Lobar contribution to VA/Q inequality during constant-flow ventilation.
Lobar contribution to VA/Q inequality during constant-flow ventilation.
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恒流通气期间肺叶对 VA/Q 不平等的贡献。
DOI：
10.1152/jappl.1988.65.5.2132
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Sznajder,JI
中科院分区：
文献类型：
--
作者：
Schumacker,PT;Solway,J;Wood,LD;Sznajder,JI
先前的研究表明，麻醉犬在呼吸暂停期间，通过向主干支气管下方插管提供连续的吸入通气流，可以维持正常的动脉PCO 2，尽管与常规机械通气（IPPV）相比，这种恒流通气（CFV）也与通气-灌注（VA/Q）不平等的显著增加相关。可以想象，这种VA/Q的不平等可能是由于不均匀的通气分布引起的叶之间的VA/Q比的差异，即使个别叶是相对均匀的。或者，如果导致VA/Q不匹配的因素也存在于肺叶内，则VA/Q不平等可能发生在肺叶水平。在9只麻醉开胸犬上，应用多种惰性气体排除技术，比较了全肺和左下叶的气体交换效率。全肺和左下叶气体交换的测量允许比较叶内与叶间VA/Q不平等的程度。在呼气末正压IPPV期间，动脉PO 2和PCO 2（分别为183 +/- 41和34.3 +/- 3.1 Torr）与叶静脉PO 2和PCO 2（分别为172 +/- 64和35.7 +/- 4.1 Torr;吸入O2分数= 0.44 +/- 0.02）相似。转换为CFV（3 l.kg-1.min-1）降低了动脉PO 2（112 +/- 26 Torr，P小于0.001）和叶静脉PO 2（120 +/- 27 Torr，P小于0.01），但没有改变惰性气体测量的分流（P大于0.5）。（250字处删节）
Previous studies have shown that normal arterial PCO2 can be maintained during apnea in anesthetized dogs by delivering a continuous stream of inspired ventilation through cannulas aimed down the main stem bronchi, although this constant-flow ventilation (CFV) was also associated with a significant increase in ventilation-perfusion (VA/Q) inequality, compared with conventional mechanical ventilation (IPPV). Conceivably, this VA/Q inequality might result from differences in VA/Q ratios among lobes caused by nonuniform distribution of ventilation, even though individual lobes are relatively homogeneous. Alternatively, the VA/Q inequality may occur at a lobar level if those factors causing the VA/Q mismatch also existed within lobes. We compared the efficiency of gas exchange simultaneously in whole lung and left lower lobe by use of the multiple inert gas elimination technique in nine anesthetized open-chest dogs. Measurements of whole lung and left lower lobe gas exchange allowed comparison of the degree of VA/Q inequality within vs. among lobes. During IPPV with positive end-expiratory pressure, arterial PO2 and PCO2 (183 +/- 41 and 34.3 +/- 3.1 Torr, respectively) were similar to lobar venous PO2 and PCO2 (172 +/- 64 and 35.7 +/- 4.1 Torr, respectively; inspired O2 fraction = 0.44 +/- 0.02). Switching to CFV (3 l.kg-1.min-1) decreased arterial PO2 (112 +/- 26 Torr, P less than 0.001) and lobar venous PO2 (120 +/- 27 Torr, P less than 0.01) but did not change the shunt measured with inert gases (P greater than 0.5).(ABSTRACT TRUNCATED AT 250 WORDS)