[Accidental subdural catheterization discovered after postoperative respiratory depression].

A 65-year-old man scheduled for gastrectomy was anesthetized with nitrous oxide combined with continuous epidural lidocaine. At the end of the operation, morphine 2 mg diluted in 0.25% bupivacaine 5 ml was injected through the epidural catheter. Seventy minutes later, the patient developed life-threatening respiratory depression which was antagonized by naloxone. The patient requested no analgesic during the first 26 postoperative hours. The respiratory depression in this patient was assumed to be caused by epidural morphine. Then subdural catheterization was confirmed radiologically. This was discovered to have resulted from migration of the epidural catheter into the subdural space. Subdural injection of morphine may have resulted in higher cerebrospinal fluid levels than the levels obtained after epidural injection. Subdural catheterization is a complication of epidural anesthesia that probably occurs more frequently than previously recognized. In postoperative patients receiving epidural morphine, their respiratory status should be monitored closely for hours.