Postvoid Residuals Remain Unchanged in Patients With Postoperative Thoracic Epidural Analgesia After Thoracotomy

Background and Objectives: We found in previous studies that thoracic epidural analgesia (TEA) after open renal surgery via lumbotomy significantly impaired bladder function with decreased detrusor contractility and increased postvoid residuals under urodynamic assessment. Here we evaluated the effect of TEA on bladder emptying in patients undergoing thoracotomy. Methods: In a prospective, follow-up study, 13 men and 13 women with an International Prostate Symptom Score of less than 7 and with a postvoid residual of less than 100 mL underwent sonographic assessment of the postvoid residual the day before thoracotomy without TEA and 2 days postoperatively under TEA. The epidural catheter was inserted at level T4/5 or 5/6. Continuous epidural analgesia was maintained with a mixture of bupivacaine 1 mg/mL, epinephrine 2 mu g/mL, and fentanyl 2 mu g/mL. Primary outcome was the difference in postvoid residual before versus during TEA. Results: The postvoid residual did not change significantly preoperatively and postoperatively in men (P = 0.09) and women (P = 0.18). However, a significant decrease in bladder capacity at strong desire to void and voided volumes was observed in women. Of the 3 male patients with an initial International Prostate Symptom Score of 3 or greater and less than 7, all developed a postvoid residual of greater than 100 mL and were older than 50 years. Conclusions: Most patients after thoracotomy had unchanged postvoid residuals under TEA. Our study design does not allow us to determine cause and effect or to make conclusions that are based on comparative, randomized data. However, our observations do yield a hypothesis-generating basis for future clinical trials.