Sleep-related breathing disorders

Obstructive Sleep Apnea (OSA) - The Airway Blockade

• Pathophysiology: Repetitive collapse of the pharyngeal airway during sleep, leading to apnea (cessation of airflow ≥10s) or hypopnea (↓ airflow by ≥30% with ≥3% O₂ desaturation).
• Risk Factors: Obesity (BMI >30), male gender, age >40, large neck circumference (>17" men, >16" women), alcohol/sedatives, smoking.
• Clinical Presentation: Excessive daytime sleepiness, loud snoring, witnessed apneas, morning headaches, non-restorative sleep.
  • 📌 STOP-BANG screening: Snoring, Tiredness, Observed apnea, high blood Pressure, BMI >35, Age >50, Neck >40cm, Gender male.
• Diagnosis:
  • Gold standard: In-lab polysomnography (PSG).
  • Apnea-Hypopnea Index (AHI):
    • Mild: 5-15 events/hour
    • Moderate: 15-30 events/hour
    • Severe: >30 events/hour
• Management:
  • CPAP (Continuous Positive Airway Pressure): First-line therapy.
  • Lifestyle: Weight loss, positional therapy (avoid supine), avoid alcohol.

⭐ OSA is a major secondary cause of hypertension and is strongly associated with cardiovascular morbidity (e.g., MI, stroke, atrial fibrillation).

Central Sleep Apnea (CSA) - The Brain's Pause Button

• Pathophysiology: Transient ↓ or cessation of respiratory drive from the CNS, leading to absent respiratory effort.
• Key Differentiator from OSA: No effort to breathe during apneic episodes.
• Etiology:
  • Idiopathic: No identifiable cause.
  • Cheyne-Stokes Breathing: Crescendo-decrescendo pattern, often seen in heart failure (CHF).
  • Meds: Opioids are a major precipitant.
  • Neurologic: Stroke, brainstem lesions.
  • High Altitude
• Diagnosis: Polysomnography (PSG) shows cessation of both airflow and respiratory effort (thoracic/abdominal movements).

⭐ Cheyne-Stokes breathing, a specific type of CSA with a cyclical crescendo-decrescendo pattern of breathing and apnea, is strongly associated with advanced heart failure.

Diagnosis & Management - Sleuthing & Solving

• Polysomnography (PSG): Gold standard diagnostic test. Measures Apnea-Hypopnea Index (AHI).
  • Mild OSA: AHI 5-15
  • Moderate OSA: AHI 15-30
  • Severe OSA: AHI >30
• Management Strategy:
  • Positive Airway Pressure (PAP): First-line therapy.
    • CPAP for Obstructive Sleep Apnea (OSA).
    • BiPAP/ASV for Central Sleep Apnea (CSA) or CPAP failure.
  • Adjunctive: Weight loss, positional therapy, avoiding alcohol before bed.
  • Alternatives: Mandibular advancement devices, surgical options (e.g., UPPP).

⭐ Untreated OSA is a significant independent risk factor for developing systemic hypertension and atrial fibrillation.

• Obstructive Sleep Apnea (OSA) results from upper airway collapse, strongly associated with obesity and large neck circumference.
• Diagnosis is confirmed by polysomnography showing an apnea-hypopnea index (AHI) of ≥ 15/hour, or ≥ 5/hour with symptoms.
• CPAP is the first-line treatment; weight loss is a key management component.
• Untreated OSA is a major risk factor for systemic hypertension, arrhythmias, and stroke.
• Central Sleep Apnea (CSA) is characterized by absent respiratory effort, often linked to heart failure or opioid use.