Joyce C J, Williams A B
Department of Intensive Care, Princess Alexandra Hospital, Brisbane, Australia 4102.
J Appl Physiol (1985). 1999 Apr;86(4):1116-25. doi: 10.1152/jappl.1999.86.4.1116.
Recent computed tomography studies show that inspired gas composition affects the development of anesthesia-related atelectasis. This suggests that gas absorption plays an important role in the genesis of the atelectasis. A mathematical model was developed that combined models of gas exchange from an ideal lung compartment, peripheral gas exchange, and gas uptake from a closed collapsible cavity. It was assumed that, initially, the lung functioned as an ideal lung compartment but that, with induction of anesthesia, the airways to dependent areas of lung closed and these areas of lung behaved as a closed collapsible cavity. The main parameter of interest was the time the unventilated area of lung took to collapse; the effects of preoxygenation and of different inspired gas mixtures during anesthesia were examined. Preoxygenation increased the rate of gas uptake from the unventilated area of lung and was the most important determinant of the time to collapse. Increasing the inspired O2 fraction during anesthesia reduced the time to collapse. Which inert gas (N2 or N2O) was breathed during anesthesia had minimal effect on the time to collapse.
近期的计算机断层扫描研究表明，吸入气体成分会影响麻醉相关肺不张的发展。这表明气体吸收在肺不张的发生过程中起重要作用。我们建立了一个数学模型，该模型结合了理想肺单元的气体交换模型、外周气体交换模型以及来自封闭可塌陷腔隙的气体摄取模型。假设最初肺作为理想肺单元发挥功能，但在麻醉诱导后，肺低垂部位的气道关闭，这些肺区域表现为封闭的可塌陷腔隙。主要关注的参数是肺未通气区域塌陷所需的时间；研究了预给氧以及麻醉期间不同吸入气体混合物的影响。预给氧增加了肺未通气区域的气体摄取速率，并且是塌陷时间的最重要决定因素。麻醉期间增加吸入氧分数可缩短塌陷时间。麻醉期间吸入哪种惰性气体（氮气或氧化亚氮）对塌陷时间的影响极小。
