The authors investigated the effect of Ptp on extravascular fluid formation in five isolated dog left lower lobes perfused at constant pulmonary artery (Ppa) and pulmonary venous (Ppv) pressures. In the control state Ppa was kept at 15-19 mmHg relative to the bottom of the lobe, Ppv at 0 to -1.5 mmHg, and mean Ptp at 7-10 cm H2O. The lobes were ventilated with 100% O2, perfused with warmed autologous blood, which was partially equilibrated with 95% N2 and 5% CO2. After a control period of 15 min with no weight gain, Ppv was increased to 10-14 mmHg by raising the level of the outflow drainage tube, and Ppa was raised to 24-27 mmHg by increasing flow. These pressures were then held constant for the remainder of the experiment. Following the increase in vascular pressures, the lung weight increased rapidly, primarily due to the increase in vascular volume, and then a slower steady weight gain occurred which averaged 0.90 gm/min/100 gm initial wet weight, and which the authors assumed to be the result of extravascular fluid accumulation. Mean Ptp was then increased in steps by increasing end expiratory pressure. The slower steady rate of weight gain was measured at each level of mean Ptp. For each cm H2O increase in mean Ptp the authors found an average decrease in rate of weight gain of 0.05 gm/min/100 gm initial wet weight (r=0.7).
|Original language||English (US)|
|State||Published - Jan 1 1976|
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