Abstract
BACKGROUND: Non-invasive ventilation (NIV) is a recommended treatment for COPD patients suffering from chronic hypercapnic respiratory failure. Prolonged dyspnea after mask removal in the morning, often referred to as deventilation syndrome, is a common side effect but has been poorly characterized yet. This study aimed to explore the pathomechanism, identify risk factors and possible treatment strategies for the deventilation syndrome. METHODS: A prospective, controlled, non-blinded study was conducted. After a night with established NIV therapy, the patients underwent spirometry, blood gas analyses and 6-min walking tests (6MWT) directly, at 2 and 4 h after mask removal. Dyspnea was measured by the modified Borg scale. Bodyplethysmography and health-related quality of life (HRQoL) questionnaires were used. Patients suffering from deventilation syndrome (defined as dyspnea of at least three points on the Borg scale after mask removal) were treated with non-invasive pursed lip breathing ventilation (PLBV) during the second night of the study. RESULTS: Eleven of 31 patients included (35%) met the given criteria for a deventilation syndrome. They reported significantly more dyspnea on the Borg scale directly after mask removal (mean: 7.2 ± 1.0) compared to measurement after 2 h (4.8 ± 2.6; p = 0.003). Initially, mean inspiratory vital capacity was significantly reduced (VCmax: 46 ± 16%) compared to 2 h later (54 ± 15%; p = 0.002), while no changes in pulse oximetry or blood gas analysis were observed. Patients who suffered from a deventilation syndrome had a significantly higher mean airway resistance (Reff: 320 ± 88.5%) than the patients in the control group (253 ± 147%; p = 0.021). They also scored significantly lower on the Severe Respiratory Insufficiency Questionnaire (SRI; mean: 37.6 ± 10.1 vs 50.6 ± 16.7, p = 0.027). After one night of ventilation in PLBV mode, mean morning dyspnea decreased significantly to 5.6 ± 2.0 compared to 7.2 ± 1.0 after established treatment (p = 0.019) and mean inspiratory vital capacity increased from 44 ± 16.0% to 48 ± 16.3 (p = 0.040). CONCLUSIONS: The deventilation syndrome is a serious side effect of NIV in COPD patients, characterized by increase of dyspnea. It is associated with decrease in vital capacity, exercise tolerance after mask removal and lower HRQoL. Patients with high airway resistance are at greater risk of suffering from morning dyspnea. Ventilation in PLBV mode may prevent or improve the deventilation syndrome. TRIAL REGISTRATION: The study was registered in the German Clinical Trials Register (DRKS00016941) on 09 April 2019.