Use of an hypoxic lung as a deoxygenator to provide extended assessment of pulmonary function in rats. Decampos, Kleber N., Shaf H. Keshavjee, Lorraine Tremblay, Toshiyuki Yamashiro, Arthur S. Slutsky. Divisions of Thoracic Surgery and Respirology, Departments of Surgery and Medicine, The Toronto Hospital, and The Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
APStracts 3:0057A, 1996.
Isolated perfused lung systems are commonly used to assess lung function in experimental studies. Assessment of hemodynamics and gas exchange function in these systems is limited by the availability of venous blood. This study describes and validates a rat lung perfusion circuit in which a double-lung block ventilated with an hypoxic gas mixture (FIO2 0.04, FICO2 0.08; deoxy block) is used to provide blood, with blood gases that are similar to mixed venous values, to perfuse a study lung (FIO2 0.21; left lung only). This allows extended assessment of hemodynamics and gas exchange. Fifty adult male Wistar rats (300-400 g) were used as double-lung donors. Twenty five perfusions (of both deoxy and study lungs) were performed in 4 protocols (groups 1 to 5; n=5). In protocol 1 (group 1), we tested whether exposure to room air affects the gas composition of the blood in the system. We found that the gas composition of the venous reservoir blood was identical to that of the blood entering the study block. In protocol 2, the effect of perfusion time and perfusion flow rate on the stability of the system was assessed. Lungs were perfused at 4 and 12 ml/min (groups 2 & 3, respectively) and the procedure was discontinued if edema, or a marked decline in hemodynamics, or gas exchange function was observed. Pulmonary function was excellent and remained stable for 3h (at 12 ml/min), and 5h (at 4 ml/min). In protocol 3, we examined whether hypoxic ventilation in the deoxy lungs affects the stability of the system. Despite the low FIO2 used in the deoxy lungs, the Ppa-Q relationships in the study and deoxy lungs were similar. Finally, in protocol 4, perfusion of a damaged study lung did not impair the function of the system. We conclude that this model permits reliable assessment of pulmonary function in rats under controlled ventilation and perfusion conditions. The use of a deoxygenator double-lung block simplifies the perfusion apparatus and eliminates the main cause of instability of other systems which use an anaesthetized host animal to provide venous blood. 

Received 10 April 1995; accepted in final form 30 November 1995.
APS Manuscript Number A386-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 January 96