NBRC SDS flashcards
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- Polysomnography EEG derivations
- Standard PSG uses frontal (F4-M1), central (C4-M1), and occipital (O2-M1) derivations so slow waves, sleep spindles, and alpha rhythm can be distinguished across regions.
- Obstructive apnea definition
- A ≥90% airflow reduction lasting at least 10 seconds with continued or increased inspiratory effort, reflecting upper airway collapse against an actively breathing chest and abdomen.
- Central apnea definition
- A ≥90% airflow reduction lasting at least 10 seconds with absent inspiratory effort on effort belts, indicating loss of respiratory drive rather than airway obstruction.
- Mixed apnea definition
- An apnea that starts with no respiratory effort (central component) and ends with resumption of effort against a closed airway (obstructive component) within the same event.
- Hypopnea scoring criteria
- Recommended rule: ≥30% airflow drop for ≥10 seconds with ≥3% desaturation or an arousal. Acceptable rule: ≥30% drop with ≥4% desaturation only.
- AHI severity thresholds
- Apnea-hypopnea index of 5-14.9 events/hour is mild, 15-29.9 is moderate, and 30 or more is severe obstructive sleep apnea in adults.
- Oxygen desaturation index
- ODI counts desaturations of a chosen depth (3% or 4%) per hour of sleep. It approximates but does not equal AHI because arousals without desaturation are excluded.
- N1 sleep features
- Stage N1 shows low-amplitude mixed-frequency EEG with more than 50% theta activity, slow rolling eye movements, and attenuated but present chin EMG tone.
- N2 sleep features
- Stage N2 is scored when K-complexes or sleep spindles appear on a low-amplitude mixed-frequency background, without enough slow-wave activity to meet N3 criteria.
- N3 sleep features
- Stage N3 requires at least 20% of the epoch occupied by slow waves at 0.5-2 Hz and over 75 microvolts peak-to-peak amplitude, usually in frontal leads.
- REM sleep features
- REM shows low-voltage mixed-frequency EEG, episodic rapid eye movements, and the lowest chin EMG tone of the night, often with sawtooth waves and irregular breathing.
- Arousal scoring rule
- An arousal is an abrupt EEG frequency shift to alpha, theta, or above 16 Hz lasting at least 3 seconds, counted only after 10 seconds of stable sleep.
- Sleep efficiency formula
- Sleep efficiency equals total sleep time divided by total recording (or time-in-bed) time, multiplied by 100. Values below 85% suggest poor sleep continuity.
- Sleep latency definition
- Sleep latency is the time from lights out to the first epoch of any sleep stage, normally under 30 minutes in adults and shorter in children.
- CPAP titration starting point
- Begin CPAP titration at 4-5 cmH2O and increase by 1-2 cmH2O increments until apneas, hypopneas, flow limitation, and snoring are eliminated in all sleep positions and stages.
- Bilevel pressure titration logic
- Set EPAP high enough to eliminate obstructive events, then set IPAP-EPAP pressure support to correct hypoventilation and flow limitation, typically 4-10 cmH2O of support.
- Split-night study criteria
- A split-night PSG converts from diagnosis to titration when AHI is at least 40 in the first 2 hours, or 20-40 with clinical judgment, allowing same-night pressure titration.
- Flow limitation detection
- Flow limitation appears as flattened or rounded inspiratory nasal pressure contours without meeting hypopnea criteria, signaling elevated upper airway resistance that often precedes arousal.
- Positional sleep apnea
- Positional OSA is present when supine AHI is at least twice the non-supine AHI, supporting positional therapy or adjustment of pressure needs by body position.
- Cheyne-Stokes respiration
- Cheyne-Stokes respiration is a cyclic crescendo-decrescendo breathing pattern with central apneas or hypopneas, commonly seen in heart failure and associated with delayed circulation time.
- Treatment-emergent central apnea
- Treatment-emergent central apnea is the appearance or persistence of central events during PAP titration or early therapy, often resolving with time or requiring adaptive servo-ventilation.
- Adaptive servo-ventilation
- ASV delivers servo-controlled pressure support that varies breath to breath to stabilize ventilation, targeting central sleep apnea and periodic breathing patterns.
- BiPAP ST mode
- Spontaneous/timed bilevel ventilation provides a set backup rate so a mandatory breath is delivered when the patient's spontaneous effort falls below the set interval.
- Average volume assured pressure support
- AVAPS adjusts inspiratory pressure automatically to maintain a target tidal volume, useful for obesity hypoventilation and neuromuscular hypoventilation syndromes.
- MSLT narcolepsy criterion
- A mean sleep latency of 8 minutes or less with two or more sleep-onset REM periods on the multiple sleep latency test supports a narcolepsy diagnosis.
- Maintenance of wakefulness test
- The MWT measures the ability to stay awake in a quiet setting across four 40-minute trials, used to assess treatment response and fitness for safety-sensitive duties.
- Home sleep apnea test limits
- HSAT typically records airflow, effort, oximetry, and position without EEG, so it underestimates AHI because sleep time and arousals cannot be scored.
- PAP adherence threshold
- Medicare and most insurers require CPAP use of at least 4 hours per night on 70% of nights during a 30-day period for continued coverage.
- Obesity hypoventilation syndrome
- OHS is defined by body mass index ≥30, daytime PaCO2 ≥45 mmHg, and sleep-disordered breathing after other causes of hypoventilation are excluded.
- Residual AHI on therapy
- Residual AHI is the event rate remaining on PAP, obtained from device download or titration data; values above 5 events/hour warrant review of mask fit, leaks, and pressure.
- Mask leak assessment
- Clinically significant leak is often defined as greater than 24 L/min on device download; large leaks reduce pressure delivery and cause arousals, dry mouth, and eye irritation.
- Oximetry desaturation nadir
- The nadir SpO2 is the lowest oxygen saturation recorded during the study; values below 88% for 5 minutes or more meet criteria for nocturnal hypoxemia in many payer policies.
- Sleep stage REM latency
- REM latency is the time from sleep onset to the first REM epoch; values under 15 minutes suggest REM pressure and support narcolepsy or sleep deprivation evaluation.