Letter to the Editor Published online: June 3, 2015
Authors’ Reply Emelie Ekkernkamp a Michael Dreher b a Department
of Pneumology, University Hospital, Freiburg, and b Department of Cardiology, Pneumology, Angiology and Intensive Care Medicine, University Hospital Aachen, Aachen, Germany
We totally agree that factors and pathways relating to sleep quality at home in patients with stable hypercapnic chronic obstructive pulmonary disease (COPD) being treated with noninvasive ventilation (NIV) are very complex and that this area needs further investigation. We therefore appreciate Antonio Esquinas’ meaningful comments [1] on our study [2]. It is correct that interindividual variations in lung mechanisms, such as compliance and resistance, might have influenced changes in sleep quality over time. This could have been detected by assessing lung function parameters after each 6-week period, which would have revealed any changes in lung function that occurred during use of the different ventilator strategies. However, the focus of our study was the assessment of sleep quality under NIV in the hospital and at home, and therefore the protocol unfortunately did not include determination of lung function parameters at home. Differentiation between COPD and obesity-hypoventilation syndrome is important in some settings, particularly in studies investigating the underlying mechanisms responsible for positive outcomes in the different diseases. The primary focus of our study was different: to assess differences in sleep quality during periods of ventilation with intelligent volume-assured pressure support (iVAPS) and high-intensity noninvasive positive pressure ventilation (HI-NPPV). Furthermore, the patients in our trial were previously established on NIV for the treatment of confirmed stable hypercapnic COPD diagnosed on the basis of a forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) ratio of
Authors’ Reply Emelie Ekkernkamp a Michael Dreher b a Department
of Pneumology, University Hospital, Freiburg, and b Department of Cardiology, Pneumology, Angiology and Intensive Care Medicine, University Hospital Aachen, Aachen, Germany
We totally agree that factors and pathways relating to sleep quality at home in patients with stable hypercapnic chronic obstructive pulmonary disease (COPD) being treated with noninvasive ventilation (NIV) are very complex and that this area needs further investigation. We therefore appreciate Antonio Esquinas’ meaningful comments [1] on our study [2]. It is correct that interindividual variations in lung mechanisms, such as compliance and resistance, might have influenced changes in sleep quality over time. This could have been detected by assessing lung function parameters after each 6-week period, which would have revealed any changes in lung function that occurred during use of the different ventilator strategies. However, the focus of our study was the assessment of sleep quality under NIV in the hospital and at home, and therefore the protocol unfortunately did not include determination of lung function parameters at home. Differentiation between COPD and obesity-hypoventilation syndrome is important in some settings, particularly in studies investigating the underlying mechanisms responsible for positive outcomes in the different diseases. The primary focus of our study was different: to assess differences in sleep quality during periods of ventilation with intelligent volume-assured pressure support (iVAPS) and high-intensity noninvasive positive pressure ventilation (HI-NPPV). Furthermore, the patients in our trial were previously established on NIV for the treatment of confirmed stable hypercapnic COPD diagnosed on the basis of a forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) ratio of
