title: [Residual analgesic effect of fentanyl in patients undergoing myocardial revascularization with cardiopulmonary bypass.].
abstract: OBJECTIVE
  In spite of the frequent use of high doses of fentanyl for major surgeries, the correlation of its residual plasma concentration to postoperative analgesia deserves further investigation. This study aimed at evaluating the residual analgesic effect of fentanyl in the first and second postoperative days of myocardial revascularization, as well as quantifying its concentration.
  
  
  METHODS
  Participated in this study 11 patients undergoing myocardial revascularization with cardiopulmonary bypass under general anesthesia with 50 microg.kg-1 intravenous fentanyl. Analgesia was evaluated by a numeric verbal scale at moments zero (extubation), 70 min, 3, 5, 8 and 12 hours in the first day; and moments zero (24 h after extubation), 70 min, 3, 5, 8 and 12 hours in second post-operative day. Pain intensity to vigorous cough and respiratory physical therapy was evaluated. At every measurement, patients were asked about the need for analgesic complementation. Plasma samples were collected in moments zero (extubation), 70 min, 3, 5, 8 and 12 hours during the first and second postoperative days for fentanyl radioimmunoassay.
  
  
  RESULTS
  Mean pain intensity varied from 1.9 to 3.7 in the first day and from 2.1 to 3.8 in the second postoperative day. Fentanyl plasma levels (> 1 ng/ml) evidenced its contribution to post-operative analgesia during the first postoperative day.
  
  
  CONCLUSIONS
  In spite of the lack of correlation between residual fentanyl plasma concentration and pain intensity, patients referred only mild pain during the whole investigation period.
authors.affiliation: UNIFESP, São Paulo, SP.
authors.forename: Adriana Machado
authors.initials: AM
authors.lastname: Issy
authors.forename: Eloísa Bonetti
authors.initials: EB
authors.lastname: Espada
authors.forename: Rioko Kimiko
authors.initials: RK
authors.lastname: Sakata
authors.forename: Vera Lúcia
authors.initials: VL
authors.lastname: Lanchote
authors.forename: José Otávio Costa
authors.initials: JO
authors.lastname: Auler Júnior
authors.forename: Silvia Regina C J
authors.initials: SR
authors.lastname: Santos