THE EFFECTS OF PREMEDICATION ON INHALED INDUCTION OF ANESTHESIA WITH SEVOFLURANE

The effects of premedication with midazolam (M), fentanyl (F), or both (B) on induction of anesthesia via a mask with sevoflurane (S) were a ssessed in 24 healthy volunteers who participated on three occasions, receiving either intravenous (IV) F (2.4 mu g/kg), M (36 mu g/kg) or B (0.6 mu g/kg F, 9 mu g/kg M) 5 min before three vital capacity breath s of 8% S, 66% N2O, and O-2. At loss of lid-lash reflex (LLR), ventila tion was manually assisted until a randomly assigned time of administr ation was attained, at which time laryngoscopy and tracheal intubation were attempted. The effective times for 50% of subjects (ET50) to los s of LLR were 64 s for M and B and 54 s for F (P < 0.05). The ET50 to acceptable intubating conditions were 4.3, 3.1 and 2.5 min for F, M, a nd B, respectively. F resulted in more airway management difficulties than M or B. Heart rate was slightly increased before intubation in M. Heart rate increases after intubation were least in F, intermediate i n B, and greatest in M. The time to achieve good intubating and airway conditions up to intubation was lowest with M or B. Anesthetic adjuva nts did not improve the time to achieve loss of consciousness with ane sthetic induction via the face mask with sevoflurane, but they signifi cantly decreased the time to acceptable tracheal intubating conditions . Implications: Adults can be anesthetized with very few side effects by breathing themselves to sleep with sevoflurane. Giving patients sma ll doses of sedatives intravenously before they inhale an anesthetic c an improve the speed and quality of the process of falling asleep.