HOW DOES HEO2 INCREASE MAXIMUM EXPIRATORY FLOW IN HUMAN LUNGS
HOW DOES HEO2 INCREASE MAXIMUM EXPIRATORY FLOW IN HUMAN LUNGS
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DOI：
10.1172/jci109909
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发表时间：
1980-01-01
影响因子：
15.9
通讯作者：
WOOD, LDH
中科院分区：
文献类型：
--
作者：
MINK, SN;WOOD, LDH
逆行导管技术用于研究 HeO2 对肺泡和等压点 (EPP) 之间以及 EPP 和限流段 (FLS) 之间气道亚段最大呼气流量 (.ovrhdot.Vmax) 阻力的影响。在 6 个人离体肺中的空气和 HeO2 上，在亚肺叶支气管（内径 [内径]，0.54 ± 0.13 厘米）的同一气道部位发现了 FLS。两种气体的静态弹性反冲压力 (5 .+-. 1 cm H2O) 和 FLS 侧向压力（临界跨壁气道压力 -6 .+-. 3 cm H2O）没有差异。 .DELTA..ovrhdot.Vmax 平均为 37 .+-。 8.9%，与相似年龄的健康受试者（66±10 岁）中发现的值相似。 EPP 位于外周气道中的 HeO2 上（内径，0.33 .+-. 0.03 cm），空气上的 EPP 位于更下游。 EPP 和 FLS 之间的电阻高度依赖于密度。肺泡和 EPP 之间的阻力表现得好像与密度无关，部分原因是外周气道中的泊肃叶流，部分原因是 HeO2 导致外周气道随之变窄。外周气道中的这种与密度无关的行为使 HeO2 上的ΔVmax从其预测的最大量62%降低。假设 FLS 是阻塞点，这些发现与流量限制的波速理论一致，该理论经过修改，包括周围气道中与功能密度无关的压力损失。这些结果和结论与在活体狗身上发现的结果和结论相似。他们质疑先前将.DELTA..ovrhdot.Vmax 作为外周气道阻塞指标的解释，并证明了波速理论在解释呼气流量限制的复杂机制中的实用性。
The retrograde catheter technique was used to investigate the effect of HeO2 on resistance to maximum expiratory flow (.ovrhdot.Vmax) in airways subsegments between alveoli and the equal pressure point (EPP), and between EPP and the flow-limiting segment (FLS). FLS were found at the same airway site in sublobar bronchi (i.d. [inner diameter], 0.54 .+-. 0.13 cm) on both air and HeO2 in 6 human excised lungs. Static elastic recoil pressure (5 .+-. 1 cm H2O) and the lateral pressure at FLS (critical transmural airway pressure -6 .+-. 3 cm H2O) were not different on the 2 gases. .DELTA..ovrhdot.Vmax averaged 37 .+-. 8.9% and was similar to the value found in healthy subjects of similar age (66 .+-. 10 yr). EPP were located on HeO2 in peripheral airways (i.d., 0.33 .+-. 0.03 cm), and EPP on air were located more downstream. Resistance between EPP and FLS was highly density dependent. Resistance between alveoli and EPP behaved as if it were density independent, due in part to Poiseuille flow in the peripheral airways and in part to the consequent narrowing of peripheral airways on HeO2. This density-independent behavior in peripheral airways reduced .DELTA..ovrhdot.Vmax on HeO2 from its predicted maximal amount of 62%. Assuming that FLS is the choke point, these findings are consistent with wave-speed theory of flow limitation modified to include functionally density-independent pressure losses in peripheral airways. These results and conclusions are similar to those found in living dogs. They question previous interpretation of .DELTA..ovrhdot.Vmax as an index of peripheral airway obstruction, and demonstrate the utility of the wave-speed theory in explaining complicated mechanisms of expiratory flow limitation.