 0.001 and P < 0.001, respectively). Further, there were significant correlations between body mass index (BMI) and sensory block level at every assessment (P = 0.041, P = 0.002, P = 0.001 and P < 0.001, respectively). When comparing the groups with and without hypotension, BMI, weight, and supine AC/height ratio were found to be significantly higher in the group with hypotension (P = 0.002, P = 0.004 and P = 0.006, respectively). CONCLUSIONS: We conclude that BMI and AC/height ratio correlate with the sensory block level of spinal anesthesia for cesarean section.