Lumbar epidural morphine infusions for children undergoing cardiac surgery

Objective: To determine whether outcomes and costs in children undergoing cardiac surgery are affected by the method of postoperative pain management. Design: Retrospective, case control. Setting: Tertiary care children's hospital in a university setting. Participants: Two groups of children undergoing cardiac surgery for palliation or repair of congenital heart disease over a 21-month period between January 1993 and September 1994. Interventions: Lumbar epidural morphine infusions (LEM) in one group, and IV opioid (IVO) medication in the other for postoperative pain control. Measurements and Main Results: Hospital courses of 27 LEM patients and 27 IVO patients were analyzed. In LEM patients, epidural catheters were placed following anesthetic induction, but before anticoagulation. A bolus of 50 μg/kg of preservative-free morphine sulfate was administered through the catheter, followed by a continuous infusion at 3 to 4 μg/kg/h for 22 to 102 (median, 46) hours postoperatively. The IVO patients received 50 μg/kg, IV, of fentanyl before incision followed by a continuous infusion at 0.3 μg/kg/min. The fentanyl infusion rate was decreased to 0.1 μg/kg/min postoperatively and maintained for 24 hours. Although the LEM group was demographically similar to the IVO group, times to tracheal extubation, transfer from the intensive care unit, and resumption of regular diet were significantly shorter in LEM patients. LEM and IVO patients received similar amounts of fentanyl during surgery (10.4 ± 19.3 μg/kg/h v 13.7 ± 8.1 μg/kg/h, p = 0.4). However, during postoperative recovery, LEM patients who were extubated late received significantly less supplemental opioid medication than IVO patients extubated late during the first 5 postoperative days. No complications related to dural puncture, bleeding into the epidural space, or respiratory depression were encountered. Pruritus and nausea/vomiting were the most commonly reported morbidities in both groups. Fifty-six percent (15/27) of LEM patients and 41% of IVO patients reported pruritus (p = 0.4). There was no significant difference in the incidence of nausea and vomiting between the groups (34% v 30%, respectively). Conclusions: Given the present methodologic limitations, the authors found improved outcomes only in LEM patients extubated late compared with IVO patients. Randomized, prospective studies to evaluate this conclusion and to determine the comparative efficacy and safety of LEM infusions are in progress.