呼吸功能不全以严重的肺内通气-血液灌流比例(V_A/Q)失调为其特征,临床上表现为动脉氧合受到限制和/或二氧化碳清除受到破坏。近几年来,一些研究运用MIGET(惰性气体清除技术)得出不同全麻时的通气-血流比例失调,而借助MIGET方法对急性呼吸功能不全的重症病人的V_A/Q比例失调的研究则很少。所以,本研究的目的是,精确了解不同 Respiratory insufficiency is characterized by a severe pulmonary ventilation-hemoperfusion (V_A / Q) imbalance, which is clinically manifested as limited arterial oxygenation and / or destruction of carbon dioxide clearance. In recent years, some studies have used MIGET (inert gas scavenging technique) to derive different ventilatory-blood flow imbalances in different general anesthesia. However, studies on the V_A / Q imbalance in critically ill patients with acute respiratory insufficiency using MIGET less. Therefore, the purpose of this study is to understand exactly what is different