Actual depth of subarachnoid space - A correlation between subarachnoid space depth estimated by stocker’s formula, craig’s formula and ultrasound guided spinal anaesthesia in the lumbar region

Abstract

In any patient, the skin to subarachnoid space depth varies significantly at completely different levels of the spinal cord and it additionally varies from patient to patient at the same vertebral level as per patient characteristics like age, sex and body mass index. An estimate of the skin to subarachnoid space depth has been shown to minimize the number of unsuccessful tries, consecutive attempts, traumatic or blood-filled lumbar punctures, typically acting as a depth guide for correct spinal needle placement. In this study we estimated the subarachnoid space depth using ultrasound, stocker’s formula and craig’s formula to determine which provided better correlation to the actual subarachnoid space depth. This study is a Prospective observational study done in the Department of Anaesthesiology, Saveetha Medical College and Hospital, Chennai from August 2020 to February 2021.This study concluded that Ultrasound guided measurement of subarachnoid space depth provided better correlation with actual subarachnoid space depth compared to stocker’s and craig’s.