Evaluation of Effect of Hip/Shoulder-Width Ratio on the Sensory Level of Spinal Anesthesia - A Prospective Observational Study.

Background: Certain anthropometric measurements that are practically obtainable explain the variability in the spread of spinal anesthesia. These are useful for quick assessment of the spread of spinal anesthesia to avoid the risk of high block and also the inadequate level of block.

Aims: The study aims to evaluate the effect of hip/shoulder-width ratio (HSR) on the sensory level of spinal anesthesia.

Settings and design: This prospective observational study was undertaken at a tertiary care hospital.

Statistical analysis: Pearson's correlation and multiple linear regression analyses were used to analyze the relationship between study variables with the level of sensory block.

Materials and methods: One hundred patients undergoing various surgical procedures were enrolled for the study. With a patient in a sitting position, hip-width was measured between the two iliac crests, shoulder-width was measured between two acromion processes, and vertebral column length was noted by measuring the distance from C₇ vertebra to sacral hiatus. 3 mL of 0.5% hyperbaric bupivacaine was administered intrathecally at L₃-L₄ with 25G Quincke's needle in the lateral position. Assessment of block level was done by loss of cold sensation and loss of pinprick sensation every 5 min till 30 min. The numbers of segments blocked were noted from the S₅ segment. The relationship between various factors with the level of sensory block was analyzed by the Pearson's correlation coefficient.

Results: HSR and body mass index (BMI) have a significant correlation with the sensory level of spinal anaesthesia, HSR (r = 0.297, P < 0.05) and BMI (r =0.385, P < 0.05).

Conclusion: HSR can help predict the cephalad spread of spinal anesthesia. We can expect a higher level of sensory blockade of spinal anesthesia in females who generally have an HSR more than one.