Improved postoperative analgesia with isoflurane than with propofol anaesthesia

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.

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.

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%).

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