Pm'po~: In a randomized, double-blind clinical trial, we compared the postoperative analgesic effect and dose consumption of fentanyl after intraoperative high dose and low dose fentanyl administration. Methods: Sixty ASA class I to II female patients undergoing total abdominal hysterectomy CI-AH), were randomly allocated to receive either I Hg.kg -I (low dose group, n = 30) or 15 Hg.kg -a (high dose group, n = 30) fentanyl during induction of anesthesia. Anesthesia depth was maintained with inhalation of halothane in the low dose group, or combined with 100 Hg'hr -~ fentanyl iv in the high dose group. Postoperative pain was treated with an intravenous patient-controlled analgesia system and was assessed with a visual analog pain score at rest. R~ts: Patients in the high dose group had higher pain intensity at four and eight hours postoperatively, more fentanyl consumption and a greater incidence of emesis in the postoperative period of 16 hr than those in the low dose group (P < 0.05). Heart rate, blood pressure, and respiratory rate were similar between the two groups. C, oncJttdon: Our results suggest that acute fentanyl tolerance develops after administration of high dose fentanyl during surgery and, consequently, results in a higher postoperative pain intensity and greater fentanyl consumption. REsultats : Les patientes qui ont re~u la forte dose ont connu des douleurs plus intenses quatre et huit heures apr~s I'op&ation, ont pris davantage de fentanyl et ont eu une plus grande incidence de vomissements dans les 16 h qui ont suivi I'opEration, que celles qui ont re~u une faible dose (P < 0,05). La fr~quence cardiaque, la tension art&ielle et le rythme respiratoire n'ont pas pr&entd de diff&ence intergroupe. Conclusion : Les r&ultats sugg&ent qu'une tol&ance soudaine au fentanyl se ddveloppe aprEs l'administration peropEratoire d'une forte dose et qu'elle entra~ne, par consdquent, des douleurs postop&atoires plus intenses et une plus grande consommation de fentanyl.

The results suggested that postoperative pain was an associative risk factor to increase the incidence of emesis in these female patients.