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Clinical Investigations: COPD |

Dyspnea, Ventilatory Pattern, and Changes in Dynamic Hyperinflation Related to the Intensity of Constant Work Rate Exercise in COPD*

Luis Puente-Maestu, MD, PhD; Julia García de Pedro, MD, PhD; Yolanda Martínez-Abad, MD; José Maria Ruíz de Oña, MD; Daniel Llorente, MD; José Manuel Cubillo, MD
Author and Funding Information

*From the Hospital General Universitario Gregorio Marañón (Drs. Puente-Maestu, Martínez-Abad, and Cubillo), Servicio de Neumología, Madrid, Spain; Hospital Virgen de la Torre (Drs. García de Pedro and Ruíz de Oña), Madrid, Spain; and Hospital La Mancha Centro (Dr. Llorente), Aleázar de San Juan Ciudad Real, Spain.

Correspondence to: Luis Puente-Maestu, MD, PhD, Hospital General Universitario Gregorio Marañón, Servicio de Neumología, c/o Doctor Ezquerdo 46, 28007 Madrid, Spain; e-mail: lpuente@separ.es



Chest. 2005;128(2):651-656. doi:10.1378/chest.128.2.651
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Study objective: We undertook the present study to investigate the perception of dyspnea (with respect to changes in end-inspiratory and end-expiratory lung volumes), during four different levels of high-intensity constant work rate exercise (CWRE) in patients with severe COPD.

Design: Crossover descriptive study with consecutively recruited subjects.

Setting: Tertiary university hospital.

Patients: Twenty-seven subjects with severe COPD (mean [± SD] age, 65 ± 5 years of age; mean FEV1, 43 ± 8% predicted; and mean inspiratory capacity [IC]; 74 ± 14% predicted).

Measurements and results: Subjects randomly performed four high-intensity CWRE tests (conducted at 65%, 75%, 85%, and 95% of their symptom-limited peak work rate). Dyspnea, leg fatigue, and IC were determined every 2 min during exercise with breath-by-breath gas exchange and ventilatory measurements. There was a good correlation between the resting IC percent predicted and the oxygen uptake (V̇o2) peak (r = 0.64 to 0.69 between the IC percent predicted and V̇o2 peak at the four work rates). There were significant differences (p < 0.01) in mean respiratory rate (33 ± 6, 35 ± 6, 37 ± 6, and 38 ± 6 min), peak dyspnea score (5.9 ± 1.3, 6.3 ± 1.4, 6.8 ± 1.2, and 6.9 ± 1.6), minute ventilation (45.0 ± 8.7, 43.8 ± 7.7, 43.1 ± 8.7, and 42.8 ± 8.0 L/min), leg fatigue (4.8 ± 1.3, 5.1 ± 1.3, 5.7 ± 1.4, and 5.8 ± 1.4), and end-tidal carbon dioxide partial pressure (4.41 ± 0.36, 4.53 ± 0.33, 4.66 ± 0.31, and 4.76 ± 0.24 kPa), respectively, for tests conducted at 65%, 75%, 85%, and 95% of their symptom-limited peak work rate, and in mean end-expiratory lung volume ([EELV] 4.55 ± 0.44, 4.69 ± 0.43, and 4.79 ± 0.43 L), respectively, for tests conducted at 65%, 75%, and 85% of their symptom-limited peak work rate. In multivariable analysis, the factors that were independently correlated with dyspnea (p < 0.05) were EELV, peak inspiratory flow, and leg fatigue/discomfort.

Conclusion: In COPD subjects with flow limitation at rest, the perception of dyspnea increased nonlinearly with the magnitude of high-intensity CWRE in association with a faster respiratory pattern and an increase in EELV. At the highest work rates, it appeared that a reduction in tidal volume and ventilation peak may have limited the tolerance to exercise.

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