Using “Baudhayana Theorem” for a Novel Paramedian Approach of Spinal Anesthesia in Morbidly Obese Patients with Difficult Sonoanatomy: A Case Report and Narrative Review

Spinal anesthesia is traditionally performed using landmark technique to identify the level and point of needle insertion. However use of ultrasonography (USG) has emerged among anaesthesiologists to guide neuraxial blockade. The views that are of utmost importance are “transverse spinous view”, “transverse interspinous view” and “longitudinal parasagittal oblique view”. For in-plane technique and real time imaging longitudinal parasagittal oblique view is used while transverse views are used for visualizing spinous level, epidural and subarachnoid space, posterior complex (PC), anterior complex (AC) and depth of canal. In patients with deformed spine like kyphoscoliosis or morbid obesity obtaining optimum views is not possible. We discuss a morbidly obese patient with very poor ultrasonographic views of spine. We describe a novel technique to estimate depth of spinal canal using only bony shadows in a single transverse view.