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Predisposing Factors


Anatomically, apnea patients tend to have narrower and more collapsible airway, which worsens with age and weight gain. A retruded mandible can also predispose to OSA,  as do narrow upper arches, since both limit the amount of space available to the tongue and force it to occupy a more backward position during sleep, which narrows the airway.

Other predisposing factors include: (sleep Mm "More" sections)

·         Obesity: excess weight is a major risk factor for sleep apnea, as it can lead to upper airway narrowing  as well as hypoventilation. A 10% weight gain increases the risk of moderate to severe OSA 6 times and is associated with a 32% increase in the AHI index (Mini Board Review Peppard et al Longitudinal Study of moderate weight change and sleep disordered breathing AMA 2000)  . Unfortunately weight loss becomes more difficult in the presence of sleep apnea, as the reduced level of energy makes it more difficult to exercise, and OSA-associated changes in the appetite controlling hormones leptin and ghrelin promote an increase in food intake.  However not all OSA patients fit this description - some patients may be thin but suffer from enlarged tonsils/adenoids or other anatomical airway abnormalities

·         Large Neck Circumference (over 17" males, over 16" in females)

·         Age: most patients with significant sleep apnea are between 40 and 60 years old, but OSA can occur at any age, from infancy to old age

·         Gender: males are twice as likely to suffer from SDB, although that difference narrows after menopause

·         Medications (sedatives or hypnotics)

·         Alcohol: alcohol and benzodiazepines lengthen the duration of apnea episodes by altering  the arousal threshold to hypoxia and hypercapnia, and reduce the activity of the hypoglossal nerve, which controls the upper airway dilators

·         Smoking: the irritation of the pharyngeal tissues by smoking causes swelling which further reduces the size of the airway; smoking also worsen the depth of oxygen desaturations

·         Large tongue

·         Large tonsils/adenoids

·         A low, draping soft palate or large uvula

·         Nasal obstruction

·         Allergies

·         Smoking

·         Mouth breathing

·         Hypothyroidism

·         A family history of SDB

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