Polysomnography and Home Sleep Testing
Expert-defined terms from the Professional Certificate in Sleep Medicine for Dentists course at London School of Planning and Management. Free to read, free to share, paired with a professional course.
Apnea #
Hypopnea Index (AHI) – a numeric value representing the total number of apneas and hypopneas per hour of sleep. Related terms: obstructive sleep apnea, central sleep apnea. Example: An AHI of 15 indicates moderate OSA. Practical application: Guides treatment intensity; higher AHI often leads to CPAP prescription. Challenges: Night‑to‑night variability may misclassify severity.
Apnea – a complete cessation of airflow lasting at least 10 seconds #
Related terms: obstructive apnea, central apnea. Example: A 12‑second pause during REM sleep. Practical application: Identified on polysomnography (PSG) via nasal pressure and thoracoabdominal belts. Challenges: Differentiating obstructive from central events without esophageal pressure monitoring.
Apnea‑Positive Airway Pressure (APAP) – an auto‑adjusting CPAP device tha… #
Related terms: CPAP, bi‑level PAP. Example: APAP delivers 8 cm H₂O at rest and rises to 12 cm H₂O during an apnea. Practical application: Often used in home sleep testing (HST) as a trial device. Challenges: May undershoot pressure in severe OSA, leading to residual events.
Arterial Blood Gas (ABG) – laboratory test measuring oxygen, carbon dioxi… #
Related terms: overnight oximetry, hypoxemia. Example: An ABG showing PaO₂ = 55 mmHg during sleep. Practical application: Confirms nocturnal hypoxemia when PSG shows desaturation. Challenges: Invasive; not routinely performed in HST.
Auto‑Scoring Algorithms – software routines that automatically identify s… #
Related terms: manual scoring, epoch. Example: An algorithm classifies 30‑second epochs as N2 sleep. Practical application: Reduces technician workload in busy sleep labs. Challenges: Accuracy may decline with atypical waveforms or high movement artifact.
Bi‑Level Positive Airway Pressure (BiPAP) – a device delivering separate… #
Related terms: APAP, CPAP. Example: IPAP = 15 cm H₂O, EPAP = 8 cm H₂O for a patient with co‑existing COPD. Practical application: Used when CPAP intolerance is due to high EPAP. Challenges: More complex titration; higher cost.
Body Position Sensor – a device, often an accelerometer, that records the… #
Related terms: positional OSA, supine‑predominant apnea. Example: Sensor detects a shift from supine to lateral position, reducing AHI. Practical application: Guides positional therapy recommendations. Challenges: Sensor displacement can produce false‑positive positional data.
Central Sleep Apnea (CSA) – cessation of airflow without respiratory effo… #
Related terms: obstructive sleep apnea, Cheyne‑Stokes respiration. Example: PSG shows flat thoracoabdominal traces during a 20‑second pause. Practical application: Requires different treatment (e.G., Adaptive servo‑ventilation). Challenges: Distinguishing CSA from mixed events in limited‑channel HST.
Cheyne‑Stokes Respiration – a pattern of cyclic crescendo‑decrescendo bre… #
Related terms: CSA, heart failure. Example: Observed in a patient with left ventricular dysfunction during PSG. Practical application: Signals underlying cardiac disease; may influence PAP settings. Challenges: May be missed on HST lacking CO₂ monitoring.
Clinician‑Directed Home Sleep Testing (HST) – a protocol where the sleep… #
Related terms: direct‑to‑consumer HST, lab‑based PSG. Example: A dentist orders an HST for a patient with snoring and mild hypertension. Practical application: Increases access for dental sleep clinics. Challenges: Requires training to avoid misinterpretation of artifacts.
CO₂ Monitoring – measurement of end‑tidal or transcutaneous carbon dioxid… #
Related terms: capnography, hypoventilation. Example: Elevated ETCO₂ during REM sleep suggests hypoventilation. Practical application: Detects hypoventilation syndromes not captured by oximetry alone. Challenges: Limited availability in HST devices; sensor drift.
