The acoustic reflection technique (AR), firstly used to detect the lowerairway, has been further developed since it was introduced to the upper airway assessment in 1980s.
声反射技术最早应用于下气道的检测，80年代始用于无创性上气道评估。
2
Results The pressure of airway after dripping was lower than the pressure before dripping (P<0.05), and lower than that of control group (P<0.05).
结果 用药后气道内压力值比用药前降低（P<0.05），也低于同时段的对照组（P<0.05）；
3
The upper and lower limits of an airway shall be also defined.