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 assessed in 24 healthy volunteers who participated on three occasions, receiving either intravenous (IV) F (2.4 microg/kg), M (36 microg/kg), or B (0.6 microg/kg F, 9 microg/kg M) 5 min before three vital capacity breaths of 8% S, 66% N2O, and O2. At loss of lid-lash reflex (LLR), ventilation was manually assisted until a randomly assigned time of administration was attained, at which time laryngoscopy and tracheal intubation were attempted. The effective times for 50% of subjects (ET50) to loss 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, and 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 in B, and greatest in M. The time to achieve good intubating and airway conditions up to intubation was lowest with M or B. Anesthetic adjuvants did not improve the time to achieve loss of consciousness with anesthetic induction via the face mask with sevoflurane, but they significantly decreased the time to acceptable tracheal intubating conditions.


CONCLUSIONS
Adults can be anesthetized with very few side effects by breathing themselves to sleep with sevoflurane. Giving patients small doses of sedatives intravenously before they inhale an anesthetic can improve the speed and quality of the process of falling asleep.
Muzi
M
M
Department of Anesthesiology, The Medical College of Wisconsin and Veterans Affairs Medical Center, Milwaukee 53295, USA.
Colinco
M D
MD
Robinson
B J
BJ
Ebert
T J
TJ
D000280:Administration, Inhalation; D000328:Adult; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D000768:Anesthesia, General / Q000379:methods*; D018685:Anesthetics, Inhalation; D001794:Blood Pressure / Q000187:drug effects; D004347:Drug Interactions; D004987:Ethers; D005260:Female; D005283:Fentanyl / Q000627:therapeutic use*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use*; D007442:Intubation, Intratracheal / Q000379:methods; D017214:Laryngeal Masks; D008297:Male; D008738:Methyl Ethers; D008874:Midazolam / Q000627:therapeutic use*; D011292:Premedication; D000077149:Sevoflurane
D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D004987:Ethers; D006993:Hypnotics and Sedatives; D008738:Methyl Ethers; D000077149:Sevoflurane; D008874:Midazolam; D005283:Fentanyl