Pulmonary edema and pleural effusions often compromise lung function in critically ill patients. These patients often have elevated pulmonary vascular pressures and elevated vena caval (central venous) pressures. It is well documented that elevated pulmonary vascular pressures cause edema and they may cause pleural effusions. Recent preliminary data indicate that 1) increased superior vena caval pressure may slow lymph flow from the lungs and pleural space and thus cause pleural effusions, 2) increased pulmonary vascular pressure and superior vena caval pressure have synergistic effects in producing edema and effusions and 3) the effects of increased pressures may be apparent only after several days of elevated pressures. This last point is important because many critically ill patients experience several days of increased pressures whereas most experiments to investigate edema and effusions have lasted only a few hrs. This proposal is to investigate the development of pulmonary edema and pleural effusions in unanesthetized sheep in which the left atrial pressure and/or superior vena caval pressure are elevated for up to 7 days. The left atrial pressure will be elevated with a balloon and the superior vena caval pressure will be elevated with a cuff around the vena cava. The amount of edema will be determined from the post mortem lung blood free wet and dry weights and the pleural effusion volume will be measured by aspirating the fluid from the pleural space. Experiments will also be performed to test the hypothesis that elevated vena caval pressure causes pleural effusions by slowing the flow of lymph from intrathoracic lymph nodes, and thus causing the lymph to leak from the nodes into the chest. Dye will be caused to flow into the large caudal mediastinal node of sheep and the node, the tissue surrounding the node and the pleural fluid will be examined for the presence of the dye. Additionally, the protein concentration of lymph flowing through nodes in the thorax will be compared to the protein concentration of pleural fluid. These studies valuable information about the roles of pulmonary vascular pressure and vena caval pressure in the development of pulmonary edema and pleural effusions.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08HL001999-04
Application #
3082422
Study Section
Special Emphasis Panel (SRC)
Project Start
1987-09-01
Project End
1992-08-31
Budget Start
1990-09-01
Budget End
1991-08-31
Support Year
4
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Texas Health Science Center Houston
Department
Type
Schools of Medicine
DUNS #
City
Houston
State
TX
Country
United States
Zip Code
77225
Stewart, Randolph H; Uray, Karen; Cox, Charles S et al. (2008) Myocardial fluid balance in dogs with naturally acquired heartworm infection. Am J Vet Res 69:356-61
Allen, S J; Fraser, R E; Laurent, U B et al. (1992) Turnover of hyaluronan in the rabbit pleural space. J Appl Physiol 73:1457-60
Laine, G A; Allen, S J (1991) Left ventricular myocardial edema. Lymph flow, interstitial fibrosis, and cardiac function. Circ Res 68:1713-21
Allen, S J; Gunnar Sedin, E; Jonzon, A et al. (1991) Lung hyaluronan during development: a quantitative and morphological study. Am J Physiol 260:H1449-54
Allen, S J; Drake, R E; Laine, G A et al. (1991) Effect of thoracic duct drainage on hydrostatic pulmonary edema and pleural effusion in sheep. J Appl Physiol 71:314-6
Butler, B D; Drake, R E; Sneider, W D et al. (1990) Changes in microvascular permeability with acceleration of edema in dog lungs. Am J Physiol 258:H395-9
Allen, S; Gabel, J; Drake, R (1989) Left atrial hypertension causes pleural effusion formation in unanesthetized sheep. Am J Physiol 257:H690-2