Chronic Obstructive Pulmonary Disease-Obstructive Sleep Apnea Overlap: More Than a Casual Acquaintance

• Type of Material: Article
• Authors: Octavian Ioachimescu, Emory University; Walter T. McNicholas, University College Dublin
• Language: English
• Date: 2022-07-15
• Publisher: AMER THORACIC SOC
• Publication Version: Final Published Version
• Copyright Statement: © 2022 by the American Thoracic Society
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1164/rccm.202204-0695ED
• Title of Journal or Parent Work: AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
• Volume: 206
• Issue: 2
• Start Page: 139
• End Page: 141
• Keywords: General & Internal Medicine; Science & Technology; Life Sciences & Biomedicine; Respiratory System; Critical Care Medicine
• Research Categories: Health Sciences, General

Abstract

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) each affect at least 10% of the adult general population and thus, the two disorders occurring together, often referred to as the overlap syndrome, is likely to be common based on chance association alone. Some factors relating to COPD such as malnutrition leading to low body mass, hyperinflation associated with a low diaphragmatic position (increased “tracheal tug”), reduced REM sleep, upright sleep position, and potentially age factors can decrease the likelihood of OSA. Conversely, other variables such as weight gain, cigarette smoking, medications, rostral fluid shifts in recumbent position, higher diaphragmatic position, etc., can predispose to OSA (2). Additionally, OSA predisposes to lower airway inflammation, which in turn may promote the development of COPD (Figure 1). Both COPD and OSA generate local and systemic inflammatory responses that may lead to cardiovascular morbidity and, thus, the overlap syndrome should be expected to be associated with an increased likelihood of cardiovascular disease compared with either disorder alone (3). While pulmonary hypertension has long been recognized as a common finding in overlap patients, likely due to more severe diurnal hypoxemia than patients with COPD alone (4), epidemiological data on the prevalence of other co-morbidities are limited. However, Kendzerska and colleagues recently reported more severe nocturnal oxygen desaturation in addition to higher rates of cardiovascular morbidity and all-cause mortality in overlap syndrome compared with patients with COPD or OSA alone (5). The importance of recognizing co-existing OSA in patients with COPD is reinforced by a report that, in a rodent model, cardiovascular changes induced by chronic intermittent hypoxia can be reversed by normoxia (6).