6.1 High-Yield Recap by Domain
Key Takeaways
- An apnea is a >=90% airflow drop for >=10 seconds; a recommended-rule hypopnea is a >=30% airflow drop for >=10 seconds with either >=3% desaturation or an arousal
- AHI = (apneas + hypopneas) / total sleep time in hours; PLMI = periodic limb movements per hour of sleep, clinically significant at >=15/hour in adults
- Stage N3 requires slow-wave activity (0.5-2 Hz, >75 microvolts) over >=20% of the epoch; REM shows low-amplitude mixed-frequency EEG, the lowest chin EMG of the night, and rapid eye movements
- Apnea classification is decided by respiratory effort: absent effort = central, continued/increased effort = obstructive, absent-then-resumed = mixed
- EEG and EOG electrode impedances should be kept at or below 5 kilo-ohms and balanced between paired electrodes to reject common-mode noise
6.1 High-Yield Recap by Domain
Quick Answer: The Registered Polysomnographic Technologist (RPSGT) exam has 175 multiple-choice items across four Board of Registered Polysomnographic Technologists (BRPT) content domains (blueprint effective September 1, 2023). This recap condenses the facts that recur most often: scoring cutoffs, event definitions, the Apnea-Hypopnea Index (AHI), Respiratory Disturbance Index (RDI), and Periodic Limb Movement Index (PLMI) calculations, positive airway pressure (PAP) titration logic, and montage and impedance standards.
This is a fast-pass review, not a re-teaching. Read each fact, confirm you can explain why it is true, and flag anything that does not click for a final-week deep dive. The exam rewards integration: one vignette can blend setup, scoring, and intervention, so memorizing isolated numbers is not enough.
Domain-to-Facts Map
| BRPT Domain (Weight) | Must-Know Facts |
|---|---|
| Clinical Overview, Education & Patient Support (20.0%) | Pre-study patient assessment, medication and caffeine history, fall-risk and seizure precautions; basic life support (BLS)/CPR current at testing; informed consent; scope-of-practice limits; lights-out documentation. |
| Sleep Study Preparation & Performance (27.3%) | International 10-20 electrode placement; EEG impedances <= 5 kilo-ohms and balanced; biocalibrations before lights out; derivations F4-M1, C4-M1, O2-M1; sampling/filter settings; artifact recognition (60 Hz, sweat, ECG, movement). |
| Scoring, Reporting & Data Verification (25.3%) | Stage N1/N2/N3/R rules; apnea vs hypopnea; obstructive vs central vs mixed; arousal (>=3 second EEG shift); AHI, RDI, PLMI; report QA against raw data. |
| Treatment & Intervention (27.3%) | CPAP, bilevel positive airway pressure (BiPAP), and auto-titrating logic; split-night criteria; supplemental oxygen titration; mask fit and leak troubleshooting; when to alert the physician. |
Note the math: the three technical domains (27.3% + 25.3% + 27.3%) supply roughly 80% of scored content, so any weakness there is high-risk.
Sleep Staging Cutoffs
- Stage W: alpha rhythm over the occipital region with eyes closed, or eye blinks, reading eye movements, and high chin tone when eyes are open.
- Stage N1: low-amplitude mixed-frequency EEG, slow rolling eye movements, and possible vertex sharp waves.
- Stage N2: K-complexes and/or sleep spindles. An epoch scores N2 if it contains a K-complex unassociated with an arousal or a sleep spindle in the first half of the epoch or the last half of the prior epoch.
- Stage N3: slow-wave activity (0.5-2 Hz, >75 microvolts) for >= 20% of the epoch.
- Stage R (REM): low-amplitude mixed-frequency EEG, the lowest chin electromyogram (EMG) of the recording, and rapid eye movements; sawtooth waves support REM.
