Transverse ultrasound scanning of lumbar-epidural depth and its co-relation with conventional method: A prospective observational study in obese Indian parturients

Pre-procedural ultrasound (US) imaging as a tool of determining the proper insertion site and assessing lumbar-epidural depth in obese Indian parturients. The current study’s goal was to assess the epidural depth space in obese Indian parturients by ultrasound imaging with conventional technique and also to assess whether if it decreases the failure rate and number of attempts. Twenty-five obese parturients with a BMI of more than 30 kg/m who were scheduled for elective lower segment caesarean sections under lumbar epidural anesthesia and were classified as American Society of Anaesthesiology grade I & II were included. Using a curvilinear US probe (frequency 2–5 MHz), ultrasound depth-UD (lumbar epidural) was recorded in the transverse axial plane at the L3–L4 and L4–L5 intervertebral regions. Afterwards, the needle depth (ND) was monitored using a sterile linear scale during the epidural administration process using the traditional loss of resistance (LOR) approach. Any modifications to the intervertebral spacing, needle reorientation, or the quantity of tries were recorded. The results showed that UD and ND were, respectively, 4.6140 ± 0.252 cm (range 4.20–5.30 cm) and 4.720 ± 0.271 cm (range 4.2–5.5 cm). Pearson's correlation coefficient (r) for UD and ND was 0.953 (95% confidence interval: 0.8948–0.9793, r = 0.908, P < 0.001), and the 95% limits of agreement were found to be 0.266 to 0.546 cm using Bland-Altman analysis. Of all the subjects, 92% needed only one try to put the epidural, whereas 8% needed two. The current study demonstrates a significant association of ultrasound (UD) and needle depth (ND) in obese pregnant females (BMI >30 kg/m). For lumbar epidurals, a preprocedural US scan in the transverse-axial plane provides a precise needle entry site with a high success rate.