Improved postoperative analgesia with isoflurane than with propofol anaesthesia.

Purpose: The impact of hypnotic drugs on postoperative analgesia has not been evaluated. We compared the influence of the maintenance of anaesthesia with either propofol or isoflurane on postoperative pain.

Methods: Forty ASA 1-2 women, undergoing cosmetic abdominoplasty were randomized to receive either 6-12 mg.kg-1.hr-1 propofol i.v. (P, n = 20) or MAC 1-1.5 isoflurane inhalation (Iso, n = 20). The lungs were ventilated with N2O 60% and O2 40%, and 1 microgram.kg-1 fentanyl i.v. provided intraoperative analgesia. Before surgical closure, 2 g propacetamol i.v. were administered. Postoperative analgesia was provided after hourly assessment of pain (VAS 0-100 mm), with 10 mg nalbuphine i.v. if VAS > or = 50 mm, during the eight hours after surgery. Sedation score (awake 0 to unrousable 4) was also recorded. Analgesia satisfaction score (nil 0 to excellent 4) obtained from the patient on discharge.

Results: Sedation scores were similar in both groups except in the first postoperative hour, when it was higher in the Iso group. The VAS at rest (15.4 +/- 18.6 vs 29.7 +/- 19.8 mm, P = 0.0001) and nalbuphine requirements (0.13 +/- 0.35 vs 0.70 +/- 0.80 doses, P = 0.004) were lower in the Iso group during the first six hours, although emesis was more frequent than in P (60 vs 25%; P = 0.03). The incidence of analgesia satisfaction score (> or = 3) was similar between the two groups (P: 95; Iso: 75%).

Conclusion: These results suggested that isoflurane anaesthesia provides better analgesia than propofol anaesthesia in the first six hours after abdominoplasty.