RESULTS: Eight of nine patients were male; age ranged from 47-68yr. Seven patients had a smoking history, and seven had a BMI<30kg/m2. Airflow obstruction (FEV1/FVC < 0.7) was present in eight of nine patients (range 0.28-0.81). All patients had an elevated FRC (range 113-184% predicted) and TLC was elevated in five patients (range 90-148% predicted). DLCO was reduced in seven of eight patients with valid data (range 28% to 117% predicted). Three patients were classified as emphysema predominant, three chronic bronchitis predominant, and three with a mixed phenotype. Lung recoil pressure was reduced in all patients with emphysema predominant (range 9-20cmH2O), in two of three patients with a mixed phenotype (range 9-27cmH2O), and in one of three patients with chronic bronchitis predominant (range 14-25cmH2O). Oscillometry testing revealed normal to near normal resistance and reactance in the emphysema predominant phenotype (R5, 3.12-5.94cmH2O/l/s; R5-20, 0.39-1.24cmH2O/l/s; X5, -0.11- -1.11cmH2O/l/s). Resistance and reactance were elevated in chronic bronchitis predominant and mixed phenotypes (R5, 6.59-11.47cmH2O/l/s; R5-20, 2.16-3.80cmH2O/l/s; X5, -2.50- -6.59cmH2O/l/s).