RST flashcards
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- Sleep stage N1
- Transitional stage with low-amplitude mixed-frequency EEG, slow eye movements, and attenuation of alpha; vertex sharp waves may appear. No spindles or K-complexes.
- K-complex definition
- A negative sharp wave immediately followed by a positive component standing out from background EEG, duration >=0.5 seconds, maximal over frontal regions.
- Sleep spindle
- A train of distinct 11-16 Hz waves (most commonly 12-14 Hz) lasting >=0.5 seconds, maximal over central derivations, marking stage N2.
- Slow wave criterion
- EEG waves of 0.5-2 Hz with peak-to-peak amplitude >75 µV, measured over frontal derivations; >20% of an epoch scores N3.
- Epoch length
- Standard polysomnography scoring divides the recording into 30-second epochs; each epoch receives a single sleep stage by majority rule.
- REM sleep criteria
- Low-amplitude mixed-frequency EEG, low chin EMG tone, and rapid eye movements; requires all three features to score REM.
- 10-20 system
- Standardized scalp electrode placement using measured distances between nasion and inion and between preauricular points; defines F, C, O, and other sites.
- EOG placement
- Electrodes placed near outer canthi to detect conjugate eye movements; left eye referenced to right mastoid and right eye to left mastoid.
- Chin EMG purpose
- Submental EMG records muscle tone used to distinguish wake, NREM, and REM; lowest tone occurs in REM sleep.
- Impedance target
- Electrode-skin impedance should be kept below about 5 kOhm to reduce artifact and signal loss on EEG, EOG, and EMG channels.
- Oximetry averaging
- Pulse oximeter SpO2 values are averaged over 3 seconds for scoring; desaturation is a fall from baseline meeting the chosen threshold.
- Sleep onset latency
- Time from lights out to the first epoch scored as any sleep stage; a standard measure of sleep initiation difficulty.
- REM latency
- Interval from sleep onset to the first epoch of REM sleep; normally about 90-120 minutes in adults.
- Apnea definition
- A >=90% reduction in airflow lasting >=10 seconds; scored as obstructive, central, or mixed based on respiratory effort.
- Hypopnea definition
- A >=30% airflow reduction for >=10 seconds with >=3% desaturation or an arousal under the AASM recommended rule.
- AHI formula
- Apnea-Hypopnea Index equals total apneas plus hypopneas divided by total sleep time in hours; used to grade OSA severity.
- OSA severity thresholds
- AHI 5-15 is mild, 15-30 is moderate, and greater than 30 events per hour is severe obstructive sleep apnea.
- Oxygen desaturation index
- Number of desaturation events per hour of sleep; correlates with AHI but does not replace AHI for diagnosis.
- Epworth Sleepiness Scale
- Eight-item self-report scored 0-24 measuring likelihood of dozing in daily situations; scores above 10 suggest abnormal sleepiness.
- STOP-BANG screen
- Eight-item OSA risk screen: snoring, tiredness, observed apnea, pressure, BMI, age, neck circumference, gender; >=3 positives indicates risk.
- CPAP adherence rule
- Commonly defined as >=4 hours of use per night on >=70% of nights, typically assessed over a 30-day period.
- Insomnia disorder criteria
- Difficulty initiating or maintaining sleep, or early awakening, >=3 nights weekly for >=3 months with associated daytime impairment.
- Narcolepsy type 1
- Characterized by cataplexy and low CSF hypocretin-1; MSLT shows mean sleep latency <=8 minutes with >=2 SOREMPs.
- Restless legs syndrome
- Urge to move legs, worse at rest and evening, relieved by movement; clinical diagnosis requiring symptoms >=3 times weekly.
- MSLT purpose
- Multiple Sleep Latency Test: four to five nap opportunities after overnight PSG measuring sleep latency and SOREMPs to evaluate central hypersomnia.
- SOREMP definition
- Sleep-onset REM period: a nap with REM latency <=15 minutes on MSLT, or <=15 minutes from sleep onset on prior PSG.
- Central sleep apnea
- Apnea events with absent airflow and absent respiratory effort; often seen in heart failure or with opioid use.
- Periodic limb movements
- Repetitive limb movements lasting 0.5-10 seconds, occurring 5-90 seconds apart, scored from anterior tibialis EMG during sleep.
- Bilevel PAP role
- Noninvasive ventilation delivering separate inspiratory and expiratory pressures; used for OSA with hypoventilation or PAP intolerance.
- Oral appliance therapy
- Mandibular advancement device that repositions the jaw to enlarge the upper airway; an option for mild to moderate OSA.
- Sleep hygiene components
- Behavioral practices including consistent sleep schedule, limiting caffeine and alcohol, and reducing light and noise before bed.
- CBT-I core components
- Cognitive behavioral therapy for insomnia includes stimulus control, sleep restriction, cognitive restructuring, and relaxation training.