1.3 Obstructive Sleep Apnea
Key Features
Sleep apnea is a cessation of breathing during sleep.
Sleep apnea may be central, obstructive, or mixed.
Obstructive sleep apnea is caused by upper airway collapse and narrowing.
Cardinal symptoms are disruptive snoring, witnessed apneas, and daytime sleepiness.
Obstructive sleep apnea (OSA) is characterized by repetitive episodes of complete (apnea) or partial (hypopnea) upper airway obstruction occurring during sleep. Apnea is a cessation of breathing for at least 10 seconds. Hypopnea is a transient reduction of breathing for less than 10 seconds. Hypopneas must be associated with oxygen desaturation of at least 4%, whereas apneic events are not required to be associated with a decrease in oxygen saturation.
Epidemiology
Estimates of the prevalence of sleep-disordered breathing vary widely in the literature, with most quoting at least 2 to 4% of the general population. Men have a higher prevalence than women (3–8 times), except that risk equalizes in postmenopausal females. The prevalence increases with age and body mass index (BMI) above 25, but it may remain undiagnosed in the majority of patients. Other risk factors include family history, obesity, left ventricular heart failure, advanced age, and allergy.
Clinical
Signs and Symptoms
The signs and symptoms of sleep apnea include witnessed nocturnal apnea events, snoring, daytime sleepiness, headaches, depression, restless sleep, trouble concentrating, irritability, nighttime awakenings or gasping for air, and decreased libido.
Differential Diagnosis
Sleep disturbance and respiratory events can be caused by nonobstructive alveolar hypoventilation, asthma, chronic obstructive pulmonary disease, congestive heart failure, narcolepsy, periodic limb movement disorder, sleep deprivation, and medication, drug, and alcohol use. The differential diagnosis may also include laryngospasm related to gastroesophageal reflux disorder (GERD).
Evaluation
History
The history taken from the patient and his or her bed partner will include reports of snoring, witnessed apneas or gasping events at night, daytime sleepiness, decreased libido or sexual dysfunction, and motor vehicle or work accidents. Bed partner reporting is helpful to evaluate a pretest risk of OSA but is not a good predictor of the severity of sleep-disordered breathing. The Epworth Sleepiness Scale (8 questions scored 0–3) is often used to assess daytime sleepiness; score >11 may correlate with OSA.
Physical Exam
Body habitus (weight, BMI)
Congenital craniofacial abnormalities
Oral exam: large tongue base, elongated soft palate, enlarged uvula, narrow oropharyngeal inlet, modified Mallampati and tonsil staging ( Table 1.4 )
Nasal exam: deviated septum, hypertrophic conchae, polyposis nasi
Facial skeleton abnormalities: e.g., retrognathia, midface hypoplasia, craniofacial anomalies
Neck circumference: men ≥ 17 inches (≥ 43 cm), women ≥ 15.5 inches (≥ 39 cm) is predictive of OSA
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