Which of the following would be the most reasonable step in the assessment of the patient of emphysema due to alpha 1 ATD.

To establish baseline information in persons who have emphysema, spirometry should be performed, and for persons with significant complaints or physical findings, arterial blood gases also should be checked. Although cigarette smoking accounts for the vast majority of cases of emphysema, a small percentage of persons who develop this illness have had no exposure to tobacco products. A subset of this nonsmoking, emphysematous population is deficient in α1-antitrvpsin. which is a protease inhibitorthat normally is found in the serum. It is currently believed that release of proteolytic enzymes from inflammatory cells accounts for the lung destruction that typifies emphysema, and (Xl-antitrypsin deficiency, a familial disorder, the genotype of which is acid starch gel and immunoelectrophoresis, permits this destruction to occur unimpeded. Exercise testing is not necessary as an initial screening test for emphysema but should be considered before oxygen therapy is prescribed. A male who has emphysematous respiratory failure, gives no history of respiratory infections, and has children would not have cystic fibrosis (affected men are sterile); therefore, a sweat chloride test would not be a useful procedure. High-resolution CT scan would unlikely add any significant alteration to the differential diagnosis, and both an exercise stress test as well as an echocardiogram are not necessary in the evaluation of this patient.