Low dose fentanyl and propofol improve the speed and quality of tidal-breathing induction techniques in sevoflurane anesthesia for adults.

Abstract

The objective of this study was to investigate whether low dose fentanyl, with or without low dose propofol, as pretreatment agent/s is capable of speeding up and improving the quality of laryngeal mask airway (LMA) insertion in tidal-breathing induction technique with high-concentration sevoflurane. One hundred and twenty patients were assigned to one of the three groups: Group S, induction with 8% sevoflurane only; Group F + S, 1.0 microgram/kg fentanyl prior to induction; and Group F + P + S, 1.0 microgram/kg fentanyl and 0.5 mg/kg propofol prior to induction. It was demonstrated that the time from administration of drug (drugs) to loss of eyelash reflex (P < 0.05, Group F + P + S vs. F + S; P < 0.01, Group F + P + S vs. S), to jaw relaxation (P < 0.05, Group F + P + S vs. S) and time taken for LMA insertion (P < 0.01, Group F + P + S vs. S) were all shorter in Group F + P + S, with fewer complications (coughing and involuntary movement) during induction, however, the first time success rate with LMA insertion did not significantly differ among the comparing groups. According to a postoperative inquiry (by questionnaire), there were significantly more patients in the Group F + P + S (57.5%) who considered the induction as pleasant (P < 0.05), of whom 75% expressed that they would be willing to undergo an induction of the same form again in the future (P < 0.05). This more positive rating may be related to the mild sedative effects of the agents given and shorter induction time, which significantly helped reduce the rate of recall of the unpleasant gas. The results of this study of LMA insertion, for ASA I or II adult patients undergoing the tidal-breathing technique with 8% sevoflurane, suggest that pretreatment with 1 microgram/kg fentanyl plus 0.5 mg/kg propofol is superior in comparison with either pretreatment with 1 microgram/kg fentanyl or absence of pretreatment.