Oscillometry to Assess Respiratory Function in Adult Cystic Fibrosis

Abstract

Oscillometry to Assess Respiratory Function in Adult Cystic FibrosisBackground and Rationale: Cystic fibrosis (CF) is a life-limiting multi-system disorder in which respiratory dysfunction predominates. Although spirometry is the most commonly used test of pulmonary function, it has recognized limitations. Oscillometry is an alternative test of respiratory function which provides complementary information. Oscillometry also offers a number of practical and physiological advantages and is increasingly used in both clinical research and patient care. Surprisingly, little data exists using oscillometry to evaluate lung function in adults with CF.Accordingly, the aim of this study was to compare spirometry and oscillometry in a large adult CF cohort. Methods: Spirometry and oscillometry (tremoFlo® C-100, Thorasys Thoracic Medical Systems Inc., Montreal, Canada) were performed according to published guidelines during a routine visit to the Montreal Chest Institute Adult CF Clinic, McGill University Health Centre in 92 adults with established CF in stable state (mean age = 33.0 ± SE 1.3 yrs, 51 men). Oscillometry parameters included respiratory resistance at 5 Hz (R5), the difference in respiratory resistance at 5 and 20 Hz (R5-20), respiratory reactance at 5 Hz (X5), respiratory reactance area (AX), and resonant frequency (Fres).Results: Respiratory function was significantly reduced for the group (forced expiratory volume in one second, FEV1 = 2.27 ± SE 0.1 L; Z score = -3.38 ± SE 0.23). There was generally a good to strong correlation between spirometry and oscillometry parameters, particularly between FEV1 and both X5 and AX, and all relationships were highly significant (P < 0.001). Results were generally similar when expressed as absolute values or Z scores. Logistic regression and marginal