Respiratory Event Definitions
| Event | Core Criteria |
|---|---|
| Apnea | Airflow drop >= 90% of baseline for >= 10 seconds. |
| Obstructive apnea | Apnea criteria with continued or increased respiratory effort. |
| Central apnea | Apnea criteria with absent respiratory effort throughout. |
| Mixed apnea | Absent effort early, then resumed effort before airflow returns. |
| Hypopnea (recommended) | Airflow drop >= 30% for >= 10 seconds with >= 3% desaturation OR an arousal. |
| RERA | Respiratory-effort-related arousal: increasing effort or flow limitation for >= 10 seconds leading to an arousal, not meeting apnea or hypopnea criteria. |
Index Math You Must Be Able to Do
- AHI = (total apneas + total hypopneas) / total sleep time in hours.
- RDI = (apneas + hypopneas + RERAs) / total sleep time in hours.
- PLMI = total periodic limb movements / total sleep time in hours; >= 15/hour is generally clinically significant in adults.
- Worked example: 60 apneas + 30 hypopneas over 6.0 hours = 90 / 6 = AHI 15 (moderate range).
- Adult severity bands: AHI 5-14.9 mild, 15-29.9 moderate, >= 30 severe.
PAP Titration & Montage Standards
- Start CPAP at a low pressure (commonly 4-5 cm H2O) and increase in small steps to eliminate, in order: obstructive apneas, hypopneas, RERAs, and snoring, then residual flow limitation.
- Confirm the optimal pressure holds in supine REM sleep, the most collapsible state; move to bilevel for pressure intolerance or persistent events at high CPAP.
- Split-night protocols typically require AHI >= 40 in the first 2 hours (or >= 20 with clinical judgment) to convert to titration the same night.
- Place EEG electrodes per the International 10-20 System; keep EEG and electrooculogram (EOG) impedances <= 5 kilo-ohms and balanced; run biocalibrations (eyes, blink, grit teeth, breathe, hold breath, flex foot) before lights out; correct artifact sources rather than only filtering.
Recommended Recording Parameters
The exam expects you to know AASM-recommended digital settings cold, because acquisition (27.3%) is a top-weighted domain. Memorize the sampling rates and filters as a package:
| Channel | Low-Freq Filter | High-Freq Filter | Sampling (desirable) |
|---|---|---|---|
| EEG, EOG, EMG | 0.3 Hz (EEG/EOG), 10 Hz (EMG) | 35 Hz (EEG/EOG), 100 Hz (EMG) | 500 Hz |
| ECG | 0.3 Hz | 70 Hz | 500 Hz |
| Airflow (thermal/nasal pressure) | 0.1 Hz | 15 Hz | 100 Hz |
| Oximetry (SpO2) | --- | --- | 25 Hz (max averaging 3 s) |
Worked scenario: a vignette shows EEG that looks "blunted" with no spindles visible. Before assuming a staging problem, confirm the high-frequency filter has not been set too low (for example 15 Hz instead of 35 Hz), which attenuates spindle and beta activity. The fix is a parameter correction, not a re-prep.
Pediatric vs Adult Rule Differences (Common Trap)
The exam frequently contrasts pediatric and adult criteria. Do not apply adult numbers to a child:
- Pediatric apnea uses a duration of >= 2 missed breaths (often shorter than 10 seconds), not a flat 10-second floor.
- Pediatric hypopnea uses >= 30% airflow reduction with >= 3% desaturation or an arousal, similar in shape to the adult recommended rule but scored against the child's respiratory rate.
- Pediatric obstructive AHI >= 1/hour is already abnormal, versus the adult threshold of 5/hour for mild disease.
If a stem gives the patient's age as 6 years, the decisive variable may be which rule set applies, not the raw numbers.
A study shows 48 obstructive apneas and 42 hypopneas over 5.0 hours of total sleep time, with periodic limb movements counted at 35 over the same period. Which interpretation is correct?
During REM sleep an obstructive apnea is identified. Which combination of findings is most consistent with both the REM stage and the obstructive classification?
A technologist begins CPAP titration. Which sequence best reflects standard titration priorities?
EEG channels show a consistent 60 Hz artifact on several derivations. What is the most appropriate first response?