Sleep Apnea

Source: Dopp JM, Phillips BG. Sleep Disorders. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=7990389. Accessed June 3, 2012.

• Repetitive episodes of cessation of breathing during sleep.

• Obstructive sleep apnea results from relaxation of soft tissue in back of throat during sleep, blocking airway.
• Central sleep apnea occurs when brain does not signal muscles that control breathing.
• Complex sleep apnea is combination of obstructive sleep apnea and central sleep apnea.

• Obstructive sleep apnea caused by upper airway obstruction secondary to loss of pharyngeal muscle tone during sleep.
• Central sleep apnea caused by temporary loss of respiratory effort during sleep due to autonomic nervous system lesions, neurologic diseases, high altitudes, or heart failure.
• Contributing factors include:
  • Obesity
  • Upper airway lesions
  • Enlarged tonsils
  • Amyloidosis
  • Hypothyroidism
• Apneic episodes terminated by a reflex action in response to fall in blood oxygen saturation that causes brief arousal, during which breathing resumes.

• Prevalence in US adult population: 4% in males and 2% in females.
• More common in African Americans and less common in Asians.
• Can occur in children and adolescents.

• Obesity
• Cigarette smoking
• Hypothyroidism
• Ingestion of alcohol or sedatives before sleep and nasal obstruction may precipitate or worsen condition.

Signs and Symptoms

• Complaints of:
  • Daytime somnolence or fatigue
  • Morning headache
  • Poor memory
  • Irritability
• History of loud snoring with witnessed apneic events.
• May have systemic hypertension.
• Severe episodes involve:
  • Heavy snoring
  • Severe gas exchange disturbances
  • Respiratory failure, causing gasping.
  • Episodes may occur up to 600 times/night.
• Complications include:
  • Arrhythmias
  • Hypertension
  • Cor pulmonale
  • Sudden death

Diagnostic Procedures

• Overnight polysomnography shows apneic episodes with hypoxemia.

• Relieve signs and symptoms.
• Eliminate sleep-disordered breathing.

• Weight loss in all overweight patients.
• Nasal positive airway pressure (PAP), which may be continuous or bilevel.
• Surgical therapies include tonsillectomy and nasal septal repair; uvulopalatopharyngoplasty and tracheostomy may be necessary in severe cases.

• Obstructive sleep apnea
  • Avoidance of CNS depressants and drugs that promote weight gain. Angiotensin-converting enzyme (ACE) inhibitors can also worsen sleep-disordered breathing.
  • Modafinil FDA approved to improve wakefulness in patients with residual daytime sleepiness while on PAP. Use only in patients using optimal PAP therapy and free of cardiovascular disease.
• Central sleep apnea
  • PAP with or without supplemental oxygen.
  • Acetazolamide causes metabolic acidosis that stimulates respiratory drive and may be beneficial for high altitude, heart failure, and idiopathic causes.

• Evaluate patients with OSA after 1–3 months of treatment for improvement in:
  • Alertness
  • Daytime symptoms
  • Weight reduction
• Ask bed partner to report on episodes of snoring and gasping.

• Can be managed successfully in many patients.
• Untreated sleep apnea increases risk of:
  • Hypertension
  • Myocardial infarction
  • Stroke
  • Diabetes mellitus
• May increase likelihood of having work-related or driving accidents.