The Effectiveness of Intraoperative Thoracic Epidural Analgesia in Major Abdominal and Thoracic Surgery and Its Prediction of Severe Pain at Discharge from the Post-Anesthetic Care Unit: A Prospective Cohort Study

Objective: To assess the factors associated with ineffective thoracic epidural analgesia (iTEA) in the post-anesthesia care unit (PACU) among patients requiring TEA. Material and Methods: This prospective cohort was conducted on 146 patients requiring post-operative TEA. The verbal numeric rating scale (VNRS) was employed to assess TEA effectiveness on PACU arrival at 10, 20, and 30 minutes after surgery; iTEA was determined if the VNRS score was more than 3 and 4 at rest and during activity, respectively. The patient characteristics, and intra- and post-operative epidural management were collected. The risk factors of iTEA were evaluated using mixed-effects models. Moreover, factors associated with severe pain at PACU discharge were evaluated using logistic regression analyses. Results: The incidence of iTEA on PACU arrival, and at 10, 20, and 30 minutes after PACU arrival were 53.4%, 51.4%, 50.7%, and 36.3%, respectively. Intra-operative intravenous morphine supplementation and the cumulative fentanyl equivalent dose (every 10 mcg) were significantly associated with preventing the risk of iTEA on PACU arrival (OR 0.27; 95% CI=0.07-0.92) and during PACU stay (OR 0.87; 95% CI=0.77-0.97) compared to those who did not receive opioids. Moreover, iTEA on PACU arrival was a significant risk for severe pain at 30 minutes (adjusted OR 4.77; 95% CI=1.57-18.10). Conclusion: This study demonstrates a high incidence of iTEA immediately after surgery, and that intravenous opioid supplementation during and after surgery reduces the risk of iTEA. Lastly, iTEA on PACU arrival is a strong predictor of severe pain at discharge from PACU.