Feedback-controlled negative pressure ventilation in patients with stable severe hypercapnic chronic obstructive pulmonary disease.

Background: In recent studies, the efficacy of intermittent rest of the inspiratory muscles as an option of treating patients with severe chronic obstructive pulmonary disease (COPD) has become questionable.

Objective: The aim of our study was to analyze the effects of feedback-controlled intermittent negative pressure ventilation (INPV) on stable, but severely hypercapnic COPD patients.

Methods: 21 clinically stable, hypercapnic patients with severe COPD underwent INPV with chest shells for 3 weeks, 6 h a day. The INPV sessions were optimized by a visual biofeedback system, which enabled control over the decrease in diaphragmatic activity. Respiratory muscle (RM) function parameters, lung function parameters, blood gases and exercise capacity were analyzed.

Results: In the end, 19 patients concluded INPV treatment. They had PaO(2) of 56.5 +/- 11.8 mm Hg, PaCO(2) of 50.2+/-2.7 mm Hg (mean +/- SD) and FEV(1) of 27.8 +/- 4.3% predicted before treatment. There was no statistically significant change in lung function parameters, RM function parameters, physical performance and level of dyspnea after 3 weeks of INPV.

Conclusion: We conclude that intermittent RM rest induced by INPV can relax inspiratory muscles in most patients with stable severe COPD, but fails to improve RM function and exercise capacity.