Patient- and Operator-Related Factors Associated With Difficult Thoracic Epidural Catheter Placement: A Retrospective Observational Study.

Background Thoracic epidural catheter placement can be technically challenging because of the anatomical characteristics of the thoracic spine. Here, we aimed to identify patient- and operator-related factors associated with difficult thoracic epidural catheter placement, defined as requiring two or more skin punctures. Methods In this retrospective observational study, we analyzed the data of consecutive adult patients who underwent thoracic, abdominal, or pelvic surgery under general anesthesia combined with thoracic epidural anesthesia. Patient- and operator-related factors associated with difficult thoracic epidural catheter placement were evaluated using multivariable logistic regression analysis. Difficult placement was defined as requiring two or more skin punctures. Results Among 304 consecutive patients who underwent the procedure between June 1 and December 31, 2025, 4 were excluded owing to insufficient documentation, leaving 300 patients for analysis. Difficult placement occurred in 144 patients (48.0%). In the multivariable logistic regression analysis, older age (adjusted odds ratio, 1.02 per year; 95% confidence interval, 1.00-1.04; p = 0.049), higher body mass index (adjusted odds ratio, 1.14 per kg/m²; 95% confidence interval, 1.06-1.22; p < 0.001), and use of the paramedian approach (adjusted odds ratio, 4.94; 95% confidence interval, 2.95-8.45; p < 0.001) were associated with a higher likelihood of difficult placement. More years of anesthesiology experience were associated with a lower likelihood of difficult placement (adjusted odds ratio, 0.89 per year; 95% confidence interval, 0.83-0.95; p < 0.001). Difficult placement was also associated with longer procedure time and greater measured depth to the epidural space. Thoracic puncture level (Th) and a history of spinal disease or surgery were not independently associated with difficult placement. Conclusions Older age, higher body mass index, and less operator experience were associated with difficult thoracic epidural catheter placement. Assessing these factors before the procedure may help clinicians anticipate technical difficulties and plan the procedure accordingly. A significant association was also observed between the paramedian approach and difficult placement, but its clinical implication remains uncertain.