Decompensated type 2 respiratory failure during acute exacerbation of chronic obstructive pulmonary disease (COPD) is treated with non-invasive ventilation (NIV) and nebulized bronchodilators. Nebulization during NIV can be applied by two methods: in-line nebulization through NIV mask and off-NIV nebulization during which NIV mask is taken off for a short time and reapplied when nebulization is finished.
This study is a prospective randomized controlled trial to compare in-line nebulization through NIV versus off- NIV nebulization. After starting NIV in eligible COPD patients with type 2 respiratory failure, the baseline end-expiratory lung impedance (EELI) will be measured. Patient is randomized to receive either in-line or off-NIV nebulization. EELI will be measured again following completion of the nebulization, 15min after NIV is restarted (off-NIV group) or continued (in-line group). Ultrasound measurement of the thickness of the diaphragm will be recorded at baseline, 15min after NIV is restarted (off-NIV group) or continued (in-line group) and 48 hours after stopping the NIV. The main outcome measure, difference in mean end expiratory lung volume at 15min after NIV is restarted (off-NIV group) or continued (in-line group) between the two nebulization methods will be compared using independent sample T test. Thickness of the diaphragm and changes in the arterial blood gases (in terms of pH and carbon-di-oxide) will be compared between in-line nebulization and off-NIV nebulization.
