Lamm W J, Kirk K R, Hanson W L, Wagner W W, Albert R K
Medical Service, Veterans Administration Medical Center, Seattle, Washington.
J Appl Physiol (1985). 1991 Apr;70(4):1518-23. doi: 10.1152/jappl.1991.70.4.1518.
We have previously observed flows equivalent to 15% of the resting cardiac output of rabbits occurring through isolated lungs that were completely in zone 1. To distinguish between alveolar corner vessels and alveolar septal vessels as a possible zone 1 pathway, we made in vivo microscopic observations of the subpleural alveolar capillaries in five anesthetized dogs. Videomicroscopic recordings were made via a transparent thoracic window with the animal in the right lateral position. From recordings of the uppermost surface of the left lung, alveolar septal and corner vessels were classified depending on whether they were located within or between alveoli, respectively. Observations were made with various levels of positive end-expiratory pressure (PEEP) applied only to the left lung via a double-lumen endotracheal tube. Consistent with convention, flow through septal vessels stopped when PEEP was raised to the mean pulmonary arterial pressure (the zone 1-zone 2 border). However, flow through alveolar corner vessels continued until PEEP was 8-16 cmH2O greater than mean pulmonary arterial pressure (8-16 cm into zone 1). These direct observations support the idea that alveolar corner vessels rather than patent septal vessels provide the pathway for blood flow under zone 1 conditions.
我们之前观察到，在完全处于1区的离体兔肺中，出现了相当于兔静息心输出量15%的血流。为了区分肺泡角血管和肺泡间隔血管作为可能的1区血流途径，我们对五只麻醉犬的胸膜下肺泡毛细血管进行了体内显微镜观察。通过右侧卧位动物的透明胸窗进行视频显微镜记录。从左肺最上表面的记录中，肺泡间隔血管和角血管分别根据其位于肺泡内还是肺泡之间进行分类。通过双腔气管导管仅对左肺施加不同水平的呼气末正压（PEEP）进行观察。与传统观点一致，当PEEP升高到平均肺动脉压（1区-2区边界）时，通过间隔血管的血流停止。然而，通过肺泡角血管的血流持续存在，直到PEEP比平均肺动脉压高8 - 16 cmH₂O（进入1区8 - 16 cm）。这些直接观察结果支持了这样一种观点，即在1区条件下，是肺泡角血管而非开放的间隔血管为血流提供了途径。
