O bstructive sleep apnea (OSA) is characterized by recurring episodes of cessation (apnea) or reduction (hypopnea) in airflow during sleep caused by obstruction of the upper airway. In recent population-based studies, the estimated prevalence of moderate to severe sleep-disordered breathing ranges from 3% to nearly 50% depending on age group and sex. 1,2 A survey conducted by the Public Health Agency of Canada in 2009 found that 26% of Canadian adults reported symptoms and risk factors that are associated with a high risk of OSA; 3 however, prevalence data in Canada are limited by the absence of studies using objective sleep testing. Obstructive sleep apnea may be underdiagnosed; only 3% of Canadians aged 18 years or older reported a formal diagnosis despite high rates of symptom reporting; 3 yet, high-quality prospective studies have shown clear benefit of treatment for patients with sleepiness, cognitive or psychological dysfunction, or poor quality of life owing to obstructive sleep apnea. 4-6 Large population-based studies have shown that untreated moderate or severe OSA is associated with serious complications. 7-9 We review signs, symptoms and morbidity associated with OSA, along with diagnostic options, treatments and considerations for long-term follow-up, based on evidence and recommendations from clinical guidelines, systematic reviews and primary studies (Box 1). What signs, symptoms and risk factors should prompt consideration of obstructive sleep apnea? About 25% of patients with OSA report daytime sleepiness; a greater proportion report unrefreshing sleep or fatigue. 10 Other symptoms include frequent nocturnal waking due to choking or gasping, nocturia, morning headaches, poor concentration, irritability and erectile dysfunction. 11-13 Bed partners may report snoring or witnessed apneas. Atypical symptoms, which are more frequently reported by women, include insomnia, impaired memory, mood disturbance, reflux and nocturnal enuresis. 14 However, the correlation of symptoms with disease severity is poor, 15 which is why it is important for physicians to be alert to milder symptoms. There are many underlying risk factors, predisposing conditions and associated comorbidities for OSA; they are summarized in Appendix 1, available at www.cmaj.ca/ lookup/suppl/

Elevated levels of circulating CD4(+) CRTh2(+) T cells are a feature of severe asthma, despite high-dose corticosteroids. Tracking the systemic level of these cells may help identify type 2 severe asthmatics at risk of exacerbation.

Chronic obstructive pulmonary disease (COPD) is a chronic, progressive lung disease resulting from exposure to cigarette smoke, noxious gases, particulate matter, and air pollutants. COPD is exacerbated by acute inflammatory insults such as lung infections (viral and bacterial) and air pollutants which further accelerate the steady decline in lung function. The chronic inflammatory process in the lung contributes to the extrapulmonary manifestations of COPD which are predominantly cardiovascular in nature. Here we review the significant burden of cardiovascular disease in COPD and discuss the clinical and pathological links between acute exacerbations of COPD and cardiovascular disease.