Donors must be < 65 and never-smokers and have no active lung disorder as evidenced by Oxygenation: PaO2/FIO2 (fractional inspired O2) > 250 to 300, with PaO2 in mm Hg and FIO2 in decimal fraction (eg, 0.5) Lung compliance: Peak inspiratory pressure < 30 cm H2O at tidal volume (V T) 15 mL / kg and positive end-expiratory pressure = 5 cm H2O Gross appearance: Using bronchoscopy Donor and recipients must be size-matched anatomically (by chest x-ray), physiologically (by total lung capacity), or both.