Pathophysiological mechanism of long-term noninvasive ventilation in stable hypercapnic patients with COPD using functional respiratory imaging.
INTRODUCTION
Patients with severe COPD often develop chronic hypercapnic respiratory failure. Their prognosis worsens and they are more likely to develop exacerbations. This has major influence on the health-related quality of life. Currently, there is no information about the success of long-term noninvasive ventilation (NIV) among patients who receive NIV in acute settings. Also, little is known about the pathophysiological mechanism of NIV.


METHODS
Ten Global Initiative for Obstructive Lung Disease stage III and IV COPD patients with respiratory failure who were hospitalized following acute exacerbation were treated with NIV using a Synchrony BiPAP device for 6 months. Arterial blood gases and lung function parameters were measured. Low-dose computed tomography of the thorax was performed and used for segmentation. Further analyses provided lobe volume, airway volume, and airway resistance, giving an overall functional description of the separate airways and lobes. Ventilation perfusion (VQ) was calculated. Patient-reported outcomes were evaluated.


RESULTS
PaCO2 significantly improved from 50.03 mmHg at baseline to 44.75 mmHg after 1 month and 43.37 mmHg after 6 months (P=0.006). Subjects showed improvement in the 6-minute walk tests (6MWTs) by an average of 51 m (from 332 m at baseline to 359 m at 1 month and 383 m at 6 months). Patients demonstrated improvement in self-reported anxiety (P=0.018). The improvement in image-based VQ was positively associated with the 6MWT and the anxiety domain of the Severe Respiratory Insufficiency Questionnaire.


CONCLUSION
Though previous studies of long-term NIV have shown conflicting results, this study demonstrates that patients can benefit from long-term NIV treatment, resulting in improved VQ, gas exchange, and exercise tolerance.
['Hajian|Bita|B|', 'De Backer|Jan|J|', 'Sneyers|Claire|C|', 'Ferreira|Francisca|F|', 'Barboza|Katherine C|KC|', 'Leemans|Glenn|G|', 'Vos|Wim|W|', 'De Backer|Wilfried|W|']
D018450:Disease Progression D017079:Exercise Tolerance D006801:Humans D006935:Hypercapnia D008168:Lung D063087:Noninvasive Ventilation D000071066:Patient Reported Outcome Measures D055420:Perfusion Imaging D011237:Predictive Value of Tests D029424:Pulmonary Disease, Chronic Obstructive D011659:Pulmonary Gas Exchange D020127:Recovery of Function D012131:Respiratory Insufficiency D012720:Severity of Illness Index D013997:Time Factors D014057:Tomography, X-Ray Computed D016896:Treatment Outcome
noninvasive ventilation COPD functional respiratory imaging exacerbations BiPAP ventilation perfusion hypercapnia