Health Outcomes With CPAP or NIV in Patients With COPD and a Sleep Related Breathing Disorder

Chronic obstructive pulmonary disease (COPD) is a chronic lung disease affecting an estimated 1 in 10 Canadians. Symptoms include persistent shortness of breath, cough and sputum production. The symptoms can be serious when people with COPD experience a flare of their disease and may lead to hospitalization or death. Improving other conditions that affect COPD control is one way to improve the health of people with COPD. Obstructive sleep apnea (OSA) is the most common breathing problem during sleep, and commonly co-exists with COPD. Although diagnosing and treating OSA is encouraged, it has not been highlighted in guidelines that recommend ideal COPD care. People with COPD and OSA have lower sleep quality and lower oxygen levels during sleep compared to people with OSA. Despite these differences, treatment of OSA in people with COPD is modeled after treatment of OSA in the general population, generally using treatment with continuous positive airway pressure (CPAP) with the possible addition of oxygen through the CPAP machine. There are few studies looking at other types of treatment including noninvasive ventilation (NIV) in people with COPD and OSA. The majority of studies of NIV in COPD has been for people with other reasons to use NIV including acute respiratory failure or chronic hypercarbic respiratory failure and did not include people with risk factors for OSA or who had undergone overnight sleep studies.In Alberta, NIV is provided province wide for people who have both OSA who do not meet certain physiologic targets in their oxygen levels or breathing patterns after CPAP is applied on an overnight sleep study. NIV is provided preferentially to CPAP and oxygen, providing an opportunity to look at health outcomes when NIV is used instead of CPAP for the treatment of patients with COPD. Through this study, we will measure whether people with COPD and a sleep related breathing disorder such as OSA have fewer severe flares of COPD after starting CPAP or NIV. We will evaluate whether the number of Emergency Department visits, hospitalizations or deaths lowers after starting CPAP or NIV.

Inclusion Criteria:Consenting adults who have completed polysomnography at the University of Alberta Sleep Disorders Laboratory in Edmonton, Alberta, Canada.Naïve to CPAP or NIV therapy or have use of CPAP or NIV <4 weeks in the pastDiagnosed with COPD by a respirologist and has fixed airflow obstruction on spirometry (i.e., post-bronchodilator FEV1/FVC <LLN on spirometry or FEV1/FVC <0.70 if the LLN is not provided)Diagnosed with a SRBD for which CPAP or NIV are commonly prescribed, as defined below; some of the patients with mild SRBD or a SRBD suspected to be secondary to COPD rather than OSA (e.g. mild OSA, sustained hypercarbia, hypoxemia etc) may not be prescribed CPAP or NIV at the treating physician's discretionOSA will be defined as a predominantly obstructive apnea-hypopnea index (AHI) ≥5 events/hr of sleep on sleep diagnostic testing in the presence of symptoms/relevant comorbidities or an AHI ≥15 events/hr irrespective of symptoms. If home sleep apnea testing was used in place of polysomnography, the respiratory event index (REI) will be a surrogate of AHI.Hypoventilation will be defined by polysomnography criteria as a sustained elevation in the TcCO2 to be >55 mmHg for ≥10 min or a rise in TcCO2 by >10 mmHg to a value >50 mmHg for ≥10 min. If an arterial blood gas is available, sustained hypercapnia as defined by arterial carbon dioxide oxygen tension (PaCO2) >45 mmHg or serum bicarbonate (HCO3) ≥27 mmol/L while medically stable will be reported.Exclusion Criteria:Significant lung disease in addition to COPDNeuromuscular disease including diaphragmatic paralysisDementiaTreatment with CPAP or NIV for >4 weeks prior to study eligibility.Refusal to participateInability to consent in English and do not have an interpreter readily availableCurrent diagnosis of an active malignancyCentral sleep apnea as the indication for PAP treatment. Central sleep apnea will be defined as a central hypopnea index ≥5 events/hr of sleep on polysomnography and the number of central apneas and/or central hypopneas is >50% of the AHI with or without Cheyne-Stokes breathing