Allen S, Gabel J, Drake R
Center for Microvascular and Lymphatic Studies, University of Texas Medical School, Houston 77030.
Am J Physiol. 1989 Aug;257(2 Pt 2):H690-2. doi: 10.1152/ajpheart.1989.257.2.H690.
We studied the effect of left atrial pressure (LAP) elevation on the formation of pleural effusion in unanesthetized sheep. We prepared the animals by placing catheters in the left atrium, pulmonary artery, femoral artery, and vein. We also placed a balloon catheter in the left atrium. After a recovery period of at least 1 wk, we measured LAP, pulmonary artery pressure (PAP), systemic arterial pressure, systemic venous pressure, cardiac output, plasma protein concentration, and plasma colloid osmotic pressure (pi c). We calculated capillary pressure (Pc) as 0.5(PAP - LAP). We then elevated LAP such that Pc-pi c was between -10 and 19.5 mmHg for 6-24 h. At the end of the experiment, we killed the sheep and measured the volume and protein concentration of the right pleural effusion. We also determined the extravascular fluid to blood free dry weight of the right lung. We found that pleural effusions and pulmonary edema formed when Pc-pi c greater than 5 mmHg. We also found that the pleural effusion volume correlated with the amount of pulmonary edema. Our data show that elevated LAP may cause pleural effusions, but only after pulmonary edema has developed.
我们研究了左心房压力（LAP）升高对未麻醉绵羊胸腔积液形成的影响。我们通过将导管插入左心房、肺动脉、股动脉和静脉来准备实验动物。我们还在左心房放置了一个球囊导管。经过至少1周的恢复期后，我们测量了LAP、肺动脉压力（PAP）、体动脉压力、体静脉压力、心输出量、血浆蛋白浓度和血浆胶体渗透压（πc）。我们将毛细血管压力（Pc）计算为0.5（PAP - LAP）。然后我们升高LAP，使Pc - πc在-10至19.5 mmHg之间持续6至24小时。在实验结束时，我们处死绵羊并测量右侧胸腔积液的体积和蛋白浓度。我们还测定了右肺血管外液与无血干重的比值。我们发现当Pc - πc大于5 mmHg时会形成胸腔积液和肺水肿。我们还发现胸腔积液的体积与肺水肿的量相关。我们的数据表明，LAP升高可能导致胸腔积液，但仅在肺水肿发生之后。
