Type 1 PSG
Standards.
The uncompromised gold standard for sleep architecture analysis. Outlining the minimum acceptable technical specifications for full attended polysomnography.
A Level 1 Polysomnogram (PSG) requires continuous, attended recording in a specialized laboratory setting. It remains the definitive diagnostic tool for complex sleep-disordered breathing, parasomnias, and narcolepsy, distinct from Type II-IV Home Sleep Apnea Tests (HSATs).
1. EEG Montage Requirements (10-20 System)
Accurate sleep staging (N1, N2, N3, REM, Wake) mandates recording of brainwave activity across multiple regions to identify specific waveforms (K-complexes, sleep spindles, slow-wave activity, and alpha rhythm).
The Recommended AASM Montage:
- Frontal (F4-M1, F3-M2): Optimal for capturing maximal slow-wave activity in N3 sleep.
- Central (C4-M1, C3-M2): Essential for defining sleep onset, vertex sharp waves, sleep spindles, and K-complexes.
- Occipital (O2-M1, O1-M2): Necessary for identifying the presence or absence of the alpha rhythm, which characterizes the awake state with eyes closed.
2. Respiratory Monitoring Sensors
To accurately distinguish between obstructive, central, and mixed apneas, as well as hypopneas and RERAs (Respiratory Effort-Related Arousals), a combination of airflow and effort sensors is strictly required.
| Parameter | Primary Sensor | Alternative/Backup |
|---|---|---|
| Apnea Detection (Airflow) | Oronasal Thermal Sensor | Nasal Pressure Transducer |
| Hypopnea Detection | Nasal Pressure Transducer | Oronasal Thermal Sensor (if pressure fails) |
| Respiratory Effort | RIP Belts (Thorax & Abdomen) | Piezoelectric belts (not recommended) |
| Blood Oxygen (SpO2) | Pulse Oximetry (≤ 3s averaging) | Transcutaneous CO2 (for hypoventilation) |
3. Cardiac & Muscular (EMG) Parameters
Determining REM sleep and diagnosing movement disorders requires precise measurement of muscle atonia and phasic activity.
- Submental (Chin) EMG: Requires three electrodes (one center, two lateral). Crucial for documenting the profound muscle atonia that defines REM sleep, or identifying REM Sleep Behavior Disorder (RBD) when atonia is absent.
- Anterior Tibialis EMG: Bilateral placement required to score Periodic Limb Movements of Sleep (PLMS), commonly associated with Restless Legs Syndrome.
- Electrocardiogram (ECG): Modified Lead II standard. Detects arrhythmias common in severe OSA (e.g., bradycardia-tachycardia syndrome).
4. Digital Resolution and Sampling Rates
Software filters and digital sampling must capture high-frequency bursts (like sleep spindles at 11-16 Hz) and slow oscillations without aliasing.