Sleep Apnea

Snapshot

• A 49-year-old man with morbid obesity presents to the clinic complaining of heart palpitations and a pre-syncopal episode. An EKG at the office demonstrates some premature ventricular beats. The patient states that he feels more tired than usual, and it is difficult to stay awake lately. He denies any rhythmic jerking, chest pain, or shortness of breath. Physical examination was unremarkable.

Introduction

• Clinical definition
  • sleep breathing disorder characterized by repeated cessation of breathing during sleep
  • results in sleep disruption and consequent daytime fatigue
  • subtypes 
    • obstructive sleep apnea (OSA)
      • most common form characterized by the relaxation of throat muscles leading to a reduced/cessation of airflow despite a respiratory drive
    • central sleep apnea (CSA)
      • decreased central nervous system respiratory drive leading to decreased airflow and ventilatory effort during sleep
• Epidemiology
  • demographics
    • OSA is 2-3 times more common in males than females
    • OSA is more prevalent in African Americans
  • risk factors  
    • age
    • male gender
    • obesity
    • craniofacial and upper airway abnormalities
    • chronic medical conditions (e.g., stroke)
    • medication use (e.g., opioids)
• Pathogenesis
  • CSA
    • primary (e.g., idiopathic)
    • secondary (e.g., drug use)
    • commonly associated with Cheyne-Stokes breathing, especially among patients who have heart failure or stroke
  • OSA 
    • recurrent, functional collapse of the airway during sleep leading to reduced or complete cessation of airflow with breathing efforts
• may occur secondary to decreased pharyngeal muscle tone, obese neck, or large tone size

Presentation

• Symptoms
  • loud snoring
  • morning headache
  • difficulty staying asleep
  • excessive daytime fatigue/sleepiness 
• Physical exam
  • hypertension  
  • obesity
  • large neck circumference 
  • crowded oropharynx 
• micrognathia 

Studies

• Home sleep apnea testing
  • acceptable alternative for patients strongly suspected of OSA without medical comorbidities
• In laboratory polysomnography
  • gold standard diagnostic test for sleep apnea
  • differentiates OSA from CSA
• Laboratory studies 
  • polycythemia 
    • due to chronic hypoxia stimulating EPO release
    • usually mild if no daytime hypoxemia
• Diagnostic criteria
  • OSA
    • 15 obstructive apneas/hour
• 5 apneas/hour and snoring/breathing pauses with daytime somnolence

Differential 

• Narcolepsy
  • distinguishing factor
    • clinical features such as cataplexy, hypnagogic hallucinations, sleep attacks, and sleep paralysis
    • can be differentiated on polysomnography  
• Respiratory disease (e.g., chronic obstructive lung disease)
  • distinguishing factor
•  positive medical history and polysomnography results   

Treatment

• OSA
  • lifestyle 
    • weight loss, exercise, sleep position change, smoking cessation, abstain from alcohol, and avoid certain medications
  • medical 
    • positive airway pressure therapy
      • first-line treatment 
      • continuous positive airway pressure (CPAP) is the most common form  
    • oral appliances (e.g., mandibular advancement devices)
      • indicated in patients with mild to moderate OSA who fail positive airway pressure therapy or prefers such treatment
  • surgical treatment
    • indicated in patients with severe, obstructing lesions of the upper airway who have failed initial therapy
• CSA
  • medical 
    • correction of conditions that may be causing or exacerbating the condition (e.g., stop taking opioids)
• positive airway pressure therapy (e.g., BiPAP) for mechanical ventilation

Complications

• Arrhythmias
  • non-sustained ventricular tachycardia, atrial fibrillation, and ventricular ectopy
  • bradycardia and asystole
  • may result in sudden death
• Daytime fatigue (increased risk for motor vehicle accidents)
• Pulmonary hypertension
  • may result in mild pulmonary hypertension, but not definitively cor pulmonale if no daytime hypoxemia is present 
• Type 2 diabetes and other metabolic conditions 
• Severe OSA may be associated with CAD
• Right ventricular failure