Nocturnal non-invasive positive pressure ventilation for COPD

Abstract

There is an ongoing discussion on whether long-term non-invasive positive pressure ventilation (NPPV) should be used in chronic hypercapnic chronic obstructive pulmonary disease (COPD) patients. Early trials had failed to show convincing physiological and clinical effects using NPPV with assisted modes of ventilation and rather low inflation pressures. In particular, long-term survival could not be improved and findings on health-related quality of life had been conflicting. Remarkably, high-intensity NPPV using higher inflation pressures and back-up rates has recently been shown to be capable of improving blood gases, lung function, and health-related quality of life. Subsequently, a large study using this technique also showed a substantial improvement in the prognosis in these patients. Therefore, there is now increasing evidence to support physiologically effective NPPV in hypercapnic COPD patients, but how to best select patients still needs to be defined. The present article summarizes the physiological background and the current evidence on NPPV in COPD in addition to future considerations.

Keywords:

• COPD
• exacerbation
• exercise capacity
• hypercapnia
• lung function non-invasive ventilation
• oxygen
• quality of life
• questionnaire
• survival

Financial & competing interests disclosure

W Windisch received open research grants from Weinmann, Germany; Vivisol, Germany; VitalAire, Germany; Respironics, USA; Breas Medical, Sweden. W Windisch receives speaking fees from and is on the editorial board for Heinen und Löwenstein, Germany; VitalAire, Germany; ResMed, Germany; Maquet, Germany; Respironics, USA/Germany; Fischer and Paykel Healthcare, Germany; Linde, Germany and Radiometer, Germany. JH. Storre receives open research grants from Weinmann, Germany; Vivisol, Germany; VitalAire, Germany. JH Sorre receives speaking fees from Heinen und Löwenstein, Germany; VitalAire, Germany; ResMed, Germany; Respironics, USA/Germany; Fischer and Paykel Healthcare, Germany; Radiometer, Germany; Sentec, Switzerland and Breas Medical, Deutschland. T Köhnlein receives open research grants from Weinmann, Germany; Resmed Germany; Tyco Healthcare, Germany, Deutsche Lungenstiftung [German Lung Foundation]. T Köhnlein receives speaking fees from and is on the editorial boards for Heinen und Löwenstein, Germany; ResMed, Germany; Boehringer Ingelheim, Germany; Novartis, Germany and, Grifols, Germany. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• Chronic respiratory failure in COPD patients refers to either chronic pulmonary failure with the key finding of hypoxemia (Type 1 respiratory failure), to chronic ventilatory failure with key finding of hypercapnia in addition to hypoxemia (Type 2 respiratory failure), or to both.

• Both conditions can lead to severe dyspnea. In addition, chronic ventilatory failure can additionally produce different symptoms, such as sleep-disordered breathing, recurrent infection, and symptoms related to hypercapnia-induced dilation of the vessels: morning headache, vasodilatation visible in the conjunctiva of the eyes, and, importantly, peripheral edema.

• While chronic pulmonary failure treated by long-term oxygen therapy is recognized with an improved outcome, long-term non-invasive positive pressure ventilation (NPPV) is a promising treatment option for those patients with chronic ventilatory failure and, consequently, chronic hypercapnia.

• The physiologic goal of long-term NPPV is to augment reduced alveolar ventilation as evidenced by a reduction in partial pressure of carbon dioxide (PaCO₂). This, in turn, should clinically translate to a reduction in symptoms, an improvement in health-related quality of life, and, at best, an improved long-term survival.

• There has, however, been an ongoing discussion on the usefulness of long-term NPPV in COPD patients, since earlier studies failed to convincingly demonstrate both physiologic and clinical effects.

• More recent data have clearly outlined that more aggressive forms of NPPV using adequate inflation pressures of >18 cmH₂O, typically ranging between 20 and 30 cmH₂O, and higher back-up rates are required for both physiological and clinical effectiveness of NPPV, and this approach of NPPV aimed at normalizing PaCO₂ has been labeled ‘high-intensity NPPV’. Higher baseline PaCO₂ values and longer periods spent on NPPV increase the likelihood for a success of NPPV.

• Most recent research has now established a clear survival benefit gained by long-term NPPV when started during stable disease in chronically hypercapnic COPD patients.

• In addition, current research finding has also documented a significant improvement in rehabilitation outcome and health-related quality of life, which should be measured by instruments specifically designed for patients with chronic respiratory failure due to COPD; here, the Severe Respiratory Insufficiency Questionnaire has been established as the internationally available standard tool.

• It is, however, still unclear whether NPPV is also capable of reducing the rate of rehospitalization of acute exacerbation following acute episodes of respiratory failure that have required mechanical ventilation in the hospital. Patients with spontaneously resolving hypercapnia following recovery from exacerbation do not seem to be benefiting candidates, but the usefulness of NPPV in patients with really persisting hypercapnia following episodes of acute respiratory failure still needs to be elucidated.

• Furthermore, unmet needs refer to the crucial question of how to best select candidates for long-term NPPV. Finally, long-term NPPV as carefully commenced in hospital is expensive, and further research is required to evaluate cost-saving outpatient commencement of NPPV.

Notes