Correlation of Anthropometric Measurements and Spread of Spinal Anesthesia in Parturients Undergoing Caesarean Section – A Prospective Observational Study

Context: Spinal anesthesia is the widely preferred type of anesthesia for caesarean section. Determining the ideal intrathecal local anaesthetic dose to attain the desired block is a major clinical challenge. Anthropometric measurements can have an impact on the rate at which spinal anesthesia spreads. Aims: The main aim of the study was to study the correlation of anthropometric measurements and the spread of spinal anesthesia for caesarean section. Methods and Materials: This prospective observational study was conducted in a single tertiary care hospital, over a study period of 1 year. The study included 136 parturients undergoing elective caesarean section under spinal anesthesia. The patient’s height, weight, abdominal circumference (AC), vertebral column length (VCL), hip, and shoulder length were measured. The primary outcomes measured were the time taken for sensory blockade and the maximum level achieved after administration of subarachnoid block using 2 cc of 0.5% hyperbaric bupivacaine. Statistical Analysis Used: Statistical analysis was done using Microsoft Word, Excel, and MedCalc software, applying the suitable method. Results: AC and body mass index (BMI) showed statistically significant positive correlation with the maximum sensory block level (mean ± standard deviation (SD): T4 ± 1 dermatomes), time to reach T4 level (mean ± SD: 4.3 ± 1.1 min), and time to achieve maximum sensory level (mean ± SD: 6.8 ± 1.5 min) ( P < 0.05). Hip/shoulder ratio (HSR) showed weaker but significant correlation with time to reach T4 level ( r = 0.27, P = 0.0263). No significant correlation was found between VCL and measured block parameters. Hypotension occurred in 36 patients (26.5%) and was positively associated with higher AC ( P < 0.05). No bradycardia episodes were noted. Conclusion: This study found that AC and BMI had a strong correlation with the cephalad spread of sensory blockade. The HSR showed a weak correlation only with the time taken to reach T4 sensory level, while VCL showed no predictive value. These easily measurable variables may help titrate local anesthetic doses and explain variations in spinal anesthesia spread.