During exercise non-invasive ventilation in chronic restrictive respiratory failure.

Borel, Jean-Christian; Wuyam, Bernard; Chouri-Pontarollo, Nathalie; Deschaux, Chrystèle; Levy, Patrick; Pépin, Jean-Louis

BACKGROUND Exercise intolerance limits chronic restrictive respiratory failure (CRF) patients from participating in daily activities. The specific modalities that could improve exercise tolerance in these patients remain to be established. OBJECTIVE To investigate exercise endurance and associated physiological responses with non-invasive ventilation (NIV) during exercise in restrictive CRF patients. METHODS Eighteen patients (63+/-11 years, total lung capacity (TLC)=59+/-16% of predicted value) performed maximal exercise in spontaneous breathing conditions (MWLE) and during two constant workload exercise (CWLE) tests at 75% Pmax, with or without NIV in random order. "NIV Responders" were defined by an increase in CWLE duration of more than 50% when using NIV. RESULTS For the whole group, CWLE duration when using NIV increased from 5.6+/-4.6 to 9.6+/-8.1 min. Increase in CWLE duration correlated with reduction in heart rate and oxygen desaturation, and dyspnea relief during exercise. NIV responders (n=9) showed more severe lung restriction (TLC: 2.6+/-0.7 versus 3.5+/-1.1L; forced vital capacity: 1.0+/-0.16 versus 1.46+/-0.38 L). At the end of MWLE, responders had a lower Vt (0.60+/-0.09 versus 0.89+/-0.34 L), a higher dead-space ratio (0.51+/-0.06 versus 0.38+/-0.12) and lower oxygen pulse (4.5+/-1.2 versus 7.4+/-3.9 ml/beat). CONCLUSION In severely restrictive patients, NIV during exercise significantly improved exercise duration and tolerance and increased alveolar ventilation. TRIAL REGISTRATION The enrollment of the patients started before July 1, 2005.