Continuous Positive Airway Pressure (CPAP) – a therapy delivering constan… #
Related terms: APAP, BiPAP. Example: 10 Cm H₂O pressure reduces AHI from 30 to 2. Practical application: First‑line treatment for OSA; can be prescribed after successful HST. Challenges: Patient adherence, mask leaks, and pressure intolerance.
Desaturation Index (ODI) – number of oxygen desaturation events per hour,… #
Related terms: AHI, pulse oximetry. Example: ODI = 12 events/h correlates with mild OSA. Practical application: Used when full PSG is unavailable; guides referral decisions. Challenges: May underestimate severity in patients with baseline low SpO₂.
Diagnostic Sensitivity – the ability of a test to correctly identify thos… #
Related terms: specificity, false‑negative. Example: PSG sensitivity for OSA > 95 %; HST sensitivity ~ 85 % for moderate‑to‑severe OSA. Practical application: Influences choice of test based on pre‑test probability. Challenges: Lower sensitivity in mild OSA or comorbid insomnia.
Diagnostic Specificity – the ability of a test to correctly identify thos… #
Related terms: sensitivity, false‑positive. Example: HST specificity for moderate OSA may exceed 90 %. Practical application: High specificity reduces unnecessary treatment. Challenges: Over‑reliance may miss atypical presentations.
Diagnostic Threshold – the AHI or ODI value at which a diagnosis is consi… #
Related terms: AHI cut‑offs, clinical significance. Example: AHI ≥ 5 events/h is the standard threshold for OSA. Practical application: Guides reporting on HST results. Challenges: Thresholds may not reflect symptom burden; individualized assessment needed.
Digital Signal Processing (DSP) – techniques used to filter, amplify, and… #
Related terms: band‑pass filter, artifact reduction. Example: DSP removes power‑line noise from EEG. Practical application: Improves accuracy of automated scoring. Challenges: Over‑filtering can distort true events.
Electroencephalogram (EEG) – recording of cortical electrical activity us… #
Related terms: sleep architecture, alpha rhythm. Example: N2 stage identified by sleep spindles on EEG. Practical application: Essential for full PSG; omitted in most HST devices. Challenges: Electrode placement errors produce artifact.
Electrooculogram (EOG) – measurement of eye movements to differentiate RE… #
Related terms: REM sleep, sleep staging. Example: Rapid eye movements on EOG accompany low‑amplitude EEG. Practical application: Helps identify REM‑related apnea patterns. Challenges: Not captured in limited‑channel HST.
Electromyogram (EMG) – recording of muscle activity, commonly from chin (… #
Related terms: arousal, sleep fragmentation. Example: Increased chin EMG amplitude signals micro‑arousal. Practical application: Arousal scoring improves event classification. Challenges: Surface EMG may pick up movement artifact.
Epworth Sleepiness Scale (ESS) – a self‑administered questionnaire assess… #
Related terms: subjective sleepiness, clinical screening. Example: ESS score of 12 suggests moderate sleepiness. Practical application: Used in dental sleep clinics to prioritize patients for testing. Challenges: Subjectivity; cultural differences affect scoring.
False‑Positive Result – a test indicating disease when none exists #
Related terms: specificity, over‑diagnosis. Example: HST reports AHI = 7 in a patient without OSA. Practical application: May lead to unnecessary CPAP prescription. Challenges: Reducing false positives while maintaining sensitivity.
False‑Negative Result – a test failing to detect disease that is present #
Related terms: sensitivity, under‑diagnosis. Example: PSG missed a mild OSA case due to technical failure. Practical application: Necessitates repeat testing or alternative diagnostics. Challenges: Particularly common in HST for patients with comorbid insomnia.
Frequency‑Domain Analysis – evaluating signals based on their spectral co… #
Related terms: FFT, power spectrum. Example: Identifying delta activity during deep sleep via Fourier transform. Practical application: Enhances automated sleep stage classification. Challenges: Requires high‑quality data; noise can distort spectra.
