Allen S J, Laine G A, Drake R E, Gabel J C
Center for Microvascular and Lymphatic Studies, University of Texas Medical School at Houston 77030.
Am J Physiol. 1988 Sep;255(3 Pt 2):H492-5. doi: 10.1152/ajpheart.1988.255.3.H492.
The effect of superior vena caval pressure (SVCP) elevation on the formation of pleural effusions (PE) was studied in sheep. Through a right thoracotomy, a Silastic cuff was placed around the superior vena cava. Catheters for monitoring SVCP and pulmonary artery pressure (PAP) were also placed. After a 1- to 3-wk recovery period, we measured the SVCP, PAP, cardiac output, and plasma protein concentration (Cp). We then elevated the SVCP to various levels from base line [5.3 +/- 2.6 (SD) mmHg] to 33 mmHg. The cardiac output, PAP, and Cp were remeasured 1-2 h and 24 h after SVCP elevation. At the end of the 24-h period, the animals were killed. The PE volume and pleural fluid protein concentration (Cpl) were measured, and the Cpl/Cp was calculated. PE generally did not occur until the SVCP was elevated above 15 mmHg. To study the effect of the thoracotomy on the subsequent pleural effusion, we studied six additional sheep in which we did not perform a thoracotomy. In these animals, the SVCP was elevated to between 5 and 28 mmHg for 24 h by use of a 16-Fr balloon catheter placed via a left external jugular vein and a right carotid-external jugular shunt. We found that the PE volume, for a given SVCP elevation, was similar to that present in sheep that received a thoracotomy. For all sheep the volume of PE was related to SVCP by the equation PE (ml) = 0.24e0.26SVCP, r = 0.85. In the sheep without a thoracotomy, Cpl/Cp rose with increasing volume of PE. Our data demonstrate that elevation of SVCP greater than 15 mmHg for 24 h results in the formation of PE. The rise in Cpl/Cp with PE volume suggests that filtration through the pleural vessels is not the major contributor to PE formation.
在绵羊身上研究了上腔静脉压（SVCP）升高对胸腔积液（PE）形成的影响。通过右胸切开术，在上腔静脉周围放置一个硅橡胶套。还放置了用于监测SVCP和肺动脉压（PAP）的导管。在1至3周的恢复期后，我们测量了SVCP、PAP、心输出量和血浆蛋白浓度（Cp）。然后将SVCP从基线水平[5.3±2.6（标准差）mmHg]升高到33 mmHg的不同水平。在SVCP升高后1至2小时和24小时重新测量心输出量、PAP和Cp。在24小时结束时，处死动物。测量PE体积和胸腔积液蛋白浓度（Cpl），并计算Cpl/Cp。通常直到SVCP升高到15 mmHg以上才会出现PE。为了研究胸切开术对随后胸腔积液的影响，我们另外研究了六只未进行胸切开术的绵羊。在这些动物中，通过经左颈外静脉放置的16F球囊导管和右颈动脉-颈外静脉分流术，将SVCP升高到5至28 mmHg并维持24小时。我们发现，对于给定的SVCP升高，PE体积与接受胸切开术的绵羊相似。对于所有绵羊，PE体积与SVCP的关系由方程PE（ml）=0.24e0.26SVCP表示，r = 0.85。在未进行胸切开术的绵羊中，Cpl/Cp随着PE体积的增加而升高。我们的数据表明，SVCP升高超过15 mmHg持续24小时会导致PE形成。Cpl/Cp随PE体积的升高表明，通过胸膜血管的滤过不是PE形成的主要因素。
