Methods:22 young healthy volunteers were enrolled in this study. Their heart rates,blood pressures,cardiac indexes were measured when they were ventilated on positive pressure(10/4 cmH 2O,20/10 cmH 2O)via mask or nasal mask.

• 方法 :对2 2例正常自愿者进行研究 ,测定正常人在不同压力水平 (10 /4cmH2 O、 2 0 /10cmH2 O)的通气状态时及通过鼻罩或口鼻面罩通气时的心率、血压、心脏指数。