Full‑Night Polysomnography (PSG) – comprehensive sleep study recording EE… #
Related terms: lab‑based sleep study, gold‑standard. Example: Overnight PSG reveals AHI = 28 with REM predominance. Practical application: Definitive diagnostic tool for complex cases. Challenges: Cost, limited availability, patient inconvenience.
Hypopnea – a partial reduction in airflow (≥30 % drop) lasting ≥10 second… #
Related terms: apnea, AHI. Example: A 12‑second hypopnea causing a 4 % SpO₂ drop. Practical application: Counts toward AHI; influences treatment decisions. Challenges: Varying scoring criteria across societies.
Hypoxemia – low arterial oxygen saturation, often defined as SpO₂ < 90 %… #
Related terms: desaturation index, oxygen therapy. Example: SpO₂ nadir of 82 % during REM. Practical application: Guides urgency of intervention. Challenges: Intermittent desaturations may be missed on spot checks.
Integrated Sleep Monitoring (ISM) – a hybrid approach combining limited‑c… #
Related terms: simplified PSG, home‑based monitoring. Example: Device records airflow, oximetry, and frontal EEG. Practical application: Improves HST accuracy for patients with borderline OSA. Challenges: Increased cost and setup complexity.
Insomnia – difficulty initiating or maintaining sleep, often co‑existing… #
Related terms: sleep fragmentation, comorbid sleep disorder. Example: Patient reports 30‑minute sleep latency despite high AHI. Practical application: Requires combined treatment strategies. Challenges: Differentiating primary insomnia from OSA‑related sleep disruption.
International Classification of Sleep Disorders (ICSD) – authoritative ta… #
Related terms: diagnostic criteria, ICD‑10. Example: ICSD‑3 defines OSA severity by AHI thresholds. Practical application: Provides standardized language for dental sleep medicine documentation. Challenges: Updates may lag behind emerging research.
Latency to Sleep Onset (LSO) – time from lights‑out to the first epoch of… #
Related terms: sleep efficiency, insomnia. Example: LSO of 25 minutes on PSG. Practical application: Helps assess sleep quality in HST when device records sleep/wake. Challenges: Accurate detection requires EEG.
Mandibular Advancement Device (MAD) – an oral appliance that protrudes th… #
Related terms: oral appliance therapy, positional therapy. Example: Custom MAD reduces AHI from 22 to 8. Practical application: First‑line for mild‑to‑moderate OSA in dental settings. Challenges: Requires titration; may cause TMJ discomfort.
Mixed Apnea – an event that begins as central (no effort) and ends as obs… #
Related terms: central apnea, obstructive apnea. Example: 15‑Second mixed apnea with initial flat thoracoabdominal trace followed by effort. Practical application: Influences choice of adaptive servo‑ventilation. Challenges: Identification may be limited on HST lacking effort belts.
Movement Artifact – extraneous signal caused by patient motion, contamina… #
Related terms: signal noise, quality control. Example: Sudden spikes on airflow sensor due to turning. Practical application: Requires data cleaning before scoring. Challenges: High artifact rates reduce diagnostic yield of HST.
Night‑to‑Night Variability – fluctuations in sleep parameters across diff… #
Related terms: repeat testing, reliability. Example: AHI of 22 on night 1, 14 on night 2. Practical application: May necessitate two‑night HST for borderline cases. Challenges: Increases cost and patient burden.
Obstructive Sleep Apnea (OSA) – repeated upper airway collapse during sle… #
Related terms: apnea, hypopnea. Example: PSG shows AHI = 30 with predominantly supine events. Practical application: Primary target of dental sleep medicine; treatment may include MAD, CPAP, or surgery. Challenges: Under‑diagnosis in asymptomatic patients.
