An Overview of Polysomnography

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Sleep Technology
An Overview of Polysomnography and the Roles and
Responsibilities of the Sleep Technologist
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• Everybody was excited, except the fat boy,
  and he slept as soundly as if the roaring of
  cannon were his ordinary lullaby Sleep! said
  the old gentleman, hes always asleep. Goes on
  errands fast asleep, and snores as he waits at
  table.
• Charles Dickens
• The Posthumous Papers of the Pickwick Club 1884

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Sleep Disorders are Common

• Over 80 different types of sleep disorders have
  been identified.
• About one-half of adults in the U.S. experienced
  a sleep problem a few nights per week or more
  during the past year.
• More than one-half of the adults surveyed report
  having experienced one or more symptoms of
  insomnia a few nights per week or more within the
  past year.
• Obstructive Sleep Apnea symptoms in occur in 1
  out of every 10 people.
• Only one-third of adults say they get at least
  the recommended 8 hours or more of sleep per
  night during the work week
• More than one-third of U.S. adults report snoring
  a few nights per week or more within the past
  year.
• A sizable proportion of adults (43) report that
  they are so sleepy during the day that it
  interferes with their daily activities a few days
  per month or more and, one out of five
  experience this level of daytime sleepiness at
  least a few days per week or more.

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Sleep Disorders are Serious

• Chronic insomniacs report decreased quality of
  life, memory and attention problems, decreased
  physical health.
• About one-half of adults in the U.S. report
  driving while drowsy in the past year nearly one
  out of five (17) have actually dozed off while
  driving.
• Total estimated annual costs of sleep disorders
  in U.S. 15.9 billion. (NCSDR)

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Sleep Disorders are Treatable

• Multiple successful treatment modalities exist,
  including pharmacotherapy, oral appliances,
  surgical intervention, behavioral therapy, and
  continuous positive airway pressure.

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Sleep DisordersConceptual Framework
Insufficient Sleep (Sleep Deprivation)
Fragmented Sleep (Sleep Disruption)
Excessive Daytime Somnolence
Primary Disorders of EDS
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Assessing Excessive Daytime Sleepiness

• Differentiate sleepiness vs fatigue
• Subjective perception of sleep tendency,
  especially in low stimulus conditions
• Sleepiness rating scales (subjective)
• Epworth Sleepiness Scale (ESS) most common
• Stanford Sleepiness Scale (SSS)
• Sleep-Wake Activity Inventory (SWAI)
• Objective measure of EDS Multiple Sleep Latency
  Test (MSLT) and Maintenance of Wakefulness Test
  (MWT)

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Sleep DisordersClinical Impact
Excessive Daytime Somnolence
Neurobehavioral Deficits
Performance Deficits
Increased Morbidity/Mortality
Decreased Quality of Life
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Sleep DisordersEtiologicFramework/ Clinical
Disorders

• Medical-psychiatric sleep disorders
• Medical
• Sleep-related asthma
• COPD
• G-E reflux
• Pain related
• Medication related
• Psychiatric
• Depression or panic disorder
• Neurological
• Sleep-related epilepsy
• Others
• Restless legs syndrome (RLS) and periodic limb
  movement disorder (PLMD)

• Dyssomnias - disorders of initiating or
  maintaining sleep
• Circadian rhythm disorders/shiftwork
• Narcolepsy
• Idiopathic hypersomnia
• Inadequate sleep hygiene
• Sleep-related respiratory disorders
• OSAHS, CSAHS, Cheyne-Stokes, periodic breathing
• Upper airway resistance syndrome
• Parasomnias
• Disorders of arousal
• Disorders of sleep-wake transition
• REM behavior disorder
• Nightmares
• Rhythmic movement disorder
• Bruxism

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Evaluating Sleep Disorders

• Overnight Polysomnogram (PSG)
• Split Night Study
• Multiple sleep latency testing (MSLT)
• Maintenance of wakefulness test (MWT)
• Limited-Channel PSG (pediatrics)
• Unattended (portable) PSG

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The Polysomnogram Whats Recorded

• Bio-electric Signals
• EOG - Electrooculogram
• EEG -Electroencephalogram
• EMG - Submental Electromyogram
• EKG - Electrocardiogram

• Transduced Signals
• Tracheal Noise
• Nasal and oral airflow
• Thoracic and abdominal respiratory effort
• Pulse oximetry
• Video (body position)
• limb movements via EMG
• end-tidal CO2, transcutaneous CO2
• Esophageal pH
• CPAP and BiLevel outputs

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Types of Equipment

• Electrodes
• Preps and Gels
• Lead wires
• Airflow sensors
• Respiratory effort
• Misc. Sensors
• Snoring/mike/body position/motion

• Amplifiers
• Headbox
• Software
• Oximeters
• pH meters
• Audiovisual
• PAP equipment

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Patient Set-up Components

• Sleep History
• Pre-Sleep Questionnaires
• Electrode and Sensor Placement
• Equipment Set-up and Calibration
• Biocalibrations
• Patient Monitoring
• Troubleshooting

• Reduce anxiety !!!

