Measurement of the extravascular water space in the lungs: Its dependence on alveolar blood flow

• Published in: Microvascular research Vol. 15; no. 2; pp. 149 - 167
• Main Authors: Goresky, Carl A., Warnica, J.Wayne, Burgess, John H., Cronin, Robert F.P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.1978
• Subjects: Animals; Cardiac Output; Dogs; Extracellular Space - physiology; Humans; Indicator Dilution Techniques; Models, Biological; Physical Exertion; Pulmonary Alveoli - blood supply; Pulmonary Alveoli - physiology; Regional Blood Flow; Rest
• ISSN: 0026-2862; 1095-9319
• DOI: 10.1016/0026-2862(78)90016-X

In order to measure the tissue space accessible to labeled water in the pulmonary parenchyma, a set of multiple-indicator dilution studies was carried out in both exercising dogs and exercising human subjects. Blood labeled with tracer red cells, tracer albumin, and tracer water was injected into the blood stream entering the right heart, and rapid sequential samples were obtained from the arterial side of the circulation. Dilution curves were obtained by analyzing these samples for the appropriate tracers. Conservation considerations indicate that extravascular lung water should be calculated from these data as the product of the water flow and a transit time difference, the difference between the transit time of labeled water and the transit time which the labeled water would have had if it had not left the circulation. The last parameter is calculated from the labeled red cell and albumin outflow pattern, and the water contents of the red cells and plasma. The extravascular lung water calculated in this manner is found to increase with low-level exercise, and then to change no further at higher levels of exercise. The asymptotic maximum corresponds to the water space in the parenchymal tissue of the lungs. It is smaller than the total water space in the lungs, which includes the airway and hilar tissue, supplied by the bronchial artery. The initial increase in the measured water space, occurring with the transition from rest to low-level exercise, is thought to reflect pulmonary capillary recruitment. Simultaneous exploration of the single-breath pulmonary diffusing capacity for carbon monoxide shows a continuous increase with increase in flow, even over the upper range, where the water space no longer changes. The dissociation between the two measurements over the upper range raises a new question: Is part of the increase in the diffusing capacity blood flow dependent, rather than dependent on the recruitment of additional surface for exchange?