Oximetry‑Only Screening – using pulse oximetry alone to detect desaturati… #
Related terms: ODI, screening tool. Example: Overnight SpO₂ trace shows ≥5 % desaturation episodes. Practical application: Low‑cost preliminary assessment in dental clinics. Challenges: Low sensitivity for mild OSA; unable to differentiate central vs obstructive events.
Positional Therapy – interventions that encourage sleeping in non‑supine… #
Related terms: positional OSA, sleep position sensor. Example: Wearing a chest‑mounted device that vibrates when supine. Practical application: Often first step before CPAP in mild positional OSA. Challenges: Patient adherence; effectiveness wanes with severe OSA.
Power‑Line Interference – 50/60 Hz noise from electrical sources affectin… #
Related terms: artifact, filtering. Example: EEG trace shows rhythmic spikes at 60 Hz. Practical application: DSP filters remove interference to preserve signal integrity. Challenges: Over‑filtering may erase genuine high‑frequency activity.
Pre‑Test Probability – estimated likelihood of disease before testing, ba… #
Related terms: risk stratification, screening criteria. Example: High pre‑test probability in a snoring, hypertensive male. Practical application: Determines whether HST is appropriate or PSG is required. Challenges: Subjectivity; may lead to over‑ or under‑utilization.
Pressure‑Release Ventilation (PRV) – a mode that automatically reduces pr… #
Related terms: CPAP, BiPAP. Example: PRV lowers EPAP to 5 cm H₂O during exhalation. Practical application: Enhances tolerance for patients who cannot exhale against high pressure. Challenges: May compromise airway splinting if pressure drops too low.
Pulse Oximetry – non‑invasive measurement of peripheral oxygen saturation… #
Related terms: desaturation index, oximetry artifacts. Example: SpO₂ falls from 98 % to 85 % during an apnea. Practical application: Core component of both PSG and HST. Challenges: Motion artifact, poor peripheral perfusion, nail polish interference.
Rapid Eye Movement (REM) Sleep – sleep stage characterized by vivid dream… #
Related terms: EOG, REM‑predominant OSA. Example: AHI spikes during REM despite overall mild OSA. Practical application: Highlights need for full PSG when REM‑related apnea is suspected. Challenges: HST often cannot stage REM, risking missed diagnosis.
Recording Montage – arrangement of sensors and leads used during a sleep… #
Related terms: channel selection, setup protocol. Example: Standard PSG montage includes 6 EEG, 2 EOG, 1 EMG, and respiratory channels. Practical application: Determines data richness and diagnostic capability. Challenges: More channels increase setup time and patient discomfort.
Respiratory Effort Sensors – devices (e #
G., Thoracic and abdominal belts) that detect changes in chest and abdominal movement. Related terms: airflow, apnea classification. Example: Effort belts show continued movement during a flow cessation, indicating obstructive apnea. Practical application: Essential for differentiating obstructive from central events. Challenges: Belt slippage leads to inaccurate effort detection, especially in HST.
Respiratory Event Index (REI) – number of respiratory events per hour of… #
Related terms: AHI, recording time. Example: REI = 18 based on 6 hours of usable data. Practical application: Provides a proxy for AHI when total sleep time is not measured. Challenges: Over‑estimates severity if sleep time is shorter than recording time.
Sleep Architecture – the distribution of sleep stages (N1, N2, N3, REM) a… #
Related terms: sleep staging, sleep efficiency. Example: PSG shows 20 % N3, 25 % REM, and 55 % N2. Practical application: Abnormal architecture may signal comorbid disorders. Challenges: Not captured in most HST devices, limiting assessment of sleep quality.
Sleep Efficiency – ratio of total sleep time to time in bed, expressed as… #
Related terms: sleep latency, sleep fragmentation. Example: 6 Hours of sleep in an 8‑hour time‑in‑bed yields 75 % efficiency. Practical application: Low efficiency may prompt referral for full PSG. Challenges: Requires accurate sleep onset and offset detection.
