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

• Published in: International journal of chronic obstructive pulmonary disease Vol. 7; no. default; pp. 165 - 171
• Main Authors: Mahut, Bruno, Caumont-Prim, Aurore, Plantier, Laurent, Gillet-Juvin, Karine, Callens, Etienne, Sanchez, Olivier, Chevalier-Bidaud, Brigitte, Bokov, Plamen, Delclaux, Christophe
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01.01.2012; Dove Medical Press
• Subjects: Aged; Airway Resistance; Care and treatment; Complications and side effects; Cross-Sectional Studies; Diagnosis; Dyspnea - diagnosis; Dyspnea - etiology; Dyspnea - physiopathology; Female; Forced Expiratory Volume; Humans; Lung - physiopathology; Lung diseases, Obstructive; Lung Volume Measurements; Male; Middle Aged; Original Research; Oscillometry; Paris; Plethysmography, Whole Body; Predictive Value of Tests; Principal Component Analysis; Pulmonary Disease, Chronic Obstructive - complications; Pulmonary Disease, Chronic Obstructive - diagnosis; Pulmonary Disease, Chronic Obstructive - physiopathology; Respiration; Risk factors; Severity of Illness Index; Shortness of breath; Spirometry; Vital Capacity; Paris; France; body plethysmography; forced oscillation technique; principal component analysis
• ISSN: 1178-2005; 1176-9106; 1178-2005
• DOI: 10.2147/COPD.S29745

The aims of the study were: (1) to compare numerical parameters of specific airway resistance (total, sRaw(tot), effective, sRaw(eff) and at 0.5 L · s(-1), sRaw(0.5)) and indices obtained from the forced oscillation technique (FOT: resistance extrapolated at 0 Hz [Rrs(0 Hz)], mean resistance [Rrs(mean)], and resistance/frequency slope [Rrs(slope)]) and (2) to assess their relationships with dyspnea in chronic obstructive pulmonary disease (COPD). A specific statistical approach, principal component analysis that also allows graphic representation of all correlations between functional parameters was used. A total of 108 patients (mean ± SD age: 65 ± 9 years, 31 women; GOLD stages: I, 14; II, 47; III, 39 and IV, 8) underwent spirometry, body plethysmography, FOT, and Medical Research Council (MRC) scale assessments. Principal component analysis determined that the functional parameters were described by three independent dimensions (airway caliber, lung volumes and their combination, specific resistance) and that resistance parameters of the two techniques were not equivalent, obviously. Correlative analyses further showed that Raw(tot) and Raw(eff) (and their specific resistances) can be considered as equivalent and correlated with indices that are considered to explore peripheral airways (residual volume (RV), RV/ total lung capacity (TLC), Rrs(slope)), while Rrs(mean) and Raw(0.5) explored more central airways. Only specific resistances taking into account the specific resistance loop area (sRaw(tot) and sRaw(eff)) and Rrs(slope) were statistically linked to dyspnea. Parameters obtained from both body plethysmography and FOT can explore peripheral airways, and some of these parameters (sRaw(tot), sRaw(eff,) and Rrs(slope)) are linked to activity-related dyspnea in moderate to severe COPD patients.