Timing of transplantation referral Timing of referral for transplantation should be determined by factors such as Degree of obstructive defect: Forced expiratory volume in 1 second (FEV1) < 25 to 30% predicted in patients with COPD, alpha-1 antitrypsin deficiency, or cystic fibrosis PaO2 < 55 mm Hg PaCO2 > 50 mm Hg Right atrial pressure > 10 mm Hg and peak systolic pressure > 50 mm Hg for patients with primary pulmonary hypertension Progression rate of clinical, radiographic, or physiologic disease Procedure The donor is anticoagulated, and a cold crystalloid preservation solution containing prostaglandins is flushed through the pulmonary arteries into the lungs.