Background: Heart failure is one of the most leading cause of death worldwide, but the mechanical characteristics of the pulmonary system in these patients have not been studied enough. The aim of this study was to measure mechanical pulmonary changes in patients with congestive heart failure (CHF) by using impulse oscillometry (IOS), which can obtain data by simpler means and independently from respiratory muscle strength. Materials and methods: We assessed 24 CHF patients and 24 controls by spirometry and IOS using the Jaeger IOS system. IOS measures central and peripheral airway resistances (R20, R5) and central and peripheral reactances (X20, X5) using sound waves with different frequencies, which superimposed on the patients respiratory tidal volume and then records reflects. P value < 0.05 was taken to be significant. Results: The mean age of patients and controls was 61 10 and 57 7 years, respectively. The mean ejection fraction (EF) was 37 17% for patients and 55 7% for controls. Patients had a lower X5 (0.20 0.13 vs 0.13 0.07; P < 0.05), forced expiratory volume in 1 second (FEV1; 2.26 0.68 vs 3.09 0.82: P < 0.01 L/min), and forced vital capacity (FVC; 2.55 0.86 vs 3.32
0.87; P < 0.05) compared to the controls. They also had elevated R5: 0.37 0.21 vs 0.27 0.09; P < 0.06). X5 was correlated with spirometric abnormalities (P < 0.05) and was lower in patients than in controls. Conclusion: X5 was lower and R5 was higher in patients than in controls. CHF patients can be assessed by IOS more comfortable than by spirometry. IOS can reliably measure peripheral airway resistance in this group of patients.