Background: Nitrous oxide is decreasingly used due to 
theoretically considered complications. However, we have 
not had clinically obvious complications for many 
decades. The present study was done to investigate 
usefulness of nitrous oxide in sevoflurane anesthesia in 
terms of hemodynamic changes at induction and 
postoperative complications. 
Methods: One hundred and twenty patients for body 
surface surgery were enrolled. Anesthesia was induced 
with sevoflurane 5% for 5 min. or 8% for 3 min. with or 
without 50% nitrous oxide and maintained with 
sevoflurane with or without 50% nitrous oxide (5%GOS, 
8%GOS, 5%OS, and 8%OS groups, each 30 patients). 
Blood pressure, heart rate, loss of eyelash reflex and 
verbal response, sevoflurane consumption, time to 
emergence, and postoperative complications including 
nausea and vomiting were compared among the groups. 
8% OS than those in 5% GOS and 8% GOS, respectively. 
The frequency of nausea and vomit were not different 
among the groups. No clinically obvious complication was 
observed for postoperative one-month period. 
Conclusion: In sevoflurane anesthesia, nitrous oxide 
decreased hemodynamic changes at induction and 
intubation, and did not induce any clinically obvious 
complications. 
Keywords: Nitrous oxide; Sevoflurane; Hemodynamics; 
Complication 
*Corresponding
 Author:
 Tomoki
 Nishiyama,
Department of Anesthesiology, Shinagawa Shishokai 
Hospital, 1-29-7, Kita-shinagawa, Shinagawa-ku, Tokyo, 
140-0001, Japan; Tel: +81-3-5871-0700, E-mail: nishit
tky@umin.ac.jp  
Introduction 
Results: Time to loss of eyelash reflex and verbal 
response were significantly shorter in 5% GOS and 8% 
GOS than those in 5% OS and 8% OS, respectively. 
Sevoflurane consumption was significantly larger with 
5% OS than 5% GOS. Time to extubation was not 
different. Changes in blood pressure were significantly 
higher in 8% OS than that in 8% GOS. Increase in heart 
rate by intubation was significantly larger in 5% OS and 8% OS than those in 5% GOS and 8% GOS, respectively. 
The frequency of nausea and vomit were not different 
among the groups. No clinically obvious complication was 
observed for postoperative one-month period. 
Conclusion: In sevoflurane anesthesia, nitrous oxide 
decreased hemodynamic changes at induction and 
intubation, and did not induce any clinically obvious 
complications.