Abstract
Introduction: Many factors have been tested to predict the spread of spinal anesthesia in clinical practice. In the study, we aimed to investigate the correlation between hip/shoulder width ratio and spread of spinal anesthesia.
Method: Sixty patients were enrolled in this study to determine the correlation between hip/shoulder width ratio and the spread of spinal anesthesia. The L4-L5 interspace, navigated by ultrasonography, was introduced at the lateral position with a 25G spinal needle. 3ml 0,5% hyperbaric bupivacaine was injected intrathecally in 15 seconds. Age, height, weight, body mass index, hip/shoulder width ratio, and vertebral column length were recorded. Spinal anesthesia spread was assessed at 0, 5, 10, 20, and 30 minutes after spinal anesthesia. The patient was turned supine 5 minutes after intrathecal injection. Multiple linear regression analysis was used to analyze the correlation between the spread of spinal anesthesia and age, height, weight, hip/shoulder width ratio, vertebral column length.
Results: The study was completed without dropout and sixty participants were included in the analysis. There was a strong correlation between the spread of spinal anesthesia and hip/shoulder width ratio (r=0,766; p<0,0001) and a negative correlation with the height and vertebral column length (r= -0,572; -0,738 and p=0, 000; 0, 000 respectively).
Conclusion: Cephalad spread of spinal anesthesia with a fixed dose of hyperbaric bupivacaine is strongly correlated with hip/shoulder width ratio and inversely correlated with height and vertebral column length. We may observe more spread with 0, 5% hyperbaric bupivacaine in patients with a greater hip/shoulder ratio and a shorter height.

Key words: Spinal anesthesia, hyperbaric bupivacaine, hip/shoulder ratio