Expiratory flow rates were normal (FEV1, 1.3 L[
108%]; FVC, 2.0 L [107%]). Lung volumes via dilution were all
slightly elevated. Dlco was severely reduced, at 4 mL/mm
Hg/min (23%). The expiratory flow-volume loop is shown in Figure 1
. Chest radiographic findings were normal. Radionucleotide
ventilation-perfusion lung scan findings were low probability for
thromboembolism, and ultrasound revealed patent leg veins. Resting room
air blood gases showed the following findings:
Pao2, 52 mm Hg;
Paco2, 37 mm Hg; arterial oxygen
saturation, 88%, which decreased to 78% following a brief walk.
Hemoglobin level was 16.6 g/dL. High-resolution CT scan (HRCT) showed
diffuse centrilobular emphysema, with no bullae or interstitial disease
). Home oxygen therapy was continued, and treatment with inhaled
bronchodilation was initiated in attempt to improve her dyspnea. She
remained in clinically stable condition and was oxygen dependent.