We studied the effects of continuous intravenous air embolization on lung fluid balance in unanesthetized sheep. Following a 2-h base line, we infused 300-micrometers-diam air bubbles into the pulmonary artery at a rate sufficient to increase pulmonary vascular resistance by 60-300% and for periods of 0.25-3 h. Air emboli produced a dose- and duration-dependent increase in lung lymph and protein flow due mainly to an increase in endothelial barrier permeability but also to elevated pressure in the over-perfused microcirculation. When we stopped the air infusion, the vascular resistance fell as the air emboli were reabsorbed. Lung lymph and protein flow increased further and then returned slowly to base line with a half-time proportional to the duration of embolization. Increasing left atrial pressure during air embolization caused an increase in lymph flow and protein clearance and an average decrease of 15 Torr in arterial O2 tension, all changes in excess of that caused by either increased pressure or air emboli alone.
SUMMARY We studied steady state transvascular fluid and protein exchange after uneven obstruction of the pulmonary arteries. In anesthetized sheep, ventilated by positive pressure, we measured pulmonary artery and left atrial pressures, cardiac output, lung lymph flow, and lymph/plasma protein ratios. We calculated pulmonary vascular resistance. In 16 sheep we obstructed the pulmonary arteries with various microemboli or balloons in lobar arteries until pulmonary vascular resistance was 2-3 times baseline. In every experiment, lung lymph flow increased as pulmonary vascular resistance increased. The lymph/plasma protein ratio did not change. In four sheep, we increased left atrial pressure by balloon obstruction of the mitral orifice. Pulmonary artery pressure increased as much as in the embolization experiments and lymph flow increased but the lymph/plasma protein ratio decreased, meaning that the increased fluid and protein flux after embolization cannot be due to high pulmonary artery or pulmonary venous outflow pressures alone. In four sheep we compared obstruction of the lower lobe pulmonary arteries by balloons with that of upper lobe pulmonary arteries. Lower lobe arterial obstruction caused the lymph flow which drains predominantly from the lower lobes to decrease whereas upper lobe artery obstruction increased lymph flow. This means that the increased fluid and protein flux occurred mainly in the open, perfused portion of the microvascular bed. The mechanism of the increased fluid filtration and protein permeability may be related to high vascular pressure and high linear blood flow velocity through a markedly restricted microvascular bed, although release of substances that affect endothelial permeability is not ruled out.IN THE ADULT respiratory distress syndrome, 1 a central feature is the occurrence of interstitial and alveolar edema. Since in pathological sections the edema fluid stains similarly to blood plasma (proteinaceous) and since there are often hyaline membranes in the air spaces, the edema is considered to be of the increased microvascular permeability variety.2 Hemodynamically, features commonly noted are an increase in pulmonary arterial pressure in the face of a normal pulmonary artery wedge pressure or a directly measured left atrial pressure. The calculated pulmonary vascular resistance is elevated. Numerous investigators 3 " 5 have frequently found plugging of pulmonary small arteries and microvessels by various types of microemboli.How is it that obstruction of pulmonary arteries causes pulmonary edema due to increased microvascular permeability? Gibbon and Gibbon 6 made one of the earliest observations on this syndrome. They found that resection of 70% of the lung mass in cats was followed by the development of pulmonary edema, especially if the resection was accompanied by infusions of whole blood or plasma. Although they believed the edema was due to the high pressure in the microvessels, they did suggest that the edema fluid was only slightly diluted plasma (that is, typical of...
This report provides the first evidence that expression levels of p120 in tumor tissues can be used as an independent and powerful prognostic marker for resected lung adenocarcinoma.
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