Influence of intraalveolar oxygen concentration on lung preservation in a rabbit model.

We previously reported the use of an inexpensive screening model for lung preservation involving ventilation and perfusion of excised rabbit lungs after their preservation. We now have extended this model by perfusing the preserved lung in cross circulation with an anesthetized rabbit to permit stable reperfusion of the preserved lungs for 60 minutes. With this model we compared the results of lung preservation with the lungs inflated with nitrogen, room air, or 100% oxygen during 24 hours of hypothermic storage. Four groups of animals were studied: group 1, excision and immediate evaluation; group 2, inflation with room air and storage for 24 hours at 10 degrees C; group 3, same as group 2, with 100% oxygen for inflation during storage; group 4, same as group 2, with 100% nitrogen for inflation during storage. Assessment of the ex vivo perfused lung consisted of (1) blood gas analysis of inflow and outflow blood at 10-minute intervals; (2) continuous pulmonary artery and airway pressure monitoring; (3) measurement of pulmonary venous oxygen tension after 1 hour of reperfusion, with inflow oxygen tension adjusted to 15 mm Hg; (4) wet/dry weight ratio. We conclude that the paracorporeal circuit does not, in itself, cause lung injury over a 1-hour period; lungs preserved with nitrogen inflation rapidly became edematous and failed to function on reperfusion. Preservation with 100% oxygen inflation appears superior to inflation with room air.