1. Overview:

• Definition: Sleep apnoea is a sleep disorder characterized by repeated episodes of partial or complete upper airway obstruction during sleep, leading to disrupted sleep and intermittent hypoxia.
• Types:
  • Obstructive Sleep Apnoea (OSA): Most common, due to airway obstruction.
  • Central Sleep Apnoea (CSA): Caused by a failure of the brain to signal the muscles to breathe.
  • Mixed Sleep Apnoea: Combination of obstructive and central features.

2. Epidemiology:

• Prevalence: OSA is common, especially in middle-aged and older adults. The risk is higher in men, obese individuals, and those with certain craniofacial features.
• Risk Factors: Obesity, large neck circumference, craniofacial abnormalities, alcohol and sedative use, smoking, and a family history of OSA.

3. Clinical Presentation:

• Symptoms:
  • Nocturnal: Loud snoring, witnessed apnoeas, gasping or choking during sleep, frequent awakenings.
  • Daytime: Excessive daytime sleepiness (EDS), morning headaches, poor concentration, irritability, and mood disturbances.
• Complications:
  • Cardiovascular: Hypertension, atrial fibrillation, heart failure, myocardial infarction, and stroke.
  • Metabolic: Increased risk of insulin resistance and type 2 diabetes.
  • Psychological: Depression, anxiety, and impaired quality of life.

4. Assessment:

• Epworth Sleepiness Scale (ESS):
  • Purpose: Subjective measure of daytime sleepiness; assesses likelihood of dozing off in various situations.
  • Scoring:
    • 0-9: Normal range.
    • 10-15: Mild to moderate sleepiness, indicative of possible sleep disorder.
    • ≥16: Severe sleepiness, high likelihood of a sleep disorder such as OSA.
• Lung Function Tests:
  • Spirometry: Typically normal in isolated OSA; however, reduced forced expiratory volume (FEV1) and FEV1/FVC ratio may be observed in co-existing obstructive lung disease (e.g., COPD). ~12% of patients with OSA may have a restrictive pattern
  • Nocturnal Oximetry: May show intermittent oxygen desaturations corresponding with apnoeic episodes.

5. Diagnosis:

• Sleep Study (Polysomnography): Gold standard diagnostic test, measuring apnoea-hypopnoea index (AHI), oxygen desaturation, sleep stages, and other parameters.
  • Home Sleep Apnoea Testing (HSAT): An alternative for moderate to severe OSA in uncomplicated cases.
• Apnoea-Hypopnoea Index (AHI):
  • Mild: 5-14 events per hour.
  • Moderate: 15-29 events per hour.
  • Severe: ≥30 events per hour.

6. Management:

• Lifestyle Modifications:
  • Weight Loss: Crucial for reducing OSA severity, particularly in obese patients.
  • Positional Therapy: Avoiding supine sleeping position, which can exacerbate OSA.
  • Avoidance of Alcohol and Sedatives: These can worsen airway obstruction.
• Continuous Positive Airway Pressure (CPAP):
  • First-Line Therapy: Recommended by NICE and BTS for moderate to severe OSA or mild OSA with significant symptoms or cardiovascular comorbidities.
  • Mechanism: Delivers continuous air pressure to keep the airway open during sleep, preventing apnoeic episodes.
  • Settings:
    • Pressure Range: Typically set between 4 and 20 cmH2O; titrated to eliminate apnoeas and hypopnoeas.
    • Auto-CPAP (APAP): Automatically adjusts pressure throughout the night based on detected airway resistance.
    • BiPAP (Bilevel Positive Airway Pressure): Provides higher inspiratory pressure and lower expiratory pressure; used in patients with CSA or those who have difficulty exhaling against CPAP pressure.
  • Duration of Use: CPAP should be used every night for at least 4 hours (ideally the entire sleep duration) to achieve maximum benefit.
• Mandibular Advancement Devices (MADs):
  • Indication: For mild to moderate OSA, particularly in those who are intolerant of CPAP.
  • Mechanism: Holds the lower jaw and tongue forward, increasing airway space.
• Surgical Interventions:
  • Indications: Reserved for patients with significant craniofacial abnormalities or those who fail conservative and CPAP therapies.
  • Procedures: Uvulopalatopharyngoplasty (UPPP), maxillomandibular advancement, and other site-specific surgeries.