Obstructive Sleep Apnoea
Obstructive sleep apnoea (OSA) is a common sleep disorder, characterized by complete or partial airway obstruction and caused by pharyngeal collapse during sleep. The resultant complete cessations of breathing are called apnoeas if their duration is 10 s
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Ruzica Jokic
12.1 Definitions of Obstructive Sleep Apnoea (OSA) Obstructive sleep apnoea (OSA) is a common sleep disorder, characterized by complete or partial airway obstruction and caused by pharyngeal collapse during sleep. The resultant complete cessations of breathing are called apnoeas if their duration is 10 s or more. Hypopnoeas are a result of reduced inspiratory flow when the airway narrows but does not fully collapse (Strollo and Rogers 1996). OSA syndrome is defined as (1) five or more episodes of apnoea or hypopnoea per hour of sleep (apnoea-hypopnoea index—AHI) with associated symptoms (e.g., excessive daytime sleepiness, fatigue or impaired cognition) or (2) AHI equal to or higher than 15, regardless of associated symptoms (Anon 1999).
12.2 Epidemiology and Risk Factors Patients with severe OSA are often referred to sleep laboratories for investigations and confirmation of diagnosis. Epidemiological studies show that 4% of men and 2% of women aged 50 years or older suffer from symptomatic OSA. However, the prevalence of mild or moderate OSA in individuals who frequently do not present with typical symptoms of the disorder is estimated to be as high as 20–30% of the middle-aged population (Young et al. 1997). Thus, despite increased awareness over the last few decades, the availability of diagnostic tools as well as knowledge of its significant impact on daytime function and quality of life, OSA commonly remains an unrecognized and underdiagnosed disorder.
R. Jokic, M.D. F.R.C.P. (C), Ph.D. Department of Psychiatry, Queen’s University and Providence Care Hospital, Kingston, ON, Canada e-mail: [email protected] © Springer-Verlag GmbH Germany, part of Springer Nature 2018 H. Selsick (ed.), Sleep Disorders in Psychiatric Patients, https://doi.org/10.1007/978-3-642-54836-9_12
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214 Table 12.1 Common risk factors for OSA
R. Jokic Obesity Male sex Middle age or older Micronagthia and retrognathia Large neck circumference Nasal allergies and stuffiness
Recent studies emphasize that the number of patients diagnosed as suffering from OSA has increased dramatically in the last few years and will continue to do so in the coming years (Leger et al. 2012). The major risk factors for OSA are listed in Table 12.1. Obesity is one of the most important risk factors for OSA. It has been determined that a 10% weight gain increases the risk of developing OSA sixfold. A recent longitudinal study that investigated the link between weight gain and OSA confirmed that increased adipose tissue in the region of the neck, fat infiltration and oedema in the soft palate associated with moderate weight change all had an impact on sleep- disordered breathing (Peppard et al. 2000). The risk of OSA increases with age. Men have a higher prevalence of OSA than women, and abdominal fat and higher neck-to-waist ratios are significantly associated with the severity of OSA in men. Females are found to have less severe OSA at all ages. Menopause, pregnancy and polycystic ovarian syndrome increase the risk for OSA in
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