Sleep Fragmentation – frequent arousals that disrupt continuity of sleep #
Related terms: micro‑arousal, sleep efficiency. Example: 20 Arousals per hour observed on PSG. Practical application: Correlates with daytime sleepiness and cardiovascular risk. Challenges: HST may miss subtle arousals without EMG.
Sleep Position‑Dependent OSA – OSA severity that varies with body posture… #
Related terms: positional therapy, supine AHI. Example: AHI = 35 supine vs 5 lateral. Practical application: Guides targeted positional devices. Challenges: Accurate position detection required; patient compliance may wane.
Sleep Study Report – formal document summarizing findings, interpretation… #
Related terms: diagnostic criteria, treatment plan. Example: Report lists AHI, ODI, sleep architecture, and CPAP prescription. Practical application: Serves as legal record and communication tool among providers. Challenges: Standardizing language across labs and HST vendors.
Sleep‑Disordered Breathing (SDB) – umbrella term for apnea, hypopnea, and… #
Related terms: OSA, CSA. Example: Patient presents with snoring, witnessed apneas, and daytime fatigue—indicative of SDB. Practical application: Directs clinicians to appropriate diagnostic pathway. Challenges: Heterogeneity makes one‑size‑fits‑all screening difficult.
Standardized Scoring Manual – guideline (e #
G., AASM Manual) that defines criteria for event identification. Related terms: inter‑rater reliability, scoring rules. Example: Manual specifies 4 % desaturation threshold for hypopnea. Practical application: Ensures uniformity across sleep centers. Challenges: Updates may create transition periods for equipment software.
Signal‑to‑Noise Ratio (SNR) – measure of signal strength relative to back… #
Related terms: artifact, data quality. Example: High SNR in airflow trace yields clear apnea detection. Practical application: Guides technologist decisions on repeat recordings. Challenges: Low SNR in HST due to home environment noise.
Sleep‑Stage Scoring – classification of each 30‑second epoch into N1, N2,… #
Related terms: EEG, sleep architecture. Example: Epochs with sleep spindles scored as N2. Practical application: Determines proportion of REM, influencing OSA severity assessment. Challenges: HST devices often lack EEG, limiting scoring.
Snoring Index – number of snoring events per hour, measured by acoustic s… #
Related terms: acoustic monitoring, vibration sensor. Example: Snoring index of 120 events/h correlates with moderate OSA. Practical application: Useful screening metric in dental practice. Challenges: Ambient noise can inflate counts; not specific for apnea.
Standard Home Sleep Test (Standard HST) – FDA‑cleared, limited‑channel de… #
Related terms: direct‑to‑consumer HST, clinical‑directed HST. Example: Device records nasal pressure, oximetry, and chest belt. Practical application: Enables rapid, low‑cost diagnosis. Challenges: Limited ability to detect CSA, hypoventilation, or comorbid arousals.
Statistical Agreement – measurement of concordance between two diagnostic… #
G., PSG vs HST). Related terms: kappa coefficient, bias. Example: Kappa of 0.78 Indicates substantial agreement for moderate‑to‑severe OSA detection. Practical application: Validates HST utility in clinical protocols. Challenges: Agreement may decline in mild disease ranges.
Standardized Sleep Questionnaire (SSQ) – a validated tool (e #
G., STOP‑BANG) used to assess risk of OSA. Related terms: screening, clinical assessment. Example: STOP‑BANG score of 5 suggests high risk. Practical application: Helps prioritize patients for PSG or HST. Challenges: Cultural differences affect responses; false‑negatives possible.
Staged PSG – a polysomnography that includes a planned sequence of sleep… #
Example: AHI reduces from 30 supine to 8 lateral. Practical application: Identifies candidates for positional therapy. Challenges: Requires patient cooperation and technologist guidance.
Study Compliance – degree to which a patient follows device instructions… #
Related terms: adherence, data completeness. Example: 90 % Of recorded nights meet quality criteria. Practical application: High compliance improves diagnostic yield. Challenges: Poor compliance leads to repeat testing or referral to lab PSG.
