Relationships between respiratory and airway resistances and activity-related dyspnea in patients with chronic obstructive pulmonary disease.

Background The aims of the study were: (1) to compare numerical parameters of specific airway resistance (total, sRawtot, effective, sRaweff and at 0.5 L · s−1, sRaw0.5) and indices obtained from the forced oscillation technique (FOT: resistance extrapolated at 0 Hz [Rrs0 Hz], mean resistance [Rrsmean], and resistance/frequency slope [Rrsslope]) and (2) to assess their relationships with dyspnea in chronic obstructive pulmonary disease (COPD).