Sleep Study Interpretation - Apsresp


Sleep StudyInterpretationGina S. de los Reyes, MD, MHPED,FPCCP, FPSSM

Outline Indications for PSGHook-up, preparation for PSGTypes of sleep studies Diagnostic, titration, split nightIndices derived from PSGApproach to reading sleep study reports

Polysomnography Single most important laboratorytechnique used in the diagnosis &treatment of sleep disorders The technique of recording, analyzing, &interpreting multiple simultaneousphysiologic characteristics during sleep

Indications Excessive daytime sleepinessObstructive sleep apneaBreathing difficulties during sleepBehavior disturbances during sleepPoor sleep quality or Insomnia to excludeother sleep disorders

Parameters monitored in PSG Sleep ParametersEEG EOG EMG Cardiopulmonary ParametersECG Air Flow Effort SaO2


Input 1(Exploring electrode)Differential Amplifier -Input 2 (Reference electrode)Moving PaperAmplitudeuV1 secTimeCycles per second or Hz

EEG Frequency BandsAlpha Beta Delta Theta 8 to 13 Hz 13 Hz 4 Hz (0.5-2Hz)4 to 7 Hz

Alpha waves-8-13 cps

Beta waves- 13 cps

Theta waves -4-7cps

Sleep spindleK complexSleep spindleK complexes 12-14 cps;-negative sharp waveimmed ffd by a positivecomponent at least 0.5 secduration; ie. 6-7distinct waves w/inthe half second 0.5sec, maximal oververtex regions

Delta waves 0.5 to 2 cps 75 uV

Sleep StagesStage WNon- REMStage N1Stage N2Stage N3Stage R*AASM Manual, 2007

STAGE WAKE Eyes closed-alpha waves ( 50%) Eyes open – low voltage mixed frequency Relatively high tonic EMG

STAGE N1 Low voltage, mixed freq activity, 2-7cps range amount( 50%), amplitude, freq of alpha Decreased tonic EMG With SEM; Without REM

K complexSleep spindleK complexSTAGE N2 Background of low voltage,mixed freq activity Presence of spindle and/or Kcomplex Delta waves 20% of epoch

STAGE N3 Moderate amounts of high amp, slowwave activity, delta waves occupying 20% epoch

STAGE REM Low voltage, mixed freq activity EOG- paroxysmal, relatively sharplycontoured, high-amplitude activity EMG- lowest tone in the record absence of spindles, K complexes,& delta

AROUSALS Abrupt shift in EEG freq (theta, alpha &/or freq 16hz but notspindles) EEG freq shift duration of / 3 secs Previously asleep for / 10secs

Sleep Stage SummaryHypnogramREM sleepStage N3, Slowwave sleep

Tonsillar size scoringMallampati grading

EPWORTH SLEEPINESS SCALESituationChance of Dosing (0-3)Sitting and reading0123Watching television0123Sitting inactive in a public place – ex theateror meeting0123As a passenger in a car for an hour without abreak0123Lying down to rest in the afternoon0123Sitting and talking to someone0123Sitting quietly after lunch (when you’ve had noalcohol)0123In a car, while stopped in traffic0123TOTALSCORE0 would never dose1 slight chance of dozing2 moderate chance of dozing3 high chance of dozingESS 10


Apnea temporary absence or cessation ofbreathing (airflow) during sleep; 10secsCENTRAL APNEA – no effort to breathe ismade OBSTRUCTIVE APNEA – there is ventilatoryeffort but no airflow because the upper airwayis closed MIXED APNEA- initially no ventilatory effortbut an obstructive apnea pattern is presentwhen effort resumes




HYPOPNEA1. Decrease in nasal pressureamplitude 30% from baseline2. with oxygen desaturation of 3% oran arousal3. event / 10s

RERA1. Increasingrespiratory effortor flattening ofnasal pressurewaveform2. event / 10s3. Followed by anarousal

Apnea/Hypopnea IndexApnea/Hypopnea index – apneas hypopneas /total sleep time # Apneas # Hypopneas x 60TST in minutes 0-5/hr Normal 5-15/hr Mild 15-30/hr Moderate 30/hr Severe

Types of Sleep Studies Diagnostic – investigative study to determine ifthere are identifiable problems with the patient’ssleepCPAP Titration – once the patient is identifiedas having sleep apnea, another study isperformed in which the technician adjusts theCPAP level during the testSplit Night- combines a diagnostic study & aCPAP titration study into one night.

