Shepard J M, Gropper M A, Nicolaysen G, Staub N C, Bhattacharya J
Cardiovascular Research Institute, University of California, San Francisco 94143.
J Appl Physiol (1985). 1988 Feb;64(2):874-9. doi: 10.1152/jappl.1988.64.2.874.
We have micropunctured the lung in the open thorax of 17 anesthetized dogs to measure microvascular pressure. After intravenous pentobarbital sodium (25 mg/kg), we exposed the left lung through a wide left thoracotomy, which required rib excision. Through a double-lumen endotracheal tube, we ventilated the right lung to maintain normal blood gases and pH while we held the left lung motionless at an inflation pressure of 5 cmH2O. To reduce motion on the surface of the left lower lobe, we resected the left upper lobe, placed a Plexiglas baffle between the lobe and the heart, and held the lobe surface in a suction ring. In accordance with procedures we have previously described, we micropunctured subpleural vessels to measure microvascular pressure. At base line when alveolar pressure exceeded left atrial pressure (zone 2 conditions), 21, 38, and 41% of the total pressure drop occurred, respectively, in the arterial, microvascular, and venous segments. When we raised left atrial pressure above alveolar pressure (zone 3 conditions), the corresponding pressure drops were 30, 55, and 20% of total. The blood flow in the superficial layer of the lung averaged 15% less than the flow in the deeper layers as measured by distribution of 99mTc-albumin macroaggregates. We conclude that the intact and the isolated lung preparations in dog exhibit similar distributions of subpleural microvascular pressure.
我们在17只麻醉犬的开放胸腔内对肺进行了微穿刺以测量微血管压力。静脉注射戊巴比妥钠（25mg/kg）后，通过广泛的左胸廓切开术暴露左肺，这需要切除肋骨。通过双腔气管内导管对右肺进行通气以维持正常的血气和pH值，同时将左肺保持在5cmH₂O的充气压力下静止不动。为了减少左下叶表面的运动，我们切除了左上叶，在该叶与心脏之间放置了一个有机玻璃挡板，并将叶表面固定在一个吸引环中。按照我们之前描述的程序，我们对胸膜下血管进行微穿刺以测量微血管压力。在基线时，当肺泡压力超过左心房压力（2区条件）时，总压力降分别在动脉、微血管和静脉段中发生21%、38%和41%。当我们将左心房压力提高到高于肺泡压力（3区条件）时，相应的压力降分别占总压力降的30%、55%和20%。通过99mTc-白蛋白大聚合体的分布测量，肺表层的血流平均比深层血流少15%。我们得出结论，犬的完整肺和离体肺标本表现出相似的胸膜下微血管压力分布。
