Effects of fentanyl administration before induction of anesthesia and placement of the Laryngeal Mask Airway: a randomized, placebo-controlled trial

Abstract

Study objective: To assess the effects of fentanyl administered before induction of anesthesia on movement and airway responses during desflurane anesthesia via the Laryngeal Mask Airway (LMA).

Design: Randomized, double-blinded, controlled trial.

Study setting: Tertiary-care academic center.

Patients: 100 adult, ASA physical status 1, 2, and 3 patients undergoing ambulatory surgery.

Interventions: Patients were administered fentanyl 1 μg/kg (n=51) or saline (n=49) 3 to 5 minutes before induction with propofol 2-2.5 mg/kg intravenously (IV), followed by LMA placement. Anesthesia was maintained with desflurane titrated to a bispectral index (BIS) of 50-60 and 50% nitrous oxide in oxygen, and fentanyl 25 μg boluses were titrated to respiratory rate.

Measurements: Apnea occurrence and duration of manual ventilation, as well as frequency and severity of movement, coughing, breath holding, and laryngospasm were recorded.

Main results: Two patients in each group were excluded from analysis. The fentanyl pretreatment group had a higher frequency of apnea (94% vs 64%; P=0.0003) and longer duration of manual ventilation (3 [interquartile range (IQR), 1.5-5] min vs 1 [0-1.5] min; P<0.0001) at induction. In contrast, the fentanyl pretreatment group had a lower frequency of movements (16% vs 51%;P=0.0001). The rates of intraoperative breath holding (6.1% vs 8.5%) and laryngospasm (2% vs 4.3%) in the two groups were similar. All subjects experiencing laryngospasm were smokers. Adjusting for smoking status did not affect the differences noted in apnea, duration of manual ventilation, or movement between groups; however, coughing occurrence was statistically higher in the placebo group (P=0.043).

Conclusions: Preinduction fentanyl increased the frequency of apnea at induction and duration of manual ventilation, but reduced the frequency of movements. In addition, it reduced intraoperative coughing in smokers.

Keywords: Airway responses; Desflurane; Fentanyl pretreatment; Laryngeal Mask Airway.