Waaler B A, Aarseth P
Ciba Found Symp. 1976(38):65-76. doi: 10.1002/9780470720202.ch5.
Alterations in extravascular lung water content when capillary pressure or plasma colloid osmotic pressure is increased have been evaluated in isolated, continuously weighed, plasma-perfused pairs of rabbit lungs. After modest increases in left atrial pressure, most preparations rapidly reached a new stable weight, and thus a new transcapillary fluid balance, but no significant increase in extravascular lung water content could be detected. In preparations where there was still a steady, slow gain in weight and thus still some transvascular filtration of fluid 15 min after the increase in pressure, a moderate but significant increase in extravascular water could be detected. It is concluded that only very small transvascular shifts of fluid occur in the lungs when capillary pressure changes, as long as this change is kept below the level that causes oedema. This limitation of pressure-induced transvascular shifts of fluid in the lung could be explained by the existence, close to the capillaries, of a small interstitial space containing fluid with a high protein concentration. Alterations in the colloid osmotic pressure exerted by this fluid would then contribute markedly towards continuous readjustment of the transcapillary fluid balance in the lung. Experiments by other workers indicate that alveolar pressure can markedly affect the transcapillary fluid balance of the isolated perfused lung.
在对离体的、持续称重的、血浆灌注的兔肺对进行的实验中，研究了毛细血管压力或血浆胶体渗透压升高时血管外肺水含量的变化。在左心房压力适度升高后，大多数标本迅速达到新的稳定重量，从而建立了新的跨毛细血管液体平衡，但未检测到血管外肺水含量有显著增加。在压力升高15分钟后仍有稳定、缓慢的重量增加，即仍有一些液体经血管滤过的标本中，可检测到血管外水有中度但显著的增加。得出的结论是，只要毛细血管压力的变化保持在引起水肿的水平以下，当毛细血管压力改变时，肺中只会发生非常小的液体经血管转移。肺中压力诱导的液体经血管转移的这种限制可以用靠近毛细血管处存在一个小的间质间隙来解释，该间隙含有高蛋白浓度的液体。这种液体施加的胶体渗透压的变化将对肺中跨毛细血管液体平衡的持续重新调整有显著贡献。其他研究人员的实验表明，肺泡压力可显著影响离体灌注肺的跨毛细血管液体平衡。
