Four-week negative pressure ventilation improves respiratory function in severe hypercapnic COPD patients

Studies on respiratoiy muscle resting by negative pressure ventilation (NPV) in patients with stable COPD bave given conflicting results. Probable explanations lie in criteria of patients’ selection, method of NPV application, and lack of supervision of respiratoiy muscle rest Thirteen hypercapnic patients with COPD were, therefore, randomly assigned to either a NPV group or a control group. The NPV was applied by an airtight jacket (pneumosuit), 5 h a day, 5 consecutive days a week for 4 weeks. Both NPV group and control group performed in-hospital pulmonary rehabilitation program for a 4-week period. Arterial blood gases, spirometry, maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP), breathing pattern, and electromyogram (EMC) of the diaphragm and parasternal intercostal muscles were measured on the preintervention day, and at the end of the second and fourth weeks of treatment (days 13 and 27, respectively). The short-term effect of NPV on EMC suppression was also checked throughout the ventilatolry sessions in three different days (1, 12, and 26, respectively). A 6-min walking test (WT) and level of dyspnea by a modified Borg scale were evaluated on the preintervention and tibe last days. Negative pressure ventilation resulted in a significant reduction in EMG activity of both diaphragm and parasternal muscles, associated with significant increase in MIP, tidal volume, and ventilation, and increase in PaO 2 and decrease in PaCO 2 . A significant relationship between change in MIP and change in PaCO 2 was observed (r = 0.72, p