COPD-OSA overlap syndrome
The specific diagnosis of OSA in COPD requires some form of overnight sleep study, and there is a growing move toward ambulatory studies that focus on cardiorespiratory variables. Overnight monitoring of oxygen saturation is especially useful, particularly if linked to special analysis software, and may be sufficient in many cases. Full polysomnography can be reserved for select cases where the diagnosis remains in doubt.
Management and outcomes
Nocturnal hypoxemia in patients with COPD benefits from inhaled, long-acting beta-agonist and anticholinergic therapy, and mean nocturnal oxygen saturation is 2% to 3% higher on each medication compared with placebo. Supplemental oxygen may be indicated when nocturnal oxygen desaturation persists despite optimum pharmacotherapy and does not appear to be associated with significant additional risk of hypercapnia.
However, in patients with COPD-OSA overlap, nonnvasive pressure support is the most appropriate management option. In patients with predominant OSA, continuous positive airway pressure therapy (CPAP) is the preferred option, but where COPD is the dominant component, noninvasive ventilation (NIV) in the form of bi-level positive airway pressure (BIPAP) may be more appropriate. Recent reports in severe COPD indicate that NIV targeted to markedly reduce hypercapnia is associated with improved quality of life and prolonged survival (Köhnlein T et al. Lancet Respir Med. 2014;2[9]:698), and patients with COPD with persistent hypercapnia following hospitalization with an acute exacerbation show improved clinical outcomes and survival with continuing home NIV (Murphy PB et al. JAMA. 2017;317[21]:2177).
The recognition of co-existing OSA in patients with COPD has important clinical relevance as the management of patients with overlap syndrome is different from COPD alone, and the long-term survival of patients with overlap syndrome not treated with nocturnal positive airway pressure is significantly inferior to those patients with overlap syndrome appropriately treated (Marin JM et al. Am J Respir Crit Care Med. 2010;182[3]:325).
Dr. McNicholas is with the Department of Respiratory and Sleep Medicine, St. Vincent’s University Hospital, Dublin School of Medicine, University College Dublin, Ireland.
