What is the diagnosis for this patient’s suspected sleep‑related breathing disorder?

Diagnosis of Obstructive Sleep Apnea

The diagnosis of obstructive sleep apnea (OSA) is established by polysomnography demonstrating an Apnea-Hypopnea Index (AHI) ≥5 events per hour with accompanying symptoms (snoring, witnessed apneas, daytime sleepiness, gasping), or an AHI ≥15 events per hour regardless of symptoms. 1

Diagnostic Criteria

Primary diagnostic thresholds are:

• AHI ≥5/hour WITH symptoms = OSA diagnosis 2, 1
• AHI ≥15/hour WITHOUT symptoms = OSA diagnosis 1

The AHI calculation divides total apneas plus hypopneas by total sleep time in hours. 1

Hypopnea Scoring Requirements

A hypopnea event must meet ALL three criteria: 1

• Peak airflow drops ≥30% from baseline
• Duration of the ≥30% drop is ≥10 seconds
• Either ≥3% oxygen desaturation from baseline OR an EEG-documented arousal occurs

Critical caveat: The Centers for Medicare and Medicaid Services uses a ≥4% desaturation threshold, which underdiagnoses OSA in symptomatic patients. The American Academy of Sleep Medicine strongly recommends the 3% desaturation or arousal-based criteria. 1

Alternative Diagnostic Index

The Respiratory Disturbance Index (RDI) provides more comprehensive assessment by including respiratory effort-related arousals (RERAs): 1

• RDI = (# apneas + # hypopneas + # RERAs) × 60 / total sleep time in minutes
• RDI ≥5 events/hour is diagnostic for OSA 1

Required Diagnostic Testing

Polysomnography (PSG) is the gold standard and must include: 1, 3

• EEG for sleep staging and arousal detection
• EOG (electrooculography)
• Chin EMG
• Airflow measurement
• Oxygen saturation monitoring
• Respiratory effort monitoring
• ECG 1

Home sleep apnea testing (Type III) may be used ONLY when: 1

• High pretest probability of moderate-to-severe OSA exists
• Manually scored respiratory event index ≥15 events/hour establishes diagnosis
• Negative HSAT requires confirmatory in-laboratory PSG due to inability to detect arousal-based events 1

Clinical Assessment Priorities

Obtain detailed history focusing on: 1, 4

• Snoring characteristics and witnessed apneas
• Gasping or choking at night
• Daytime sleepiness (though 78% of confirmed OSA patients deny snoring and sleepiness) 1
• Nocturia and unrefreshing sleep 1, 4
• Sleep quality complaints and frequent awakenings 4

Physical examination must document: 4

• Neck circumference (≥17 inches in men, ≥16 inches in women indicates increased risk) 1, 4
• Modified Mallampati score 4
• Tonsillar hypertrophy and soft palate redundancy 4

Critical Diagnostic Pitfalls

Do not rely on symptoms alone - clinical symptoms cannot predict disease severity or exclude diagnosis, and patients with severe OSA (AHI ≥30) often report normal sleepiness scores. 1 Objective sleep testing is mandatory. 1, 3

Do not use oximetry alone - pulse oximetry is insufficient to assess for sleep-disordered breathing and cannot screen adequately for OSA. 2, 5

Do not continue empiric therapy without objective confirmation - this delays identification of alternative treatable causes and may worsen outcomes. 3

Differential Diagnosis Considerations

When OSA is suspected but testing is negative or symptoms persist despite treatment, evaluate for: 3

• Central sleep apnea or treatment-emergent central sleep apnea 3
• Narcolepsy (requires PSG followed by multiple sleep latency testing) 3
• Idiopathic hypersomnia 3
• Restless legs syndrome and periodic limb movement disorder 3
• Sleep deprivation, hypothyroidism, depression, sedating medications 4, 3
• Central hypoventilation syndromes in patients with cardiopulmonary disease, neuromuscular conditions, chronic opioid use, or stroke 3