Small risk of serious neurologic complications related to lumbar epidural catheter placement in anesthetized patients

Previous studies have identified pain during needle/catheter placement or during the injection of local anesthetic as a risk factor for the development of persistent paresthesias after regional anesthetic techniques. The performance of regional blockade on anesthetized patients theoretically increases the risk of postoperative neurologic complications, because these patients are unable to respond to painful stimuli. In this study, we evaluated the frequency of neurologic complications in 4298 thoracic surgical patients undergoing lumbar epidural catheter placement while under general anesthesia. Catheters were placed immediately after the induction and tracheal intubation or on completion of the surgical procedure, before emergence. Most epidural catheters (4220, or 98.2%) were used solely for postoperative analgesia; only 78 (1.8%) epidural catheters were used for intraoperative anesthesia. In 4239 (98.6%) patients, an opioid alone was administered. The remaining 56 (1.3%) patients received a local anesthetic or local anesthetic/opioid mixture epidurally. Analgesia was graded as excellent or good in 92.2% of patients. Side effects included sedation in 455 (10.6%), nausea or emesis in 328 (7.6%), pruritus in 116 (2.7%), and respiratory depression (pH less than or equal to7.3 and Paco(2) greater than or equal to50 mm Hg) in 308 (7.2%) patients. The mean duration of epidural analgesia was 2.4 +/- 0.8 days (range, 0-10.7 days). There were no neurologic complications, including spinal hematoma, epidural abscess or catheter site infections, radicular symptoms, or persistent paresthesias (95% confidence interval, 0%-0.08%). In one patient, the epidural catheter broke during removal, and a portion was retained. The patient was notified; no long-term sequelae were noted. Six patients developed new neurologic symptoms or postoperative worsening of a previous neurologic condition unrelated to epidural catheterization. We conclude that the risk of neurologic complications associated with lumbar epidural catheter placement in anesthetized patients is small. However, the relative risk of this practice, compared with epidural catheter placement in awake patients, is unknown.