Edema caused by continuous epidural hydromorphone infusion: a case report and review of the literature.

Background: Intraspinal drug delivery (IDD) therapy has been increasingly employed in patients with intractable, nonmalignant pain. Before implantation of permanent intraspinal pump, an intraspinal opioid screening trial is conducted to demonstrate the efficacy. The patient-controlled continuous epidural opioid infusion trail, performed in an outpatient setting, is widely accepted by many interventional pain specialists.
Objective: To report a case of severe edema observed during the continuous epidural hydromorphone infusion trial.
Case Report: An otherwise healthy 68-year-old lady with a 5-year history of severe low back pain and bilateral leg pain because of failed back surgery syndrome was referred to our clinic for IDD therapy. A tunneled lumbar epidural catheter was placed at L2-L3 with catheter tip advanced to L1 under fluoroscopic guidance. Satisfactory catheter placement was confirmed by epidurogram. The catheter was then tunneled subcutaneously and connected to a Microject patient-controlled epidural analgesia (PCEA) pump (Codman, Raynham, MA). The pump was programmed to deliver hydromorphone (0.1 mg/ml) at basal rate of 0.3 ml/h. The bolus dose was 0.1 ml with a 60-minute lockout interval. The patient was instructed how to operate the infusion pump. During the following infusion trial, she reported satisfactory analgesia (> 70 percent pain reduction) and was able to wean off her other systemic opioids. However, she developed diffuse edema and gained over 16 pounds during the 5-day infusion trial. Her edema finally resolved 3-4 days after termination of the epidural infusion.
Conclusion: Edema may occur and persist during epidural hydromorphone infusion. This report represents the first case report, to the best of our knowledge, describing severe edema in a patient on continuous epidural hydromorphone administration during an outpatient epidural infusion trial.