Pre-procedural ultrasound assisted landmark identification for epidural catheterization: a prospective observational study

Background: Placement of thoracic epidural is technically challenging and demands precise anatomical knowledge .This study used pre-procedural ultrasound for thoracic epidural catheter placement in high BMI patients undergoing oncosurgeries. Accuracy of ultrasound assisted method and palpation method in locating and measuring thoracic epidural space depth is studied. Additionally, the study seeks optimal needle insertion point to minimize the attempts. Methods: A prospective observational study included ASA I and II patients aged > 18, with BMI >/=25, scheduled for elective oncosurgeries with thoracic epidural for pain relief. Forty eligible patients who had thoracic epidural placement were observed and studied. The time for skin markings, loss of resistance, and number of attempts, needle skin puncture, and needle redirection were recorded and analysed. Results: Age and BMI were comparable between two groups. Mean time for epidural needle placement to achieve loss of resistance in group A (159.300sec) and group B(379.150sec) respectively (P = 0.015). Ultrasound assisted skin marking took 92.550 sec for A and 39.950 sec for B (P = 0.379). Number of attempts for group A was 1.650 and B was 1.900(P = 0.293). Ultrasound assistance for skin marking, depth of epidural space, number of attempt, needle skin puncture and needle redirection were comparable. Conclusion: Pre-procedural ultrasound markedly reduced time for loss of resistance. However, factors like time for skin marking, number of attempts, depth of epidural space, needle skin puncture and redirection not significantly different compared to palpation.