Patient-controlled epidural analgesia: interactions between nalbuphine and hydromorphone

Epidural opioid analgesia can offer advantages over intravenous administration, however, opioid-related side effects are common after epidural administration. We studied the effect of adding nalbuphine (NB), an opioid agonist-antagonist, to hydromorphone (HM) for patient-controlled epidural analgesia (PCEA) in 78 healthy women after elective cesarean delivery. Patients were randomly assigned to one of four treatment groups. The control group received preservative-free HM (Dilaudid) alone, 0.075 mg/mL, while the three study groups received HM, 0.075 mg/mL, containing preservative-free NB (Nubain) 0.02, 0.04, or 0.08 mg/mL. Intraoperatively, all patients received epidural bupivacaine 0.5%. Postoperatively, a patient-controlled anesthesia (PCA) device was connected to the epidural catheter and programmed to deliver a 3-mL loading dose of the analgesic solution. Subsequently, patients could self-administer 2 mL bolus doses on demand with a 30-min lockout interval. Patients were encouraged to ambulate approximately 8 h after surgery, and PCEA therapy was discontinued when a clear liquid diet was tolerated. Visual analog scale scores were used to assess pain at 8-h intervals while using PCEA therapy. Although the overall incidences of nausea (19%-35%) and pruritus (32%-62%) were similar in all four groups, the addition of NB decreased the need for bladder catheterization. The highest NB concentration resulted in increased PCA demands during the 32-h study period. In conclusion, the combination of HM 0.075 mg/mL and NB 0.04 mg/mL resulted in lower nausea scores and a decreased incidence of urinary retention compared with HM alone, without increasing the opioid analgesic requirement.