314.1 🎓 醫孞生版

314.1.0.1 📌 䞀頁重點

314.1.0.1.1 Obstructive Sleep Apnea (OSA)
314.1.0.1.1.1 Definition
  • Recurrent partial (hypopnea) or complete (apnea) upper airway collapse during sleep
  • ≥ 10 seconds duration
  • ≥ 4% oxygen desaturation OR arousal
314.1.0.1.1.2 Epidemiology
  • 1 in 4 adults worldwide
  • Increasing prevalence (obesity epidemic)
  • Underdiagnosed (80%+ undiagnosed)
  • Men > women (2-3:1); converges post-menopause
314.1.0.1.1.3 Risk Factors
  • Obesity (#1; ↑ AHI per 10 lb)
  • Male sex
  • Age (peaks 50-70s; declines very old)
  • Anatomic: large neck (> 17” men, > 16” women), retrognathia, macroglossia, tonsillar hypertrophy, nasal obstruction
  • Family history
  • Alcohol (relaxes upper airway)
  • Sedatives
  • Smoking
  • Hypothyroidism, acromegaly, Cushing’s
314.1.0.1.1.4 Pathophysiology
  • Pharyngeal collapse during sleep
  • Negative pressure during inspiration → airway closure
  • Activation of pharyngeal dilators normally prevents
  • Sleep ↓ tone → collapse
  • REM sleep ↓ tone more → REM-related events
  • Supine sleep ↑ collapse (positional)
314.1.0.1.1.5 Clinical Features

Symptoms: - Loud snoring - Witnessed apnea - Gasping / choking at night - Excessive daytime sleepiness (EDS) (Epworth ≥ 10) - Morning headache - Memory + concentration issues - Mood changes / depression - Erectile dysfunction - Frequent nocturia

Examination: - Obesity (BMI, neck circumference) - Crowded oropharynx (Mallampati III-IV) - Tonsillar hypertrophy - Retrognathia / micrognathia

314.1.0.1.1.6 Consequences

Cardiovascular: - HTN (especially resistant) - AF (recurrent post-ablation if OSA untreated) - HF (worsens HFrEF + HFpEF) - Stroke - MI - Pulmonary HTN (severe) - Sudden cardiac death

Metabolic: - Insulin resistance + DM - Metabolic syndrome - Dyslipidemia

Neurocognitive: - Daytime sleepiness - Cognitive impairment - Dementia risk - Mood disorders

Other: - Accidents (motor vehicle 2-3x risk) - ↓ Quality of life - Glaucoma - Erectile dysfunction

314.1.0.1.2 Diagnosis
314.1.0.1.2.1 Screening Tools
  • STOP-BANG (Snoring, Tired, Observed apnea, BP, BMI, Age, Neck, Gender)
    • ≥ 3 = high risk; ≥ 5 = very high
  • Epworth Sleepiness Scale: ≥ 10 = excessive daytime sleepiness
  • Berlin Questionnaire
314.1.0.1.2.2 Sleep Studies

Polysomnography (PSG) — Gold Standard: - In-lab overnight study - Multiple channels: - EEG, EOG (sleep staging) - ECG - EMG (chin, leg) - Respiratory effort (chest + abdomen bands) - Airflow (nasal pressure, thermistor) - SpO2 - Body position - Snoring sound - AHI calculation - Distinguishes OSA, CSA, mixed - Identifies REM-related, positional - Periodic limb movements

Home Sleep Apnea Test (HSAT): - Limited channels (respiratory + SpO2 + position) - Convenient, lower cost - For uncomplicated OSA (high pretest probability) - Less sensitive than PSG - Cannot distinguish well from CSA - Not for: HF, neuromuscular, opioid use, severe comorbidity

314.1.0.1.2.3 AHI (Apnea-Hypopnea Index)
  • Events per hour of sleep
  • < 5: normal
  • 5-14: mild OSA
  • 15-29: moderate
  • ≥ 30: severe
314.1.0.1.2.4 Other Indices
  • ODI (Oxygen Desaturation Index): events / hour with ≥ 4% drop
  • RDI (Respiratory Disturbance Index): includes respiratory event-related arousals
  • AI (arousal index): per hour
  • T90: time below SpO2 90%
314.1.0.1.2.5 Diagnostic Criteria (AASM 2014/2017)
  • AHI ≥ 15 OR
  • AHI ≥ 5 + symptoms (sleepiness, snoring, witnessed apnea, mood, etc.) OR comorbidities (HTN, ASCVD, DM, HF, AF, stroke)
314.1.0.1.3 Treatment of OSA
314.1.0.1.3.1 Lifestyle + Conservative
  • Weight loss (5-10% weight loss can ↓ AHI 25-50%)
  • Avoid alcohol + sedatives (especially within 3-4h of bedtime)
  • Positional therapy (avoid supine sleep): pillows, positional alarm
  • Smoking cessation
  • Treat nasal obstruction (decongestants, nasal steroids, septoplasty)
  • Optimize underlying conditions (HF, hypothyroidism, etc.)
314.1.0.1.3.2 CPAP (Continuous Positive Airway Pressure) — Gold Standard

Mechanism: pneumatic splint maintains airway patency

Types: - Standard CPAP (fixed pressure) - Auto-CPAP (APAP): adjusts pressure based on events - BiPAP: different inspiratory + expiratory pressure (CSA, OHS, comfort)

Adherence: - Major challenge; ~ 50% suboptimal use - Goal: ≥ 4 hours / night, ≥ 5 nights / week - Comfort, mask fit, education, follow-up

Outcomes: - Improves daytime sleepiness, BP, QOL, mood, cognition - Reduces AF recurrence post-ablation - HF outcomes mixed

