Nitrous oxide does not improve sevoflurane induction of anesthesia in adults.
OBJECTIVE
To compare the characteristics of sevoflurane induction with and without the addition of nitrous oxide (N(2)O) using tidal breathing inhalation induction without priming of the breathing circuit.


METHODS
Randomized, double-blind study.


METHODS
Operating rooms of an ambulatory surgery suite at a university hospital.


METHODS
60 ASA physical status I and II adult patients undergoing elective surgery.


METHODS
Patients were randomized into two groups. During induction, Group 1 received 8% sevoflurane in N(2)O 4L/min and oxygen (O(2)) 2L/min; Group 2 received 8% sevoflurane in O(2) 6L/min. The time to cessation of finger tapping was used as the main index for induction time. Any adverse effects such as coughing, apnea, excessive oral secretions, laryngospasm, excitatory movements, and hemodynamic changes were also noted.


RESULTS
There were no significant differences in the induction times (Group 1: 62.0 vs. Group 2: 60.0 sec), number of breaths taken to this time (15.0 vs. 14.0), expired sevoflurane concentration at this time (3.4 vs. 3.2%), and time to Laryngeal Mask Airway insertion (160.0 vs. 195.0 sec). The frequencies of induction-related adverse events were similar in both study groups.


CONCLUSIONS
The addition of N(2)O does not confer any clinically significant advantage in this method of sevoflurane induction in adults.
Siau
C
C
Department of Anesthesia, National University Hospital, Singapore.
Liu
E H C
EH
D000328:Adult; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage*; D009609:Nitrous Oxide / Q000008:administration & dosage*; D000077149:Sevoflurane; D013997:Time Factors
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D009609:Nitrous Oxide