Bidani A, Flumerfelt R W, Crandall E D
Respir Physiol. 1978 Oct;35(1):27-42. doi: 10.1016/0034-5687(78)90038-5.
Blood flow into the pulmonary capillaries and the volume of blood within the capillary bed are both pulsatile with the cardiac cycle. We have developed a quantitative model of diffusional gas exchange in the lung to investigate the effects of coupling between these two time-varying parameters on lung O2 and CO2 exchange. For normal man breathing room air at rest, the computed results agree well with previous predictions for the constant flow and volume case, and for the case of pulsatile flow alone. When coupled time-varying pulmonary capillary blood flow and volume are included, using the best data available in the literature to define these parameters, diffusional O2 exchange is improved over the cases of pulsatile flow or volume alone, and closely approximates that obtained for the hypothetical constant flow and volume case. CO2 exchanges, and O2 exchange during hypoxia, are not affected by pulsatile flow and/or volume. These results suggest that O2 exchange is efficient in the presence of coupled blood flow and blood volume pulsations as they exist in the lung capillaries, and that these conditions may be optimal for gas exchange under certain physiological (or pathological) conditions.
进入肺毛细血管的血流以及毛细血管床内的血量都随心动周期呈脉动变化。我们建立了一个肺内扩散性气体交换的定量模型，以研究这两个随时间变化的参数之间的耦合对肺内氧气和二氧化碳交换的影响。对于静息状态下呼吸室内空气的正常男性，计算结果与先前对恒定流量和容积情况以及仅脉动流情况的预测结果吻合良好。当纳入耦合的随时间变化的肺毛细血管血流和容积时，利用文献中可得的最佳数据来定义这些参数，扩散性氧气交换比仅脉动流或仅容积的情况有所改善，并且非常接近假设的恒定流量和容积情况下获得的结果。二氧化碳交换以及缺氧时的氧气交换不受脉动流和/或容积的影响。这些结果表明，在肺毛细血管中存在的耦合血流和血容量脉动情况下，氧气交换是有效的，并且这些条件在某些生理（或病理）条件下可能是气体交换的最佳条件。