Therapeutic Titration – process of adjusting PAP pressure to eliminate ev… #
Related terms: auto‑titrating CPAP, manual titration. Example: In‑lab titration raises CPAP to 12 cm H₂O to achieve AHI < 5. Practical application: Determines optimal therapeutic pressure before home use. Challenges: Requires skilled technologist; may differ from auto‑adjusted pressure.
Time in Bed (TIB) – duration from lights‑out to final awakening #
Related terms: sleep efficiency, sleep latency. Example: TIB of 8 hours with 6 hours of sleep yields 75 % efficiency. Practical application: Used to calculate sleep efficiency and REI. Challenges: Inaccurate self‑reporting can skew calculations.
Transient Arousal – brief EEG shift indicating a return to lighter sleep… #
Related terms: micro‑arousal, event‑related arousal. Example: 2‑Second EEG desynchronization following a hypopnea. Practical application: Contributes to AHI calculation and symptom burden. Challenges: Detecting transient arousals without EMG may be difficult.
Undiagnosed OSA Prevalence – proportion of the population with OSA who ha… #
Related terms: screening, public health. Example: Estimated 80 % of moderate OSA remains undetected. Practical application: Highlights need for accessible HST in dental practices. Challenges: Resource allocation and insurance coverage.
Upper Airway Resistance Syndrome (UARS) – condition characterized by incr… #
Related terms: sleep fragmentation, subtle OSA. Example: PSG shows frequent flow limitation with RERA events. Practical application: May respond to MAD therapy. Challenges: Frequently missed on HST lacking RERA detection.
Validated Diagnostic Algorithm – evidence‑based flowchart guiding clinici… #
Related terms: clinical pathway, decision tree. Example: Algorithm recommends HST for STOP‑BANG ≥ 3 and BMI < 30 kg/m². Practical application: Streamlines patient flow in dental sleep clinics. Challenges: Must be updated with emerging evidence.
Ventilatory Control Instability – fluctuations in the respiratory drive t… #
Related terms: loop gain, Cheyne‑Stokes respiration. Example: High loop gain contributes to CSA in heart failure. Practical application: Guides selection of adaptive servo‑ventilation. Challenges: Not directly measurable on standard HST.
Waveform Artifact – distortions in recorded signals caused by equipment o… #
Related terms: signal‑to‑noise ratio, data cleaning. Example: 60 Hz hum superimposed on ECG trace. Practical application: Requires filtering before scoring. Challenges: Excessive artifact may necessitate repeat study.
White‑Noise Calibration – technique using a known noise source to calibra… #
Related terms: signal calibration, sensor drift. Example: Calibration ensures nasal pressure transducer accuracy. Practical application: Maintains consistency across multiple HST devices. Challenges: Calibration errors lead to systematic bias.
Whole‑Night Recording – acquisition of physiological data from sleep onse… #
Related terms: full‑night PSG, recording montage. Example: 7‑Hour recording captures multiple sleep cycles. Practical application: Provides comprehensive data for accurate diagnosis. Challenges: Incomplete recordings reduce reliability.
Yield of Diagnostic Testing – proportion of tests that result in a defini… #
Related terms: diagnostic sensitivity, clinical utility. Example: HST yield of 70 % for moderate‑to‑severe OSA in high‑risk patients. Practical application: Informs cost‑effectiveness analyses. Challenges: Lower yield in low‑risk or comorbid populations.
Zero‑Leak Titration – technique ensuring no unintended air leaks during P… #
Related terms: mask fit, pressure leak test. Example: Leak rate < 5 L/min during titration. Practical application: Prevents over‑estimation of required pressure. Challenges: Patient movement may introduce intermittent leaks.
Z‑Score Normalization – statistical method to compare a patient’s sleep p… #
Related terms: standard deviation, normative data. Example: AHI Z‑score of +2 indicates two standard deviations above mean. Practical application: Helps clinicians communicate severity. Challenges: Requires robust normative databases specific to age, sex, and ethnicity.