Background: Sevoflurane is almost the idealest volatile anesthetic agent regarding inhalation induction of general anesthesia. Previous studies have established a role of sevoflurane in high concentration primed in the circuit for inhalation induction in pediatric patients. However, which concentration of sevoflurane is suitable has not yet been reported. This study was designed to compare the efficiency of different concentration of sevoflurane i.e. 2%, 4%, 6%, and 8% and with N2O in 50% oxygen for induction of anesthesia in pediatric patients and at the same time to evaluate the tolerance of patients.
Methods: One hundred and twenty children who were 3 to 10 years old, of ASA class I, were randomly assigned to receive either 2%, 4%, 6%, and 8% sevoflurane and N2O in 50% O2 for induction of anesthesia. The time to loss of eyelash reflex, responses of airway reflex, involuntary movement, and hemodynamic responses were recorded.
Results: Ninety-nine children completed the study. The times to loss of eyelash reflex with 2% in sequence to 8% sevoflurane were 114 +/- 21 s, 87 +/- 11 s, 75 +/- 6 s, and 48 +/- 8 s respectively. Incidence of airway reflex response including coughing, laryngospasm, and breath holding was the highest in the 8% group (P < 0.05). Inhalation induction with sevoflurane significantly decreased systolic as well as diastolic blood pressure compared with baseline blood pressure in all the four groups. The extent of decrease of blood pressure was within 20% range of baseline blood pressure in all groups. Significant increase of heart rate was only observed in the 4% and 6% groups.
Conclusions: Sevoflurane 6% for inhalation induction apparently caused low incidence of adverse effects and hastened induction. We suggest that 6% sevoflurene is a concentration more practical for inhalation induction in pediatric patients.