Inspiratory Constraints and Ventilatory Inefficiency Are Superior to Breathing Reserve in the Assessment of Exertional Dyspnea in COPD.

Inspiratory Constraints and Ventilatory Inefficiency Are Superior to Breathing Reserve in the Assessment of Exertional Dyspnea in COPD. COPD. 2019 Jul 05;:1-8 Authors: Neder JA, Berton DC, Marillier M, Bernard AC, O'Donnell DE, Canadian Respiratory Research Network Abstract Combining measurements of impaired lung mechanics (inspiratory constraints) with an index of increased respiratory stimuli to metabolic demand (poor ventilatory efficiency) might enhance the ability of cardiopulmonary exercise testing (CPET) in exposing a mechanistic role for ventilation on exertional dyspnea in COPD. In addition to the standard approach to suggest ventilatory limitation to exercise - a low breathing reserve (1-(peak ventilation (V̇E)/maximal voluntary ventilation × 100 < 20%) - we assessed the presence of critical inspiratory constraints (end-inspiratory lung volume (EILV)/total lung capacity (TLC) ≥ 0.9) and ventilatory inefficiency (V̇E/CO2 output (V̇CO2) nadir > 34) in 288 patients with mild to very severe COPD (FEV1 ranging from 18 to 121% predicted). We found that ∼50% of the patients with preserved breathing reserve developed critical inspiratory constraints. A low breathing reserve was weakly related to a lower peak O2 uptake (V̇O2) and/or a higher dyspnea burden; for instance, patients with low breathing reserve but without critical inspiratory constraints had similar dyspnea and peak V̇O2 than those with preserved bre...
Source: COPD: Journal of Chronic Obstructive Pulmonary Disease - Category: Respiratory Medicine Tags: COPD Source Type: research