Positive Airway PressureIV.41

Positive Airway PressureIV.42

Indices derived from PSGSleep Related Indices Time in Bed (TIB) Total recording time (TRB) Total sleep time (TST) Sleep Efficiency 90% Sleep Latency 20 mins REM latency90-120 mins Wake after Sleep Onset (WASO) Sleep Period Time (SPT) 20 mins

Indices derived from PSGDistribution of Sleep:Stages of SleepN1N2N3REM (R)Percentage of TST5%(3-8%)50% (45-55%)20% (15-20%)25% (20-25%)

Indices derived from PSGArousals Total arousal index Respiratory arousal index Periodic limb movement (PLM) ArousalIndex 15/hr Respiratory Effort Related Arousals(RERA)

Indices derived from PSGAbnormal activity during the study Periodic Limb movements index (PLMI) Bruxism ECG

Indices derived from PSGRespiratory Indices Apnea Hypopnea index (AHI) RERA index Respiratory Disturbance Index (RDI) Oxygen saturation indices

Apnea/Hypopnea IndexApnea/Hypopnea index – apneas hypopneas /total sleep time # Apneas # Hypopneas x 60TST in minutes 0-5/hr Normal 5-15/hr Mild 15-30/hr Moderate 30/hr Severe

Factors affecting interpretation Sleep Quantity & Quality – decreasedsleep quantity & poor sleep efficiency willoverestimate AHIAbsent REM sleep – underestimate AHIsince apneas & hypopneas tend to beworse in REM sleep when respiratorymuscles are more hypotonic

Factors affecting interpretation Position –apneas & hypopneas tend to beworse in supine position due to the base oftongue & soft palate falling back moreeasily when supine

Case 1 50/M with HPN, DMexcessive daytime sleepiness with snoring& witnessed apneas during sleepBMI 35.5ESS 18Nose: no septal deviation; normalturbinatesSoft palate low, tonsils: Grade 3;Mallampati score: 4

Total sleeptime463.5 min%Stage N313.5%Time in bedSleepEfficiency508.0 min91.2%%REMArousalIndex22.2%45.4/hTSTPLMIREM AHI2.8/h81.6/hrLowest satn 79%NREM AHI70.4/hrAHI72.9/hr

Question 1 What is the severity of OSA?A. MildB. ModerateC. SevereD. Very severe

Apnea/Hypopnea IndexApnea/Hypopnea index – apneas hypopneas /total sleep time # Apneas # Hypopneas x 60TST in minutes 0-5/hr Normal 5-15/hr Mild 15-30/hr Moderate 30/hr Severe72.9/hr

Case 2 32/M with no previous medical problemsexcessive daytime sleepiness with snoring& witnessed apneas during sleepBMI 27.5ESS 14Nose: hypertrophic inferior turbinates;Soft palate low, tonsils: Grade 1;Mallampati score:3

Total sleeptime429 min%Stage N35.0%Time in bedSleepEfficiency475 min90.3%%REMArousalIndex17.0%11.3/hrPLMIREM AHI3.1/h46.8/hrLowest satn 88%NREM AHI4.1/hrAHI13.8/hr

Question 2 What is your impression?A. Position dependent OSAB. REM dependent OSAC. Severe OSAD. Primary snoring

Case 3 55/F with HPN, CAD, dyslipidemic, s/p Coronarybypass surgery.Loud snoring, choking episodes during sleep,falls asleep while drivingBMI 38.5, neck circumference 42.5 cm, ESS of16/24.Nose: normal turbinatesSoft palate low, tonsils: Grade 2;Mallampati score: 4

