RATIONALE: Patients with chronic obstructive pulmonary disease (COPD) primarily describe their exertional dyspnea using descriptors alluding to increased effort or work of breathing and unsatisfied inspiration or inspiratory difficulty. OBJECTIVES: The purpose of this study was to examine the impact of changes in dynamic respiratory mechanics during incremental (INCR) and high-intensity constant work-rate (CWR) cycle exercise on the evolution of dyspnea intensity and its major qualitative dimensions in patients with moderate-to-severe COPD. METHODS:Sixteen subjects with COPD performed symptom-limited INCR and CWR cycle exercise tests. Measurements included dyspnea intensity and qualitative descriptors, breathing pattern, operating lung volumes, and esophageal pressure (Pes). MEASUREMENTS AND MAIN RESULTS: During both exercise tests, there was an inflection in the relation between tidal volume (Vt) and ventilation. This inflection occurred significantly earlier in time during CWR versus INCR exercise but at a similar ventilation, Vt, and tidal Pes swing. Beyond this inflection, there was no further change in Vt despite a continued increase in ventilation and tidal Pes. During both tests, "work and effort" was the dominant dyspnea descriptor selected up to the inflection point, whereas after this point dyspnea intensity and the selection frequency of "unsatisfied inspiration" rose sharply. CONCLUSIONS: Regardless of the exercise test protocol, the inflection (or plateau) in the Vt response marked the point where dyspnea intensity rose abruptly and there was a transition in the dominant qualitative descriptor choice from "work and effort" to "unsatisfied inspiration." Intensity and quality of dyspnea evolve separately and are strongly influenced by mechanical constraints on Vt expansion during exercise in COPD.
RCT Entities:
RATIONALE: Patients with chronic obstructive pulmonary disease (COPD) primarily describe their exertional dyspnea using descriptors alluding to increased effort or work of breathing and unsatisfied inspiration or inspiratory difficulty. OBJECTIVES: The purpose of this study was to examine the impact of changes in dynamic respiratory mechanics during incremental (INCR) and high-intensity constant work-rate (CWR) cycle exercise on the evolution of dyspnea intensity and its major qualitative dimensions in patients with moderate-to-severe COPD. METHODS: Sixteen subjects with COPD performed symptom-limited INCR and CWR cycle exercise tests. Measurements included dyspnea intensity and qualitative descriptors, breathing pattern, operating lung volumes, and esophageal pressure (Pes). MEASUREMENTS AND MAIN RESULTS: During both exercise tests, there was an inflection in the relation between tidal volume (Vt) and ventilation. This inflection occurred significantly earlier in time during CWR versus INCR exercise but at a similar ventilation, Vt, and tidal Pes swing. Beyond this inflection, there was no further change in Vt despite a continued increase in ventilation and tidal Pes. During both tests, "work and effort" was the dominant dyspnea descriptor selected up to the inflection point, whereas after this point dyspnea intensity and the selection frequency of "unsatisfied inspiration" rose sharply. CONCLUSIONS: Regardless of the exercise test protocol, the inflection (or plateau) in the Vt response marked the point where dyspnea intensity rose abruptly and there was a transition in the dominant qualitative descriptor choice from "work and effort" to "unsatisfied inspiration." Intensity and quality of dyspnea evolve separately and are strongly influenced by mechanical constraints on Vt expansion during exercise in COPD.
Authors: Bradley S Quon; Sabrina S Wilkie; Yannick Molgat-Seon; Michele R Schaeffer; Andrew H Ramsook; Pearce G Wilcox; Jordan A Guenette Journal: J Appl Physiol (1985) Date: 2015-10-01
Authors: Benjamin M Smith; Steven M Kawut; David A Bluemke; Robert C Basner; Antoinette S Gomes; Eric Hoffman; Ravi Kalhan; João A C Lima; Chia-Ying Liu; Erin D Michos; Martin R Prince; LeRoy Rabbani; Daniel Rabinowitz; Daichi Shimbo; Steven Shea; R Graham Barr Journal: Circulation Date: 2013-03-14 Impact factor: 29.690
Authors: Julia M Cory; Michele R Schaeffer; Sabrina S Wilkie; Andrew H Ramsook; Joseph H Puyat; Brandon Arbour; Robbi Basran; Michael Lam; Christian Les; Benjamin MacDonald; Dennis Jensen; Jordan A Guenette Journal: J Appl Physiol (1985) Date: 2015-09-03
Authors: Asha Hareendran; Nancy K Leidy; Brigitta U Monz; Randall Winnette; Karin Becker; Donald A Mahler Journal: Int J Chron Obstruct Pulmon Dis Date: 2012-05-28