Post-operative intravenous continuous analgesia: comparison of buprenorphine, fentanyl and nalbuphine.

Continuous intravenous infusions of fentanyl, buprenorphine or nalbuphine were investigated to provide pain relief for patients after major abdominal surgery. Buprenorphine (n = 23) was given as a loading dose of 5 micrograms kg-1 and infused at 0.8 micrograms kg-1 h-1. Fentanyl (n = 20) was given as a loading dose of 2 micrograms kg-1 and infused at 0.7 micrograms kg-1 h-1. Nalbuphine (n = 21) was given as a loading dose of 200 micrograms kg-1 and infused at 80 micrograms kg-1 h-1. The infusion rate was increased when analgesia was inadequate, and decreased if respiratory depression occurred. Mean doses were respectively 0.74 +/- 0.15 microgram kg-1 h-1 buprenorphine, 0.68 +/- 0.18 microgram kg-1 h-1 fentanyl, 83 +/- 21 micrograms kg-1 h-1 nalbuphine. Titration of continuous intravenous infusion of buprenorphine and fentanyl provided better analgesia than nalbuphine with smaller doses than those reported in similar studies allowing spontaneous breathing.