Diagnostic evaluation for obstructive sleep apnea using polysomnography and type III home sleep testing at Sleep Apnea and TMJ Dental Group, West Hills, CA.
Overview of Sleep Apnea Diagnosis
Definitive diagnosis of obstructive sleep apnea requires objective measurement of respiratory events during sleep. Two diagnostic modalities are available: in-laboratory polysomnography (PSG, Type I study) and home sleep apnea testing (HSAT, Type III–IV). Selection depends on pretest clinical probability, presence of comorbidities, and clinical context per AASM clinical practice guidelines.
In-Laboratory Polysomnography (PSG)
Type I PSG is the diagnostic gold standard. It records electroencephalography (EEG), electro-oculography (EOG), electromyography (EMG), electrocardiography (ECG), airflow (thermistor and nasal pressure transducer), respiratory effort (thoracic and abdominal inductance plethysmography), pulse oximetry, and body position. PSG is indicated when:
- HSAT result is negative despite high clinical suspicion
- Significant comorbidities are present: moderate-to-severe COPD, congestive heart failure, neuromuscular disease, suspected central or complex sleep apnea
- Parasomnias or other sleep disorders require evaluation
- PAP titration is performed simultaneously (split-night PSG)
Home Sleep Apnea Testing (HSAT)
Type III HSAT devices record airflow (nasal pressure and thermistor), respiratory effort (chest and abdominal belts), pulse oximetry, and heart rate. They calculate the respiratory event index (REI) rather than AHI (no EEG), which may underestimate true OSA severity due to scoring relative to recording time rather than total sleep time. HSAT is appropriate for adults with high pretest probability of moderate-to-severe OSA without significant comorbidities.
Interpreting Results
Key parameters reported in sleep study results:
- AHI (Apnea-Hypopnea Index): Events per hour of sleep (PSG) or recording time (HSAT). Normal <5; mild 5–14.9; moderate 15–29.9; severe ≥30
- RDI (Respiratory Disturbance Index): Includes RERAs; may identify UARS when AHI is normal or mildly elevated
- ODI (Oxygen Desaturation Index): Frequency of ≥4% SpO2 desaturations per hour
- SpO2 nadir: Lowest oxygen saturation recorded; values <80% indicate severe nocturnal hypoxemia
- Arousal index: Number of arousals per hour; elevated in UARS and correlates with EDS
- Sleep efficiency: Proportion of time in bed spent asleep (PSG only)
Treatment Threshold and Referral
An AHI of ≥15 events/hour, or AHI ≥5 with symptoms (EDS, witnessed apneas, or ≥2 of: gasping/choking, habitual snoring, hypertension, BMI >35, age >50, neck circumference >40 cm, or male sex — STOP-BANG ≥3) establishes the indication for treatment. Oral appliance therapy is indicated as first-line therapy for mild-to-moderate OSA or as an alternative for CPAP-intolerant patients with any severity.
The Consultation Process
At the initial consultation, Dr. Masudian reviews existing sleep study data, performs a clinical and dental examination, evaluates craniofacial anatomy and dental status for OAT candidacy, and coordinates with the supervising sleep physician regarding treatment selection. Patients who have not yet undergone sleep testing are referred to an accredited sleep center or provided with HSAT coordination through the clinic’s collaborative network.
Related Conditions
Patients are seen at the West Hills office from Los Angeles County, Ventura County, West Hills, Canoga Park, Woodland Hills, Calabasas, Sherman Oaks & Encino, Northridge & Chatsworth, Thousand Oaks, Simi Valley, Agoura Hills & Westlake Village.