314.1.0.1.3.3 Mandibular Advancement Device (MAD)
  • Custom-fit dental appliance
  • Advances mandible 5-10 mm
  • For mild-moderate OSA
  • Alternative for CPAP-intolerant
  • 50-70% efficacy
  • Dental side effects (jaw, occlusion)
314.1.0.1.3.4 Hypoglossal Nerve Stimulation (HGNS / Inspire)
  • Implanted device stimulates hypoglossal nerve during inspiration → tongue protrusion → airway opens
  • STAR trial (2014, FDA approved)
  • For moderate-severe OSA + CPAP-intolerant + BMI < 32 + no central component + non-circumferential collapse
  • Sleep endoscopy guides patient selection
  • 75% AHI reduction; sustained 5-year
314.1.0.1.3.5 Surgical Options
  • Uvulopalatopharyngoplasty (UPPP): limited efficacy (40-50%)
  • Maxillomandibular advancement (MMA): highly effective for select; large surgery
  • Tracheostomy: rarely (severe + refractory)
  • Bariatric surgery: very effective for obese (BMI > 35)
314.1.0.1.3.6 Pharmacotherapy

Limited Role Historically; New Era: - GLP-1 + tirzepatide (NEW 2024): - SURMOUNT-OSA (2024): tirzepatide reduced AHI by 50%+ in obese patients with OSA - Game-changer - Often combined with CPAP - Acetazolamide: for central sleep apnea, high-altitude - Atomoxetine + oxybutynin: emerging (norepinephrine + anticholinergic — tongue muscle activation)

314.1.0.1.3.7 Other
  • Modafinil / armodafinil for residual sleepiness despite CPAP
  • Solriamfetol (dopamine-norepinephrine reuptake inhibitor): for residual sleepiness
  • Pitolisant (H3 inverse agonist): another option
314.1.0.1.4 Central Sleep Apnea (CSA)
314.1.0.1.4.1 Types

Primary CSA: - Idiopathic - Rare

Cheyne-Stokes Respiration (CSR): - HFrEF (~ 25% of severe) - Brainstem lesion - High altitude - Crescendo-decrescendo pattern

High Altitude Periodic Breathing: - Hypoxia + low CO2 setpoint instability

Opioid-Induced CSA: - Chronic opioid use - Increasing recognition

Treatment-Emergent CSA: - CPAP unmasking - Adapts over time

314.1.0.1.4.2 Treatment

HFrEF + CSR: - Optimize HF therapy - CPAP (CANPAP — neutral) - ASV (adaptive servo-ventilation): caution — SERVE-HF (2015) showed ↑ mortality in HFrEF + CSR (NOT recommended) - O2 supplementation for nocturnal desaturation

Opioid-Induced: - Wean opioid - Naltrexone if appropriate

Primary CSA: - Acetazolamide - O2 - CPAP

314.1.1 Obesity Hypoventilation Syndrome (OHS) — see Ch312

314.1.1.0.0.1 CCHS / Ondine’s Curse
  • PHOX2B mutation
  • Lifelong nocturnal ventilation
  • Diaphragmatic pacing for select
314.1.1.0.0.2 Neuromuscular Disorders
  • ALS, GBS, MG, muscular dystrophy
  • NIV at night → eventually full
  • Diaphragmatic pacing for high cervical SCI
314.1.1.0.1 Sleep + Cardiovascular Disease
314.1.1.0.1.1 OSA + Cardiovascular
  • HTN: 30-50% of OSA patients; resistant HTN common
  • AF: ↑ recurrence post-ablation if OSA untreated (50%+)
  • HF: HFpEF + HFrEF coexistent
  • Stroke: ↑ ischemic + hemorrhagic
  • MI: ↑ nocturnal events
  • Sudden cardiac death
314.1.1.0.1.2 Treatment OSA in CV Disease
  • CPAP improves HTN (modest 2-3 mmHg)
  • AF recurrence reduced
  • HF outcomes unclear
  • Bariatric surgery if obese
314.1.1.0.1.3 SAVE Trial (2016) — CPAP in OSA + CV Disease
  • N = 2717 OSA + established CVD
  • No reduction in CV events
  • Subgroup analyses suggest benefit in compliant users
  • Patient selection + adherence matter
314.1.1.0.2 OSA in Special Populations
314.1.1.0.2.1 Pregnancy
  • ↑ Prevalence with weight gain
  • ↑ Risk for gestational HTN, preeclampsia, GDM
  • CPAP safe + recommended
314.1.1.0.2.2 Pediatric
  • Adenotonsillar hypertrophy most common cause
  • Adenotonsillectomy first-line
  • Daytime symptoms different (ADHD-like, behavioral)
  • BMI association also
314.1.1.0.2.3 Elderly
  • Increasing prevalence with age (then declining very elderly)
  • Diagnosis often delayed
  • CPAP improves cognition, mood
314.1.1.0.2.4 Post-Operative
  • High-risk for complications
  • STOP-BANG screening pre-op
  • CPAP perioperatively if known OSA
  • Avoid opioids if possible

314.1.1.1 🩺 床邊速查

  • AHI ≥ 5 + symptoms = OSA; ≥ 15 = without symptoms
  • OSA severity: mild 5-15, moderate 15-30, severe > 30
  • CPAP: gold standard treatment
  • Inspire HGNS: moderate-severe + CPAP-intolerant + BMI < 32
  • Cheyne-Stokes in HFrEF: NO ASV (SERVE-HF ↑ mortality)
  • SURMOUNT-OSA 2024: tirzepatide reduces AHI 50%+ in obese OSA
  • STOP-BANG ≥ 3: high OSA risk