Obstructive Sleep Apnea (OSA)
Recurrent upper airway collapse during sleep causing apnea, hypoxia, and fragmented sleep.
Also known as: OSA, obstructive sleep apnea, sleep apnea, OSAS, sleep-disordered breathing
Overview
Sleep-related breathing disorder characterized by recurrent episodes of upper airway collapse during sleep with associated reductions in airflow (hypopnea) or complete cessation (apnea), leading to oxyhemoglobin desaturation and sleep fragmentation.
Epidemiology
Estimated to affect ~25% of US adults at any level (AHI >=5) by current criteria, with moderate-severe disease (AHI >=15) in roughly 10-15% (~13% of men, ~6% of women); the majority are undiagnosed. Strong male predominance pre-menopause; gender gap narrows after menopause.
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Risk factors
- Obesity (BMI ≥30) — strongest modifiable risk factor
- Male sex, postmenopausal status in women
- Increasing age
- Anatomic: short/thick neck (>17 in men, >16 in women), retrognathia/micrognathia, macroglossia, tonsillar hypertrophy, nasal obstruction
- Family history
- Alcohol, sedatives, opioids (reduce upper airway tone)
- Hypothyroidism, acromegaly, Down syndrome
- Smoking
Pathophysiology
Reduced upper airway muscle tone during sleep + anatomic narrowing → collapse during inspiration → apnea/hypopnea → arousal to restore patency → fragmented sleep. Resulting intermittent hypoxia, sympathetic surges, and oxidative stress drive cardiovascular and metabolic consequences.
Clinical presentation
Symptoms
- Loud habitual snoring with witnessed apneas (gold-standard partner-reported feature)
- Excessive daytime sleepiness (Epworth Sleepiness Scale >10)
- Choking/gasping awakenings, restless sleep
- Morning headaches, dry mouth
- Nocturia, nocturnal sweating
- Concentration and memory deficits, mood changes (irritability, depression)
- Decreased libido, erectile dysfunction
Signs / physical exam
- Obesity, large neck circumference
- Crowded oropharynx (Mallampati III-IV), retrognathia, enlarged tonsils, deviated septum
- Hypertension (often resistant) — common comorbidity
- Atrial fibrillation, polycythemia in severe cases
Differential diagnosis
- Central sleep apnea — Absent respiratory effort during apnea (vs OSA which has effort against closed airway); seen in HF, opioids, high altitude, brainstem lesions
- Obesity hypoventilation syndrome (Pickwickian) — Daytime hypercapnia (PaCO2 >45) + BMI ≥30 — often coexists with OSA; treated with BiPAP or AVAPS
- Narcolepsy — Excessive daytime sleepiness + cataplexy, sleep paralysis, hypnagogic hallucinations; MSLT with sleep-onset REM
- Insomnia — Difficulty initiating/maintaining sleep without breathing-related arousals; normal AHI
- Restless legs syndrome / periodic limb movement disorder — Urge to move legs at rest; periodic limb movement index elevated on PSG
- Hypothyroidism — Daytime sleepiness, weight gain, cold intolerance; elevated TSH
Diagnostic workup
Diagnostic criteria
AASM 2014: Symptoms (sleepiness, fatigue, snoring/apneas, awakening with gasping, hypertension, mood/cognitive dysfunction) PLUS ≥5 obstructive events/hour on PSG; OR ≥15 events/hour regardless of symptoms.