Question 3 What type of sleep study will you request?A. Unattended portable sleepmonitoringB. CPAP titration studyC. Split night studyD. Multiple Sleep Latency test

Portable sleep monitoringType IIIType IV

Limitations of Portable Monitoring Inability to assess sleep architectureREM sleep and/or supine related OSAundetectedArousals, RERA’s not detectedPotential misdiagnosis if comorbid conditionspresent (ie. COPD, CHF, hypoventilation)AHI underestimated In-lab PSG: AHI apneas hypopneas/hours of sleep PM : AHI apneas hypopneas/hours recording timeSleep Medicine Clinics 2011; 6: 261-385

The “Split Night” Challenge You need to monitor the severity of apnea in thefirst half of the night to determine if criteria aremetYou will have a limited amount of time to titratethe patient

AASM Split Night Rules An AHI of at least 40 is documented during aminimum of 2 hours of diagnostic PSG. considered at an AHI of 20 to 40, based onclinical judgment (e.g., if there are also repetitivelong obstructions & major desaturations). at AHI values below 40, determination of CPAPpressure requirements, based on split-nightstudies, may be less accurate than in full-nightcalibrations.

Case 3 cont A split night study was doneDiagnostic144.0Titration450.0REM mins15.0140.0SWS duration53.521.5Sleep Efficiency62.390.3RDI (avg # / hr TST)81.63.4Minimum SpO2 duringsleep (%)50%70%TST

Therapy distributionIPAPLevel(cmH2O)EPAPTotalSleepLevel Duration Pos 1 S(% Dur)SnoreResp(% Total (ASPT) H .015.0 100.0 100.072.0100.018.558.29920.020.0100 0.00.21111150.0137.591.647.294.0100.00.00.6

Night Hypnogram

Question 4 What is your pressure recommendation?A.B.C.D.CPAP at 7 cm of waterCPAP at 8 cm of waterCPAP at 9 cm of waterCPAP at 10 cm of water

Titration guidelines The pressure of CPAP or BPAP selected for patientuse following the titration study should reflect controlof the patient's obstructive respiration by: a low (preferably 5 per hour) respiratorydisturbance index (RDI) at the selected pressure, a minimum sea level SpO2 above 90% at thepressure and with a leak within acceptable parameters atthe pressure

Titration guidelines Optimal titration reduces RDI 5 for at least a 15-min durationand should include supine REM sleep at theselected pressure not continually interrupted by spontaneousarousals or awakenings titration duration should be 3 hr

Question 5 When will the patient need a follow-upPSG?A. change in weight by 10%B. recurrence of symptomsC. intolerance of CPAP therapyD. All of the above

Follow-up PSG is indicated for After substantial weight loss (e.g., 10% ofbody weight) to ascertain whether CPAP is stillneeded at the previously titrated pressure After substantial weight gain (e.g., 10% ofbody weight) has occurred in patients previouslytreated with CPAP successfully, who are againsymptomatic despite the continued use ofCPAP, to ascertain whether pressureadjustments are neededSLEEP, Vol. 28, No. 4, 2005

Follow-up PSG is indicated for When clinical response is insufficient orwhen symptoms return despite a good initialresponse to treatment with CPAP. Follow-up polysomnography is NOTroutinely indicated in patients treated withCPAP whose symptoms continue to be resolvedwith CPAP treatment.SLEEP, Vol. 28, No. 4, 2005

Key Points PSG is the gold standard in the diagnosis ofobstructive sleep apnea & other sleep disordersReport must be interpreted in the proper contextof patient’s clinical scenarioWhen looking at a report examine the quantityand quality of sleep, REM sleep, and positionthat may affect interpretationOptimal titration is reached when RDI 5, oxygensaturation 90% & include supine REM.


Types of Sleep Studies Diagnostic –investigative study to determine if there are identifiable problems with the patient’s sleep CPAP Titration –once the patient is identified as having sleep apnea, another study is performed in which the technician adjusts the CPAP level during