New Research on COPD-OSA Overlap Syndrome

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New Research on COPD-OSA Overlap Syndrome

By Admin

New research supported by ResMed and the American Thoracic Society seeks to address the specific health conditions of COPD-OSA Overlap Syndrome. This syndrome, characterized by a higher morbidity and mortality than either condition alone, is showing an increasing prevalence in sleep apnea patient populations. One researcher in particular, Dr. David Geoffrey Chapman, BSc, PhD, of the University of Technology in Sydney, Australia, was awarded $100,000 by the new ATS Foundation/ResMed Research Fellowship in Sleep-disordered Breathing and PAP Therapy. These grants will help advance our knowledge of how CPAP and noninvasive ventilation (NIV) can help improve sleep and health for those with COPD-OSA Overlap Syndrome. Specifically, the research will determine how effective NIV is in addressing problems such as hyperinflation, the act of breathing at high lung volumes that is common in people with this condition. According to studies by the ATS, one in four people with COPD also have moderate to severe OSA.

What is COPD?

Chronic Obstructive Pulmonary Disease (COPD) is a chronic inflammatory lung disease that obstructs airflow into the lungs. Symptoms include breathing difficulty, coughing or wheezing, and excessive buildup of fluids. Generally, COPD is used to describe the progressive conditions of emphysema, chronic bronchitis, and refractory (non-reversible) asthma. Often caused by exposure to noxious gases or pollution, COPD increases the risk of developing heart disease, lung cancer and a variety of other conditions. Emphysema (damage of the alveoli, or air passages of the lungs) and chronic bronchitis (inflammation of the lining of the bronchial tubes) are the two most common conditions that contribute to COPD. According to research published by Thorax on the BMJ website, COPD is the fourth leading cause of death in the United States. This is often a result of cigarette smoking, but COPD can also be caused by pollution or exposure to chemical gases or particulate matter. In patients with sleep apnea, COPD is known to exacerbate the symptoms and increase the likelihood of other comorbidities.

What is Overlap Syndrome?

While the term overlap syndrome is used more generally to describe a combination of diseases or disorders, the use of the term to describe the coexistence of obstructive sleep apnea (OSA) and Chronic Obstructive Pulmonary Disease (COPD) was first coined by researcher David Flenley when he recognized a high prevalence of OSA in COPD patients. In recent years this prevalence has increased, resulting in part from improved diagnostic capabilities and more public awareness of the condition, but also due to a genuine rise in the condition among patient populations. A recent study shows that up to 66% of the COPD patients who enrolled in a pulmonary rehabilitation program tested positive for OSA. Conversely, clinical records show that OSA patients have a high rate of COPD diagnosis, either during initial sleep studies, or resulting from follow-up assessments during OSA treatment. While there is still a lot we don’t know about how COPD and OSA overlap, it is clear that the syndrome exacerbates symptoms of both conditions, prolongs oxygen desaturation during sleep, and increases the chance for mortality. With such severe risks involved, there is no question that more attention should be given to the disorder, both in research dollars and in public awareness.

The Research

Since its inception, the ATS Foundation Research Program has awarded $19.3 million to 263 investigators, both in the U.S. and internationally. These researchers have gone on to receive millions of dollars in federal funding. Known as “seed” support, this initial funding increases the chance for researchers to receive subsequent grants from the federal government, thereby advancing our understanding of often complicated comorbid conditions in pulmonary diseases and sleep disordered breathing. Research on COPD/OSA Overlap Syndrome helps us to better understand the relationship between these two diseases, as well as improve the technology and equipment used to treat and assess patients, and determine which therapy options are best for them. Dr. Chapman’s research in particular will help to determine how to best treat sleep-disordered breathing in patients with COPD-OSA Overlap Syndrome, developing tools for precisely tailored therapies to reduce the complications associated with both diseases. COPD and OSA are both leading causes of death in the U.S., and sleep disordered breathing is a risk factor for premature death in either case. However the two diseases are related, it is clear that complications arise during sleep that are critical to patient health and therapy needs. Because of this, research grant foundations like ResMed’s Research Fellowship and the ATS Foundation Research Program recommend studies that improve our understanding of gas exchange impairment during sleep. These studies, such as Dr. Chapman’s work with COPD and OSA, could potentially help to guide definitions of the various respiratory events associated with comorbid conditions. Carlos M. Nunez, MD, ResMed’s Chief Medical Officer, gave a statement regarding the new research grants, emphasizing the importance of the ATS Foundation and its contribution to medical science. “The more that researchers can confirm how sleep apnea and comorbid conditions interact,” Nunez said, “the more focused and motivated the medical community should be to identify those who are suffering and get them screened, diagnosed, and effectively treated as soon as possible.”

Clinical Implications of Overlap

Patients with both COPD and OSA have two conditions working against them during sleep. Both conditions cause oxygen desaturation, and patients with Overlap Syndrome are at more risk for prolonged hypoxemia than those with either condition on its own. This also increases morbidity and mortality, as patients with Overlap Syndrome have two diseases with high rates of comorbidity and high risk for exacerbated health conditions such as heart disease, stroke, and cancer. In one study, 86% of patients with COPD-OSA overlap had pulmonary hypertension, compared with just 16% of those with sleep apnea alone. Pulmonary hypertension is high blood pressure that is concentrated in the arteries that supply the lungs, and as a condition associated with both OSA and COPD, is an example of potentially severe comorbidities in Overlap Syndrome. The study went on to explain how a COPD diagnosis, along with its markers such as reduced FEV1 (spirometry) or cigarette smoking, are linked with increased mortality in OSA patients. In fact, a COPD diagnosis is a 7-fold risk of death for those who already have sleep apnea. With such risks to life and well being, and a rising prevalence in patient populations, there is no question that further research is needed to better understand the condition.

Treatment and Management

A main focus of the new research on COPD and OSA overlap is the proper use of CPAP or noninvasive pressure support, with or without associated O2 therapy. In most patients with COPD-OSA overlap, forms of NIV such as bi-level positive airway pressure, or BIPAP, will be the most appropriate treatment, though a number of medications, lifestyle changes, and rehabilitation programs may be included in the recommendations. In patients with predominant OSA, standard CPAP may be preferred, but when COPD is the dominant disease, a BiPAP or other NIV mode will be needed for ventilation support. The term NIV is often used interchangeably with BiPAP (Bilevel Positive Airway Pressure), which is the most common form of NIV used for both COPD and OSA. BiPAP delivers different air pressure levels during inspiration and expiration. In this way, ventilation is provided by inspiratory pressure (iPAP), while expiratory pressure (ePAP) helps to recruit collapsed alveoli for improved gas exchange. The dual pressure system is highly effective in supporting the lungs as well as the airway. While there are a number of different ventilation support options for moderate to severe COPD, clinical studies on the use of BiPAP for patients with both COPD and OSA show high rates of success. One of the goals of the new research is to establish how specific NIV settings and other forms of therapy best suit the needs of the various manifestations of COPD-OSA overlap. With more tailored approaches to treatment, we can greatly decrease the risk of apnea events, damaging hypoxemia, and mortality, while at the same time providing a more comfortable sleeping experience.