Correlation between Abdominal Girth and Skin to Epidural Space Distance of Thoracic and Lumbar Spine: A Cross-sectional Study

Abstract

Introduction: The Skin-to-Epidural Space Distance (SESD) is likely to be different at two different parts of the spine in the same individual and also in the same part of the spine in two different individuals. The knowledge of the expected depth of the epidural space can be very useful in placing the epidural needle appropriately and avoiding unwanted dural puncture. Although many studies have been conducted to study the relation of lumbar SESD with various physical and anthropometric parameters, the literature on thoracic SESD is scant. Aim: To determine the correlation between SESD and Abdominal Girth (AG) in the mid-thoracic, lower thoracic, and lumbar regions of the spine in adult patients scheduled for elective surgical procedures. Materials and Methods: After obtaining Ethics Committee clearance (EC/NIMS/2671/2020, 51st ESGS No: 1082/2020), this prospective observational study was carried out at Nizam’s Institute of Medical Sciences, Hyderabad, India, from October 2021 to February 2022. The study recruited 202 patients, and data from 194 patients was analysed. During the preoperative visit, all physical parameters, including AG, were noted. Using an 18G Tuohy needle, the epidural space was identified, and SESD was measured. Its correlation with AG, age, height, weight, and body mass index was studied. The data was analysed using the Statistical Pacakge for Social Sciences Software (SPSS) (2011, IBM, Armonk, NY, United States of America) version 20.0. Results: The mean SESD was 4.7±1.09 cm in the mid-thoracic region, 4.71±0.98 cm in the lower thoracic region, and 4.8±0.82 cm in the lumbar region. The correlation coefficient of SESD with AG was 0.42, 0.44, and 0.78 in the mid-thoracic, lower thoracic, and lumbar regions, respectively, and the significance level was <0.001 in all three regions. Body weight had a good correlation (r-values of 0.56, 0.66, 0.53 in mid-thoracic, lower thoracic, and lumbar areas, respectively, and p-value of <0.001 in all three anatomical regions of the spine) with SESD. All other physical parameters were correlated weakly with SESD. Conclusion: AG has a strong correlation with SESD in the lumbar area but a moderate correlation in the thoracic spine. SESD in the lumbar, mid, and lower thoracic regions have a good correlation with weight.

Keywords

• epidural anaesthesia
• epidural analgesia
• body mass index