2The following presentation is being provided for informational and educational purposes only. While Compumedics endeavors to ensure the validity and accuracy of the information within, we cannot be held responsible for inaccuracies, opinions or practices that often vary between various experts or are without established acceptable medical standards. Please consult your own medical director for clarification or for policies that are specific to your facility. We welcome your comments, suggestions and corrections. Pleaseyour comments to:
3Why Perform Sleep Studies? Quantify sleep patternDetermine cause of excess daytime sleepinessInitialize and evaluate treatmentEvaluate treatment effectiveness
4Types of sleep studiesDiagnostic - investigative study to determine if there are identifiable problems with the patient’s sleepCPAP titration - once a patient is identified as having sleep apnea, another study is performed in which the technician adjusts the CPAP/BiPAP level during the test and decides which mask and type of treatment is bestSplit Night - combines a diagnostic study and a titration study into one night. The patient is diagnosed during the first half of the night; CPAP/BiPAP applied the second half if required by protocolMSLT - Multiple Sleep Latency Test (nap study)MWT – Maintenance of Wakefulness Test
5Diagnostic Sleep Studies – Variables Evaluated Sleep stagingWake, NREM (N1,N2,N3), REMArousalsRespiratoryApneas and hypopneasUpper airway resistanceLimb EMGPLMSRestless legs
6Polysomnography (PSG) Typical MontageEEG F4-M1, EEG C4-M1, EEG O2-M1, EOG-L(E1), EOG-R(E2), EMG (chin)AIRFLOW, both Thermal and Nasal PressureTHOR EFFORT, ABDO EFFORTSpO2,ECG,LEG(L), LEG(R)SOUND, POSITIONCPAP pressure and flowOptional: additional EEG, dB meters, temperature, blood pressure
8Sleep Architecture Normal? Deficient in REM? Contain supine REM? Deficient in Delta sleep?Fragmented or disrupted by frequent arousals?
9Normal Sleep Architecture Entered through NREMApproximately 90 minute cycle including NREM and REMSlow wave dominates first third of nightREM sleep dominates last third of nightREM sleep: 20-25% total sleep time
11Sleep Staging Variables Electroencephalogram (EEG) - acquired by surface electrodes on the scalp at standardized locations (10-20 system)Electrooculogram (EOG) - acquired by surface electrodes placed at the outer canthus of each eyeElectromyogram (EMG) - acquired by surface electrodes placed on the chin muscle (sub-mental)
13EEG Frequency and amplitude change with sleep stage: Wake: high frequencyStage N1 and REM: low amplitude, mixed frequencyStage N2: spindles, K-complexesStage N3: delta waves (slow frequency, high amplitude)Standard sleep epoch is 30 seconds (10 mm/sec paper speed)
21EMGRecorded as the potential between two surface electrodes placed several centimeters apartTypically, the chin (submental) muscle is used because it exhibits large differences during sleep, aiding in the identification of stagesWake - high activitySleep - lower activityREM sleep - paralysis of skeletal muscles
22EMG Placement Submental (chin) AASM placement = one midline and two under the chin
29Airflow Used for detecting respiratory events Apnea: no airflowHypopnea: reduced airflowHow is airflow commonly measured?Temperature changes: thermistor/thermocouple – used for apnea detectionIn/ex pressure changes: nasal cannula – used for hypopnea detectionETCO2 – most often used in pediatrics
30Respiratory Effort Used for classifying respiratory events e.g. Apnea: no airflow but effort indicates obstructionInductive plethysmography bands – AASMPiezo-electric bandsEMG: diaphragm/intercostalEsophageal pressure
31Other Respiratory Variables Gases:SpO2 – Blood oxygen level (%) by oximetrytcCO2 – Transcutaneous CO2etCO2 – End Tidal CO2Arterial CO2 – blood analysis
32Other Variables Typically Recorded ECGLeg movement: EMG (AASM), piezoelectricVideoBody positionCPAP flow and pressure (DC input)
33Respiratory Events Apneas Obstructive Central Mixed Hypopneas Respiratory Event Related Arousals - RERARespiratory event does not meet the criteria for event types aboveCauses a disruption of the sleep architecture (arousal)
34Obstructive Apnea Cessation of airflow for more than 10 seconds With abdominal and/or thoracic effortUsually terminated by an arousal and/or associated with a desaturation
36Central Apnea Cessation of airflow, usually for more than 10 seconds Without abdominal and/or thoracic effortMay be terminated by an arousal and/or associated with a desaturationVery different type syndrome than OSA; chemo-receptor irregularities
38Mixed ApneaCessation of airflow >10 s (in adults) with respiratory effortContains both central and obstructive components, with each component lasting at least one normal respiratory cycleTypically leads to a desaturation and an arousalIs really just a type of obstructive event with the same consequences
43PLMSRepetitive (at least 4) episodes of muscle contraction ( s duration)Minimum amplitude increase of 8 uV above baselineSeparated by > 5 seconds, but not more than 90 secondsArousals sometimes associated with the movementsPositive diagnosis if more than 5 per hour of sleepMovements may be clinically significant only if associated with arousals
47ECG Normal sinus rhythm? Bradycardia or Tachycardia? Frequent atrial/ventricular arrhythmias?Run of 5 or more ventricular arrhythmias?
48ECG – AASM Reporting Average heart rate during sleep Highest HR during recording/sleepBradycardia < 40 bpm (lowest observed)Sinus Tachycardia > 90 bpm (highest observed)Narrow Complex Tachycardia (highest observed)Wide complex Tachycardia (highest observed)Asystole, longest pauseAtrial fibrillationList other arrhythmias
49Basic Steps to Analyze a Study Using Compumedics Software 1. Automatic AnalysisSleep StagingArousal ScoringRespiratory ScoringPLM Scoring2. Manual EditingValidate Sleep StagingEvent Editing: Respiratory, PLM, and ECGArousal Classification and editing3. Reporting4. Archiving
50Sleep architecture What was the sleep efficiency? What was the percent of each stage of sleep?What was the sleep onset time?What was the REM onset time?
51Respiratory Events Which events were most common? Were there any obstructive events?What was the AHI (Apnea/Hypopnea Index)?What was the RDI (Respiratory Disturbance Index) Apnea + Hypopnea + RERA per hour of sleepWhat was the nadir and baseline SpO2?Was any snoring recorded?
52Leg Movements Were they periodic? What was the index (number per hour of sleep)Did they cause arousals?
53Arousals How many per hour? Related to events?? Respiratory events Leg movementsEsophageal refluxSeizuresUnknown (spontaneous)