Sleep Apnias

Overview of Sleep-Related Diseases

  • Focus on Sleep Apnea

    • Differentiating between types of sleep apnea: obstructive sleep apnea (OSA) and central sleep apnea (CSA)

Obstructive Sleep Apnea (OSA)

  • Definition:

    • OSA is related to an excessive amount of soft tissue in the upper airway, leading to obstruction during sleep.

  • Causes:

    • Commonly associated with:

    • Obesity

    • Increased neck circumference

    • Excessive soft tissue leads to the airway being obstructed as it falls over the tracheal opening.

  • Symptoms:

    • Characterized by a breathing pattern:

    • Breathing occurs, then a period of apnea (cessation of airflow) where breathing stops for over 10 seconds.

    • Repeat breathing pattern may be observed: breathe-breathe-breathe-apnea.

  • Apnea Definition:

    • Defined as the cessation of airflow for greater than 10 seconds during sleep.

  • Physiological Response:

    • As the airway obstructs, blood oxygen levels (SpO2) drop, signaling the body to start breathing again.

  • Treatment:

    • Continuous Positive Airway Pressure (CPAP) is used to stent open the upper airways, preventing obstruction.

  • Apnea-Hypopnea Index (AHI):

    • Measures apneic episodes per hour:

    • 0-4: Normal

    • 5-14: Mild sleep apnea

    • 15-29: Moderate sleep apnea

    • 30 or greater: Severe sleep apnea

    • AHI aids in assessing treatment effectiveness. If AHI remains high while on CPAP, pressure may need to be increased.

  • Simplified AHI Reference:

    • Remember: 5 (Mild) - 15 (Moderate) - 30 (Severe)

    • Expect variable AHI numbers rather than specific clean digits like exactly 30.

Central Sleep Apnea (CSA)

  • Definition:

    • CSA occurs when no signal from the brain is sent to breathe during sleep, leading to the cessation of breathing effort.

  • Causes:

    • Often associated with congenital defects that affect the brain's signaling during sleep.

  • Symptoms:

    • Similar to OSA: breathing pattern is observed (breath-breath-breath-apnea), however, the emphasis is on the absence of breath, not the obstruction.

  • Physiological Response:

    • During apnea:

    • Blood oxygen levels (SpO2) drop.

    • Carbon dioxide (CO2) levels rise.

    • In certain cases, the brain may not initiate breathing again.

  • Treatment Options:

    • Does not utilize CPAP since it is not an obstructive issue:

    • Mechanical ventilation

    • Diaphragmatic pacemakers

    • Pharmacological agents like methylxanthines to stimulate the neural drive to breathe.

Distinguishing Between OSA and CSA

  • Assessment Tools:

    • Sleep studies analyze:

    • Airflow (can be measured as chest or abdominal excursion)

    • SpO2 levels.

  • Identifying OSA:

    • Look for signs of respiratory effort during the apnea periods:

    • If abdominal/chest excursion is present, OSA is likely due to an obstruction.

  • Identifying CSA:

    • If there is no effort or movement during apnea, it indicates CSA as the brain fails to signal.

  • Observational Patterns:

    • Airflow characteristics during apnea will show a clear distinction:

    • OSA: effort to breathe is noted despite obstruction.

    • CSA: no attempt to breathe is noted during apnea.

Conclusion

  • Clear understanding of OSA and CSA is crucial for effective treatment and patient care.

  • This knowledge serves as a foundation for further studies on related diseases, including Guillain Barre and Myasthenia Gravis.