Bernard S L, Obermiller T, Polissar N L, Mendenhall J M, Butler J, Lakshminarayan S
Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle.
Microvasc Res. 1993 May;45(3):262-8. doi: 10.1006/mvre.1993.1023.
The systemic arterial blood supply to the lung (bronchial blood flow, Qbr) is commonly measured using the reference flow technique by injecting radiolabeled microspheres into the left atrium (LA) and simultaneously collecting a reference blood sample from a large artery such as the aorta. These measurements are often done with the pulmonary artery occluded prior to the time of injection. We have reported previously that left atrial blood refluxes up the pulmonary veins following pulmonary artery (PA) occlusion. We designed this experiment to determine if 15 mu microspheres reflux from the LA into the left lung (i) when the left PA is occluded prior to microsphere injection and (ii) when the left PA is open during the injection. We calculated Qbr to the left lung after simultaneous left ventricular (LV) and LA injections of different radiolabeled microspheres in anesthetized, closed-chest, prone goats. When the PA was open (but occluded 5 sec after the microsphere injection), Qbr calculated from an LA injection differed little from that calculated from an LV injection of microspheres. However, when the PA was occluded prior to injection of the microspheres, Qbr calculated from an LA injection was significantly higher than that calculated from an LV injection suggesting that microspheres reflux from the LA to the lung.
肺的体循环动脉血供（支气管血流，Qbr）通常采用参考流量技术进行测量，即通过将放射性标记的微球注入左心房（LA），并同时从诸如主动脉等大动脉采集参考血样。这些测量通常在注射前使肺动脉闭塞的情况下进行。我们之前曾报道，肺动脉（PA）闭塞后，左心房血液会沿肺静脉逆流。我们设计了这个实验，以确定在以下两种情况下，15微米的微球是否会从左心房逆流到左肺：（i）在微球注射前左肺动脉闭塞时；（ii）在注射过程中左肺动脉开放时。在麻醉、开胸、俯卧的山羊身上，同时向左心室（LV）和左心房注射不同放射性标记的微球后，我们计算了左肺的Qbr。当肺动脉开放时（但在微球注射后5秒闭塞），通过左心房注射计算出的Qbr与通过左心室注射微球计算出的Qbr差异不大。然而，当在微球注射前肺动脉闭塞时，通过左心房注射计算出的Qbr显著高于通过左心室注射计算出的Qbr，这表明微球从左心房逆流到了肺。
