Clinical Research Directory

Inclusion Criteria: * （1）Children aged 1 month to 12 years, （2） ASA Class I or II, （3）scheduled for surgery under general anesthesia Exclusion Criteria: -（1）Children and guardians declined to participate in the study (2) children with severe chronic respiratory, cardiovascular, central nervous system, liver and kidney diseases; (3) on the day of operation, the patients had active URTI and pulmonary infection, such as severe nasal obstruction, large amount of airway secretion, severe cough, fever (body temperature \> 37.5 ° C) , in addition to the above symptoms, signs of pulmonary consolidation and/or wet Rales, or peripheral white blood cells \> 10 × 109/L or \< 4 × 109/L with or without left shift of the nucleus, and chest X-ray showed new patchy, patchy infiltrative shadows or interstitial changes. (4) the child had severe anaphylaxis to narcotic drugs