Sleep-Related Breathing Disorders
Obstructive sleep apnea
OSA results from upper airway collapse during sleep, causing apneas/hypopneas, intermittent hypoxemia, and arousals. Risk factors include obesity, male sex, age, retrognathia, and adenotonsillar hypertrophy in children. Symptoms include snoring, witnessed apneas, and daytime sleepiness. Diagnosis is by PSG or home sleep apnea testing in appropriate patients; AHI ≥5 with symptoms or ≥15 regardless of symptoms defines OSA. Treatment includes CPAP (first-line for moderate-severe disease), mandibular advancement devices, weight loss, positional therapy, and surgery in selected cases.
Central sleep apnea
Central events lack respiratory effort. Cheyne-Stokes respiration occurs in heart failure; treatment targets the underlying cardiac disease and may include adaptive servo-ventilation (avoid in symptomatic heart failure with reduced ejection fraction). Opioid-induced central apnea may respond to CPAP or noninvasive ventilation.
Hypoventilation
Obesity hypoventilation syndrome is defined by BMI ≥30, daytime PaCO2 ≥45 mmHg, and sleep-disordered breathing after excluding other causes. Noninvasive ventilation (bilevel) is often needed rather than CPAP alone.
Traps
Home testing underestimates events and is not ideal with significant cardiopulmonary comorbidity. Do not equate snoring with apnea. In children, OSA is often treated with adenotonsillectomy and PSG is preferred for diagnosis.
Rule of thumb: AHI ≥5 with symptoms, or ≥15 without symptoms, establishes OSA; AHI ≥30 is severe.