Sleep apnea

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ENT/Pulmonology: Sleep Apnea

High-Yield Revision Notes for Board Review & PG Entrance Examinations

Sleep Apnea is a sleep-related breathing disorder characterized by repetitive episodes of partial or complete cessation of breathing during sleep. It is categorized into three primary types: Obstructive (OSA), Central (CSA), and Mixed.

1. Classification of Sleep Apnea

  • Obstructive Sleep Apnea (OSA): The most common form. Caused by a mechanical obstruction of the upper airway while respiratory effort persists.
  • Central Sleep Apnea (CSA): Failure of the respiratory center in the brain to send signals to the respiratory muscles. Commonly associated with heart failure (Cheyne-Stokes respiration) or high-altitude exposure.
  • Mixed Sleep Apnea: A combination of both obstructive and central components.

2. Diagnostic Metrics

The severity is quantified by the Apnea-Hypopnea Index (AHI), calculated via Polysomnography (PSG):

  • Apnea: Cessation of airflow for $\ge 10$ seconds.
  • Hypopnea: \ge 30\% reduction in airflow for $\ge 10$ seconds with at least 3% oxygen desaturation.
  • AHI Interpretation:
    • Normal: < 5 events/hour.
    • Mild: 5 - 15 events/hour.
    • Moderate: 15 - 30 events/hour.
    • Severe: > 30 events/hour.

3. Clinical Pearls & Associations

Condition/Feature High-Yield Detail
Mallampati Classification Used to assess airway; classes III and IV are highly suggestive of difficult airway and OSA risk.
Complications Increased risk of Pulmonary Hypertension (due to chronic hypoxia), Cor Pulmonale, and arrhythmias.
Gold Standard Management CPAP (Continuous Positive Airway Pressure). It prevents airway collapse using positive pneumatic pressure.
Surgical Management Reserved for CPAP intolerance. UPPP (Uvulopalatopharyngoplasty) is the most common procedure.