Physiologic Effects of Noninvasive Ventilation in Patients With Chronic Obstructive Pulmonary Diseas

• Published in: Archivos de bronconeumología (English ed.) 2007, Vol.43 (3), p.150-155
• Main Authors: Neme, Jorge Y., Gutiérrez, Amalia M., Santos, M. Cristina, Berón, Marta, Ekroth, Cristina, Arcos, José P., Píriz, Héctor, Hurtado, F Javier
• Format: Article
• Language: English
• Subjects: Chronic respiratory failure; Continuous positive airway pressure; COPD; EPOC; Insuficiencia respiratoria crónica; Noninvasive ventilation; Presión de soporte; Presión positiva continua de la vía aérea; Pressure support ventilation; Pulmonary disease, chronic obstructive; Trabajo respiratorio; Ventilación no invasiva; Work of breathing
• ISSN: 1579-2129; 1579-2129
• DOI: 10.1016/S1579-2129(07)60039-1

Noninvasive mechanical ventilation has been of use in the treatment of some forms of chronic and acute respiratory failure. However, the benefits of its use in patients in the stable phase of severe chronic obstructive pulmonary disease (COPD) remain unclear. A combination of continuous positive airway pressure (CPAP) and pressure support ventilation (PSV) may improve respiratory mechanics and alveolar ventilation, and reduce inspiratory muscle effort. In this study, we analyzed the physiologic effects of differing levels of CPAP and CPAP plus PSV in patients with stable severe COPD. Work of breathing, breathing pattern, oxygen saturation measured by pulse oximetry, PaO 2, and PaCO 2 were analyzed in a group of 18 patients under the following conditions: a) baseline; b) CPAP, 3 cm H 20; c) CPAP, 6 cm H 20; d) CPAP 3 cm H 20 plus PSV 8 cm H 20; and e) CPAP 3 cm H 20 plus PSV 12 cm H 20. CPAP at pressures of 3 and 6 cm H 20 was associated with an increase in tidal volume (V T) from a mean (SD) baseline value of 0.52 (0.04) L to 0.62 (0.04) and 0.61 (0.03) L, respectively. Minute ventilation increased from 8.6 (0.5) L/min to 10.8 (0.6) and 10.9 (0.5) L/min, respectively. Mean inspiratory flow (V T/Ti) increased from 0.35 (0.02) L/s to 0.44 (0.02) and 0.41 (0.02) L/s, respectively, and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn) was reduced from 1.63 (0.7) cm H 20 to 1.1 (0.06) and 0.37 (0.4) cm H 20, respectively. CPAP did not reduce the work of breathing. Association of CPAP at 3 cm H 20 with PSV of 8 or 12 cm H 20 increased V T to 0.72 (0.07) and 0.87 (0.08) L, respectively, while minute ventilation increased to 12.9 (0.8) and 14.9 (1.1) L/s, respectively. Mean inspiratory flow also increased to 0.50 (0.03) and 0.57 (0.03) L/s, respectively. Work of breathing was reduced from 0.90 (0.01) J/L to 0.48 (0.06) and 0.30 (0.06) J/L, respectively, while PEEPi,dyn increased to 1.30 (0.02) and 2.42 (0.08) cm H 20, respectively. With combined CPAP of 3 cm H 20 and PSV of 12 cm H 20, PaCO 2 was reduced from a baseline value of 41.2 (1.5) mm Hg to 38.7 (1.9) mm Hg. All of the changes were statistically significant (P