Sleep Apnea, Obstructive (OSA)

BASICS

Definition:
Repetitive episodes of airflow cessation (apnea) during sleep due to pharyngeal obstruction
Causes sleep disruption, excessive daytime sleepiness (EDS), oxygen desaturation, nocturnal hypoxemia
Also called sleep apnea syndrome, nocturnal upper airway occlusion
Systems affected: cardiovascular, nervous, pulmonary

Prevalence:
Moderate/severe OSA:
- Men: 10% (30–49y), 17% (50–70y)
- Women: 3% (30–49y), 9% (50–70y)
Highest rates: obese, hypertensive patients

Pathology:
Passive collapse of naso-/oropharynx during inspiration (anatomic & neuromuscular factors)
Anatomic risk: obesity, soft palate tissue, tonsillar hypertrophy, macroglossia, craniofacial abnormalities, low soft palate, large/posterior tongue
Decreased muscle tone during sleep → airway collapse/obstruction
Triggered/worsened by alcohol, sedatives

Very common: Hypertension, obesity, metabolic syndrome, daytime sleepiness
Less common: Cardiac arrhythmias, heart failure, pulmonary hypertension, nasal obstructive problems

Daytime symptoms:
Excessive daytime sleepiness (EDS): fatigue, especially during quiet activities (reading/TV); severe if during active tasks (work/driving)
Nonrestorative sleep, morning sore/dry throat
Poor concentration, memory/mood issues, headaches, decreased libido, depression
Nighttime symptoms:
Loud snoring (60% of OSA), snorts/gasps, disrupted sleep
Witnessed apneic episodes

Obesity, short/thick neck, large neck circumference
Oropharynx: lateral wall narrowing, tonsillar hypertrophy, macroglossia, micrognathia/retrognathia, high/arched palate, uvular/soft palate changes
Nasopharynx: deviated septum, poor nasal airflow

Lab tests: TSH, CBC (anemia/polycythemia), fasting glucose (obese), ABG (rare)
Gold standard: Polysomnography (PSG)
Shows repetitive apnea/hypopnea with respiratory effort, O2 desaturation
Apneic episodes: ≥10 seconds, ≥10–15/hr, O2 drop = clinically significant
Severity (Apnea-Hypopnea Index, AHI):
Mild: 5–15/hr
Moderate: 15–30/hr
Severe: >30/hr
Split-night PSG: Diagnosis and CPAP titration in one night
Portable/home sleep study: Alternative in select cases

Lifestyle:
Weight loss (adjunct, not curative), exercise
Avoid alcohol, sedatives, smoking
Position therapy (avoid supine position for positional OSA)
CPAP (Continuous Positive Airway Pressure):
Most effective for mild to severe OSA
Multiple mask interfaces (nasal, oral, nasal pillows)
Oral appliances:
Mandibular advancement, tongue-retaining devices
Consider if CPAP intolerant/refusing
Hypoglossal nerve stimulation:
For moderate–severe OSA (AHI 15–65), BMI <35, no concentric collapse at velopharynx
Surgery:
Pediatric OSA with adenotonsillar hypertrophy (tonsillectomy/adenotonsillectomy)
Medications:
No proven effective drugs for OSA

Untreated OSA → ↑ risk of:
Hypertension, stroke, MI, arrhythmias, diabetes, heart failure, driving/work accidents
Unclear if OSA treatment reduces cardiovascular outcomes

Most common cause: tonsillar hypertrophy
Other: obesity, craniofacial, neuromuscular disease
Nighttime: snoring, restlessness, sweating
Daytime: hyperactivity, ↓ school performance
Diagnosis: PSG, abnormal AHI >1/hr
Treatment: surgery for adenotonsillar hypertrophy; CPAP for others