Efficacy of Positive vs Negative Pressure Ventilation in Unloading the Respiratory Muscles (1)Assisted ventilation (AV) can improve alveolar venti-L lation in patients with neuromuscular or thoracic cage abnormalities. Because respiratory muscle fatigue may aggravate the already impaired function of the respiratory muscles in patients with chronic obstructive pulmonary disease (COPD), ventilatory muscle rest (VMR) by means of assisted ventilation has been advocated in these patients.” asthma inhalers
Most studies have used negative pressure ventilation (NPV) as a means of applying assisted ventilation in patients with COPD. However, not all investigators have shown beneficial results. Ventilatory support has been applied at different intervals ranging from daily to weekly, and from a few days to a few months in duration. In the most extreme case, Gutierrez and coworkers were able to demonstrate increases in tidal volume, maximal inspiratory mouth pressures, and improved gas exchange after four months of weekly NPV. Zibrak and coworkers reported problems with patient acceptance and comfort during NPV and failed to demonstrate any clinical benefit. Celli and colleagues showed that patients randomized to receive rehabilitation alone and rehabilitation plus NPV improved their exercise capacity symptoms to a similar degree.