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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Question 1PulmonaryMedium
A 55-year-old man with obesity (BMI 42 kg/m²) and type 2 diabetes mellitus reports daytime somnolence, morning headaches, and witnessed apneas during sleep. Polysomnography shows an apnea-hypopnea index (AHI) of 38 events/hour. Which of the following is the most important cardiopulmonary complication to screen for in this patient?
ATricuspid regurgitation
BDiastolic dysfunction
CPulmonary hypertension
DHypertrophic cardiomyopathy
Reveal answer & full explanation
Correct answer: C — Pulmonary hypertension
ATricuspid regurgitation
BDiastolic dysfunction
CPulmonary hypertension✓
DHypertrophic cardiomyopathy
Why Pulmonary hypertension is correct
An AHI of 38 events/hour defines severe obstructive sleep apnea (OSA; AHI ≥30)
Chronic nocturnal hypoxemia in severe OSA drives hypoxic pulmonary vasoconstriction and Group 3 pulmonary hypertension (PH)
Echocardiography is the appropriate screening study, and CPAP can reduce PH in these patients
PH is a true cardiopulmonary complication that stays clinically silent until advanced, so screening is worthwhile in severe disease
Why the others are wrong
Tricuspid regurgitation — TR is usually a downstream consequence of OSA-related PH rather than the primary entity to screen for, and shows up on the same echo as a sign of elevated right-heart pressures (buzzword-matching 'right heart' without naming the underlying process)
Diastolic dysfunction — OSA is associated with diastolic dysfunction, but it is a left-heart process and not the classic cardiopulmonary complication of severe OSA (premature closure on a real but secondary association)
Hypertrophic cardiomyopathy — HCM is a genetic sarcomeric disorder unrelated to OSA; severe OSA does not cause it (confused-with-X: hypertensive LV hypertrophy is not HCM)
Question 2PulmonaryEasy
A 45-year-old obese male (BMI 38) has excessive daytime sleepiness, morning headaches, and his partner reports apneas during sleep. His Epworth Sleepiness Scale score is 16. Polysomnography shows apnea-hypopnea index (AHI) of 28 with O2 nadir of 82%. Which of the following is the first-line treatment?
AUvulopalatopharyngoplasty
BMandibular advancement device
CWeight loss counseling
DCPAP
Reveal answer & full explanation
Correct answer: D — CPAP
AUvulopalatopharyngoplasty
BMandibular advancement device
CWeight loss counseling
DCPAP✓
Why CPAP is correct
This patient has moderate obstructive sleep apnea (OSA): apnea-hypopnea index (AHI) of 28 (moderate = 15–30 events/hour), O2 nadir of 82%, and Epworth Sleepiness Scale score of 16.
Continuous positive airway pressure (CPAP) is the first-line treatment for all moderate-to-severe OSA — it reduces AHI, improves daytime sleepiness, and reduces cardiovascular (CV) risk.
Why the others are wrong
C) Weight loss counseling — 10% body weight loss reduces AHI by approximately 26% (Sleep AHEAD trial) and is recommended adjunctively, but is not first-line monotherapy for moderate OSA.
B) Mandibular advancement device — an alternative to CPAP for mild-to-moderate OSA or CPAP-intolerant patients; not first-line when CPAP is appropriate.
A) Uvulopalatopharyngoplasty (UPPP) — indicated for anatomic obstruction; adjunct to CPAP, not a first-line standalone treatment.
Additional high-yield points
OSA severity by AHI: mild 5–14, moderate 15–30, severe above 30 events/hour.
Hypoglossal nerve stimulator (Inspire): indicated for moderate-to-severe OSA (AHI 15–65) with CPAP failure and low BMI (below 32).
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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
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
AHI severity stratification and management approach for OSA (AASM 2014).
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
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
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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