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The International 10-20 System

• The International 10-20 System of electrode
  placement is the most widely used method to
  describe the location of scalp electrodes.
• The 10-20 system is based on the relationship
  between the location of an electrode and the
  underlying area of cerebral cortex.
• Each site has a letter (to identify the lobe) and
  a number or another letter to identify the
  hemisphere location. 

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The International 10-20 System

• The letters used are  "F" - Frontal lobe, "T" -
  Temporal lobe , "C" - Central lobe , "P" -
  Parietal lobe, "O" - Occipital lobe.  (Note
  There is no central lobe in the cerebral cortex.
  "C" is just used for identification purposes
  only.)
• Even numbers (2, 4, 6, 8) refer to the right
  hemisphere and odd numbers (1, 3, 5, 7) refer to
  the left hemisphere. "Z" refers to an electrode
  placed on the midline. The smaller the number,
  the closer the position to the midline.

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The International 10-20 System

• "Fp" stands for Front polar. "Nasion" is the
  point between the forehead and nose. "Inion" is
  the bump at the back of the skull.
• The "10" and ""20" (10-20 system) refer to the
  10 and 20 interelectrode distance. 

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Electrode Placement for PSG

• EEG electrode placement for sleep studies are
  usually limited to C4, C3, A1, A2, O1, O2, LOC,
  ROC, and chin EMG.
• EEG, EOG, and EMG electrodes are necessary for
  staging sleep.

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Signals How we see them

• Signals from the patient are amplified using the
  sensitivity setting and are filtered with
• High frequency filter (HFF).
• Low frequency filter (LFF).
• Time constant (TC).
• Filters reduce unwanted activity.

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WAVEFORM VOCABULARY

• peak / crest - the highest point of a portion of
  a wave before it begins to decrease
• trough - the lowest portion of a wave
• rest - the horizontal line that would go through
  the center of a wave
• amplitude - the 'height' of the wave from either
  the crest or trough to the rest.
• cycle - from one point on a wave to its
  corresponding point as the wave cycle repeats
  (for example, from one trough to the next)
• frequency - the number of cycles passing by a
  given point in one second

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EEG MEASUREMENT AND CLASSIFICATION

• Frequency - cycles/second (Hz)
• Amplitude (microvolts)
• Presence of sleep-specific waveforms
• Vertex Sharp Wave
• Sleep Spindle, K complex
• Sawtooth wave
• Defined by duration and/or morphology

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Sleep Scoring

• All sleep recording studies follow the same
  guidelines
• Recording speed 10 mm/sec.
• One page 300 mm.
• Epoch 30 seconds.
• One minute two epochs.

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PSG Components - Summary

• Bio-electrical and transduced signals are
  transmitted, amplified, and filtered.
• Signals are combined (PSG) in a montage.
• Recording is divided into epochs (30 sec)
• Each epoch is assigned a sleep stage.
• The recording is analyzed for events.

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Alpha Activity

• Alpha EEG 8-13 cps.
• Alpha occipital region
• Alpha crescendo-decrescendo appearance
• Decrease in frequency occurs with aging

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Awake

• gt50 of each epoch contains alpha activity.
• Slow rolling eye movements or eye blinks will be
  seen in the EOG channels
• Relatively high submental EMG muscle tone

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Theta Activity

• A frequency of 3-7 cps.
• Produced in the central vertex region
• No amplitude criteria for theta
• The most common sleep frequency

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Stage WakeEyes Closed vs. Eyes Open
Eyes open
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Stage 1

• gt 50 of the epoch contains theta activity (3-7
  cps.) There may be alpha activity within
  lt50 of the epoch.
• Slow rolling eye movements in the EOG channels
• Relatively high submental EMG tone.