Labs
- TSH if hypothyroidism suspected
- CBC (polycythemia in severe hypoxemia)
- HbA1c (high diabetes comorbidity); lipid panel
- ABG if hypoventilation suspected (PaCO2 >45 → obesity hypoventilation)
Imaging
- Imaging not routinely indicated
- Cephalometric imaging or upper airway endoscopy for surgical planning
Other studies
- Screening: STOP-BANG questionnaire (Snoring, Tiredness, Observed apneas, BP, BMI, Age, Neck, Gender)
- In-laboratory polysomnography (PSG) — gold standard: measures AHI, oxygen saturation, sleep stages, leg movements
- Home sleep apnea testing (HSAT) — acceptable for high pretest probability without significant comorbidities; type III device monitoring airflow, effort, oximetry
- Severity by Apnea-Hypopnea Index (AHI): mild 5-14, moderate 15-29, severe ≥30 events/hour
Diagnostic algorithm
| AHI (events/h) | Severity | Typical Management |
|---|---|---|
| <5 | Normal | Lifestyle counseling if snoring; reassess if symptoms |
| 5-14 | Mild | Lifestyle + CPAP or oral appliance; consider symptom-based |
| 15-29 | Moderate | CPAP first-line; oral appliance/hypoglossal stim if intolerant |
| ≥30 | Severe | CPAP first-line; aggressively treat comorbidities; consider surgery if refractory |
Treatment
First-line
- Behavioral: weight loss (5-10% body weight can substantially reduce AHI), positional therapy (avoid supine sleep), alcohol/sedative avoidance, smoking cessation
- Continuous positive airway pressure (CPAP) — first-line and most effective for moderate-severe OSA; auto-titrating or fixed pressure
- BiPAP for CPAP intolerance, very high pressure requirements, or coexistent hypoventilation
- Treat comorbidities: hypertension, diabetes, dyslipidemia, atrial fibrillation
- Avoid sedative-hypnotics and opioids when possible
Second-line / adjunct
- Mandibular advancement devices (MAD) — alternative for mild-moderate OSA or CPAP-intolerant patients
- Upper airway stimulation (hypoglossal nerve stimulator — Inspire) — moderate-severe OSA, BMI <32-35, CPAP-intolerant, with specific anatomic criteria (STAR trial)
- Surgical options: uvulopalatopharyngoplasty (UPPP), tonsillectomy/adenoidectomy (especially pediatric), maxillomandibular advancement, tracheostomy (severe refractory)
- Pharmacotherapy: tirzepatide (SURMOUNT-OSA, FDA-approved 2024 for OSA in obesity) reduces AHI substantially; modafinil/armodafinil for residual sleepiness despite adequate CPAP
- Counsel commercial drivers and aviators on regulatory implications; CPAP adherence requirements
Complications
- Cardiovascular: hypertension (often resistant), atrial fibrillation, stroke, MI, heart failure, sudden cardiac death
- Metabolic: insulin resistance, type 2 diabetes
- Pulmonary hypertension, especially with hypoventilation
- Motor vehicle accidents (sleepiness)
- Cognitive impairment, depression
- Perioperative complications (difficult intubation, sedation sensitivity)
PANCE pearls
- STOP-BANG ≥3 is a high-sensitivity screen; ≥5 has high specificity for moderate-severe OSA.
- Home sleep apnea testing is acceptable for high pretest probability without significant comorbidity but should NOT be used in HF, COPD, neuromuscular disease, or low pretest probability.
- CPAP adherence (>4 h/night on ≥70% of nights) is the metric used by Medicare/insurance for ongoing coverage.
- Tirzepatide (SURMOUNT-OSA, 2024) is the first FDA-approved pharmacotherapy for OSA in obesity — substantial AHI reduction.
- Obesity hypoventilation syndrome (BMI ≥30 + daytime PaCO2 ≥45) often coexists with OSA and is treated primarily with BiPAP/AVAPS rather than CPAP alone.
References
- AASM 2017 — Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea (Kapur et al., J Clin Sleep Med 2017)
- AASM 2019 — Treatment of Adult OSA with Positive Airway Pressure — AASM Clinical Practice Guideline (Patil et al., J Clin Sleep Med 2019)
- STAR Trial — Upper-Airway Stimulation for Obstructive Sleep Apnea (Strollo et al., NEJM 2014)
- SURMOUNT-OSA — Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity (Malhotra et al., NEJM 2024)
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