Does expiratory flow limitation predict chronic dyspnoea in adults with cystic fibrosis?

¹ Dept of Physiotherapy; and School of Physiotherapy, University of Melbourne
² School of Physiotherapy, University of Melbourne
³ Dept of Allergy, Immunology and Respiratory Medicine, Alfred Hospital; and Dept of Medicine, Monash University, Melbourne, Australia

	Abstract

Tidal expiratory flow limitation (EFL) may promote dynamic hyperinflation and contribute to chronic dyspnoea. The purpose of this study was to assess the contribution of EFL to chronic dyspnoea in adults with cystic fibrosis (CF).

The presence of EFL was determined in 102 adults with stable CF (FEV₁ 17.3-91.5% predicted) and 20 age-matched control subjects using the Negative Expiratory Pressure (NEP) technique. Measurements of inspiratory capacity (IC) and spirometry were performed, and chronic dyspnoea was evaluated using the modified Medical Research Council (MRC) scale.

EFL was present in 34 subjects (33%), with 18 subjects flow limited in sitting and 16 subjects flow limited only in supine. Flow limitation in sitting was associated with older age and lower FEV₁ compared to flow-limited supine and non-flow limited subjects. A significant reduction in IC accompanied EFL in both sitting and supine. Flow limitation in sitting was associated with significantly higher levels of chronic dyspnoea. Ordinal regression analysis indicated that EFL was the best predictor of chronic dyspnoea in a model that included FEV₁%predicted.

Expiratory flow limitation in CF is associated with reduced FEV₁, older age and dynamic hyperinflation. Expiratory flow limitation significantly contributes to chronic dyspnoea in CF.

This article has been cited by other articles:

				R. Walker, J. Paratz, and A. E. Holland Reproducibility of the Negative Expiratory Pressure Technique in COPD Chest, August 1, 2007; 132(2): 471 - 476. [Abstract] [Full Text] [PDF]