The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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Randomized Controlled Trial Clinical Trial
Effects of proportional assist ventilation on exercise tolerance in COPD patients with chronic hypercapnia.
This study investigates the impact of proportional assist ventilation (PAV), a new mode of partial ventilatory support, on exercise tolerance and breathlessness in severe hypercapnic chronic obstructive pulmonary disease (COPD) patients. We also examined the effects of continuous positive airway pressure (CPAP) and pressure support ventilation (PSV). On two consecutive days, 15 stable hypercapnic COPD patients underwent four endurance tests on a cycle ergometer at 80% of their maximal workrate, receiving, via a nasal mask in random order, either: 1) sham ventilation (CPAP: 1 cmH2O); 2) CPAP (6 cmH2O); 3) PSV (inspiratory pressure support: 12-16 cmH2O; expiratory positive airway pressure (EPAP): 1 cmH2O); or 4) PAV (8.6+/-3.6 cmH2O x L(-1) and 3+/-1.3 cmH2O x L(-1)x s(-1) of volume and flow assistance, respectively plus EPAP: 1 cmH2O). ⋯ In comparison to sham ventilation, PAV, PSV and CPAP were able to increase the endurance time (from 7.2+/-4.4 to 12+/-5.6, 10+/-5.2 and 9.6+/-4.6 min, respectively) and to reduce dyspnoea and oxygen flow to the nasal mask. However, the greatest improvement was observed with PAV. We conclude that PAV delivered by nasal mask can im-prove exercise tolerance and dyspnoea in stable hypercapnic COPD patients and hence this mode of ventilatory support may be useful in respiratory rehabilitation programmes.