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K Complexes

• Sharp, slow waves, with a negative then positive
  deflection
• No amplitude criteria
• Duration must be at least .5 seconds
• Predominantly central-vertex in origin
• Indicative of stage 2 sleep

Sleep Spindles

• Sleep Spindle - 12-14 cps.
• Central - vertex region
• gt.5 to 2-3 seconds in duration
• .5 second spindles - 6-7 cycles
• Indicative of stage 2 sleep

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Stage 2

• Background EEG is Theta (3-7 cps.)
• K-Complexes and Spindles occur episodically
• Mirrored EEG in the EOG leads
• High tonic submental EMG

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Delta Activity

• Sleep Delta Activity - frequency of .5-2 cps.
• Clinical EEG - frequency of gt .5-4 cps.
• Seen predominantly in the frontal region
• Delta Activity - amplitude of gt 75mn

Delta EEG Activity (zoomed in 4 times larger than
normal)
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Stage 3
Read through the noise
75mn
1 sec.

• 20 to 50 of each epoch and must contain Delta
  Activity
• EOG channels will mirror Delta activity
• Submental muscle tone may be slightly reduced

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Stage 4
75mn

• gt50 of the epoch will have scorable Delta EEG
  activity
• The EOG leads will mirror all of the Delta EEG
  Activity
• Submental EMG activity will be slightly reduced
  from that of light sleep

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Stage REM

• Rapid eye movements
• Mixed frequency EEG
• Low tonic submental EMG

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Stage REM Phasic Twitching

• Very short muscle twitches that normally occur in
  REM Sleep
• May occur in the inner ear, genioglossal, limb,
  and facial muscles

The arrows are pointing to Phasic Twitching
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Sawtooth Pattern

• Jagged evenly formed EEG pattern seen usually in
  the vertex region
• Seen predominantly in REM

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Sleep Architecture

• During sleep, we move through the various stages
  in a general pattern.
• We have sleep cycles that include at least one
  NREM stage and one REM stage and last from 90 to
  110 minutes.
• During a night's sleep, the typical young adult
  experiences four to six sleep cycles, which
  change in composition as the night progresses.

• REM 25
• NREM 75 - Stage 1 5 - Stage 2 45
  - Stage 3 12 - Stage 4 13

• In the first third of the night, delta sleep
  stages are longer, and REM stages are shorter.
• In the last third of the night, delta sleep
  usually decreases from the NREM portion of the
  cycle, and REM sleep stages last longer.

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Sleep Architecture (contd)

• A typical sleeper's first sleep cycle moves from
  wakefulness through stages 1, 2, 3, and 4,
  consecutively.
• Then the sleeper moves back into stage 2 sleep
  and then into REM sleep.
• The conclusion of the REM stage ends the first
  sleep cycle.
• This first cycle usually lasts about 70 to 100
  minutes, typically the shortest of the cycles.
• This example is not absolute, but it does
  represent the norm.

• REM 25
• NREM 75 - Stage 1 5 - Stage 2 45
  - Stage 3 12 - Stage 4 13

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EKG Airflow Thoracic effort Abd. effort SpO2
Exhale
Airway obstructs
Airway opens
Effort gradually increases
Inhale
Paradoxing
Paradoxing Ends
Blood oxygen levels reduce to lt 3 of basline
value
Obstructive Apnea A complete blockage of the
airway (gt10 seconds) despite efforts to breath.
Notice the effort gradually increasing ending in
airway opening.
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Exhale
Airflow reduction
Inhale
gt effort with paradox
Paradox ends
SpO2 desaturation
Hypopnea This is a hypopneic event. The
airflow signal is reduced by approximately 50
during this event for at least 10 seconds. The
criteria for classifying hypopneas can vary from
lab to lab.
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ECG
Airflow
Thor. Effort
Abd. Effort
SpO2
Central Apnea These are central apneas (2)
with minimal oxygen desaturation. The criteria
for central apnea is no effort and no airflow for
at least 10 seconds.
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EKG
Airflow
Thoracic Effort
Abdominal Effort
SAO2
Mixed Apnea
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OSAHS Treatment Options

• CPAP (most common)
• Bi-Level
• Region specific surgery
• Tracheostomy
• Non-surgical alternatives
• behavioral modification
• pharmaceutical
• mechanical (dental devices)

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PAP TITRATION GOALS

• Eliminate Apnea
• Eliminate Hypopnea
• Eliminate Snoring
• Eliminate Desaturation
• Eliminate Arousals
• Increase Compliance

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End of Test Components

• Post Study Biocalibrations
• Electrode and Sensor Removal
• Post-Sleep Questionnaires
• Equipment Cleaning
• Documentation