Alsosaturation impair time below 90%（SIT90%）were observed to time duration has big influence on clinical symptom.
Alsosaturation impair time below 90%（SIT90%）were observed to time duration has big influence on clinical symptom.
并观察血氧饱和度低于90%的时间占监测时间的百分比（satvation impair time below 90%，SIT 90%），其时间的长短对临床症状的影响的显著性。