Obstructive Sleep Apnea ( Osa )

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Obstructive sleep apnea: Obstructive sleep apnea (OSA) is a sleep–breathing disorder characterized by momentary episodes of either complete breathing cessation for periods of ten seconds or more (apnea) or significant reductions in breathing amplitude (hypopnea) caused by a collapsed or obstructed airway; these two conditions can lead to hypoxemia (low levels of oxygen in blood) and hypercapnia (high levels of carbon dioxide in blood). Patients are categorized as having mild, moderate or severe OSA depending on the apnea/hypopnea index (AHI), which is defined as the total numbers of apnea/hypopnea episodes per hour of sleep. In normal individuals the index is usually 5 or lower, 5-15 in mild, 15-30 in moderate and 30 or more in severe OSA patients (1, 2). In patients with mild OSA the oxyhemoglobin saturation drops to 95% and can drop below 80% in severe cases. Obstruction of the airways results in greater breathing effort and fluctuations in intrathoracic pressure, resulting in arousal, sleep interruption and reopening of the airway (3). Risk factors for sleep apnea include obesity, craniofacial abnormalities, smoking, male gender, short neck, and menopause in women. Obesity is one of the main risk factors of sleep apnea since 60% to 90% of OSA patients are obese and there is a strong positive correlation between body mass index (BMI) and OSA (4, 5). The overlap of obesity and OSA poses a challenge to ascribing the relative contributions of these comorbidities to
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