The changes of the PO2 were similar to the PaO2/FiO2. The PCO2and the Cst,rs did not differ significantly between the prone position and the supine position in the two groups.

• 两组PaO2变化趋势与PaO2/FiO2相同。 两组PaCO2及呼吸系统静态顺应性(Cst；rs)在俯卧位通气前后差异无显著性(P>0.；05)。