Low alfentanil target-concentrations improve hemodynamic and intubating conditions during induction with sevoflurane

To investigate the effects of different alfentanil target-concentrations on hemodynamics, respiration and conditions of tracheal intubation during an inhalation induction with 8% sevoflurane.

In this prospective randomized open-label study, 40 ASA I adult patients received alfentanil at the following target-concentrations: zero (Group 0), 25 (Group 25), 50 (Group 50) and 75 ng*mL(-1) (Group 75), starting five minutes before induction of anesthesia with 8% sevoflurane in 50% nitrous oxide. The ease of intubation was determined on fixed criteria and scored; arterial pressure, heart rate and bispectral index (BIS) were recorded at one-minute intervals.

Times to allow tracheal intubation were shortened only in Group 75 (94 +/- 8 sec) as compared to Group 0 (140 +/- 11 sec, P < 0.05). BIS values, tracheal intubation scores and number of attempts were not different between groups. However, more patients suffered from apnea in Group 75. Heart rate and mean arterial pressure remained stable in Group 75 whereas they increased significantly in the three other groups. No patient suffered hypotension.

Adding alfentanil at a 75 ng*mL(-1) target-concentration during an inhalation induction with 8% sevoflurane in 50% nitrous oxide allows intubation slightly earlier and provides stable hemodynamic conditions but the incidence of apnea during induction is higher. Lower concentrations are of little clinical interest.