Interpretation of Polysomnography •Used in conjunction with comprehensive sleep
evaluation
Polysomnography is a comprehensive recording •In patients with high pre-test probability of
of biophysiological changes that occur during moderate to severe OSA
sleep. •Without co-morbid sleep disorders or medical
disorders like pulmonar ydisease, neuromuscular
PSG includes disease, or congestive hear tfailure (Evidence
1.identication of sleep stage Quality A, Strong Recommendation).
2.Analysis of patterns of respiration
3.Analysis of movement patterns Other indications for unattended portable sleep
study:
What are various types of sleep studies? a. Severe clinical symptoms indicate OSA
•Type 1: Fully attended polysomnography (≥ 7 and initiation of treatment is urgent and
channels) in a laboratory setting PSG is not readily available
•Type 2: Unattended polysomnography (≥ 7 b. Patients are unable to be studied in the
channels) sleep laboratory (safety or immobility)
•Type 3: Limited channel study (using 4–7 c. As a follow-up study when the diagnosis
channels) of OSA was previously established by
•Type 4: One or two channels usually using PSG and the intent of testing is to
oximetry one of the parameters evaluate the response to therapy (weight
loss, surgery, oral appliance)
INTERPRETATION AND MONITORING OF
RESPIRATORY EVENTS
RESPIRATORYSENSORS
•The sensor to detect absence of airflow in
apnea is the oronasal thermal sensor.
•The sensor for detection of airflow for
identification of hypopnea is a nasal air pressure
transducer
•The sensor for detection of respiratory effort is
either esophageal manometry or calibrated or
uncalibrated inductance plethysmography.
• The sensor for detection of blood oxygen is
pulse oximetry.
• Level 1 study or in-hospital, in-laboratory, COMPARING 2007 AND 2012 AASMRULES
technician-attended, overnight polysomnography
(PSG) is the “Gold standard” for evaluation of
sleep- disordered breathing (Evidence Quality A,
Strong Recommendation).
•Level 1 polysomnography remains the
cornerstone for the diagnosis in patients of
comorbid sleep disorders, unstable medical
conditions or complex sleep-disordered breathing.
• Laboratory-attended PSG (level 1) is not
necessary in all patients suspected to have OSA.
•Portatable monitoring with devices (which should Typesof apneas
at least include airflow, oxygen saturation and •Obstructive apnea: If the event meets apnea
respiratory effort) is adequate for diagnosis if criteria and associated with continued or
increased inspiratory effort throughout the entire Removed: 90% of event duration must meet
period of absent airflow. amplitude reduction criteria.
•Central apnea: If the event meets the apnea
criteria and associated with absent inspiratory No Alternative Rule
effort through the entire period of absent airflow.
•Mixed apnea: If the event meets apnea criteria Added: Definitions for scoring obstructive and
and is associated with absent inspiratory effort in central hypopnea. Scoring hypopneas as
the initial portion of event followed by resumption obstructive or central is optional
of inspiratory effort in the second portion of event
Cheyne Stokes Breathing
HYPOPNOEA RULES-2007
Criteria 1: When all of the following criteria are
made
•Nasal pressure signal excursions drop by ≥30%
of baseline.
•Duration of drop occurs for a period lasting at
least 10 seconds.
•≥ 4% desaturation from pre-event baseline
•At least 90% of event duration must meet
amplitude reduction criteria for hypopnea.
Criteria 2: When all of the following criteria are
met
•Nasal pressure signal excursion drop by ≥ 50%
from baseline.
•Duration of drop for a period lasting at least 10
seconds
• ≥ 3% desaturation from pre event baseline or
event is associated with arousal
•At least 90% of event duration must meet the
amplitude reduction criteria for hypopnea.
Respiratory effort related arousal
HYPOPNEARULE-2012 • Sequence of breaths lasting at least 10 seconds
1. Nasal pressure signal excursions drop by > characterized by increasing respiratory effort or
30% in air flow from pre event baseline flattening of the nasal pressure waveform leading
2. Duration of this drop occurs for > 10 seconds to an arousal from sleep when the sequence of
3. > 3% oxygen desaturation or event is breaths does not meet the criteria for apnea or
associated with an arousal hypopnea.
•Use of esophageal pressure is preferred method
of assessing change of respiratory effort.
HYPOVENTILATION RULE
DOWN TITRATION
A “down” titration is recommended due to the
“hysteresis” phenomenon. During upward
titration, the PAP level at which flow limitation
disappears is 2-5 cm H2O higher than the level at
which it reappears during downward titration. If a
“down” titration is implemented, at least one “
up-down” CPAP titration (1 cycle) should be
conducted during the night. It should be
conducted when at least 30 min has elapsed
without obstructive respiratory events. CPAP
should be decreased by more than 1 cm H2O
with an interval no shorter ter than 10 min, until
there is reemergence of obstructive respiratory
events.
Titration guideline for when and how to switch
to BIPAP
DESCRIPTION AND METHODOLOGY OF 1. When the patient complains that he/she is
MANUAL PAPTITRATION uncomfortable or is intolerant of high CPAP
pressures. (Document this on the record.)
2. When CPAP level is 15 cm H2O and respirator
ydisturbances continue. (Document this on the
record.)
Begin BPAP at EPAP 4 cm H2O or the CPAP
level at which obstructive apnea was eliminated;
Increase pressure by one cm of water at an set IPAP 4 cm H2O higher.
interval of no less than five minutes in following
cases
• Increase both IPAP and EPAP pressures by a Types of Titration achieved
minimum of 1 cm H2O with an interval of no less 1. Optimal
than 5 minutes when the following occur: 2. Good
3. Acceptable
4. Unacceptable
Optimal titration is achieved when:.
1. The Respiratory Disturbance Index (RDI) is <
5 per hour for a period of at least 15 minutes at
the selected pressure and within the
manufacturer’s acceptable leak limit.
• Increase IPAP pressure by a minimum of 1 cm 2. The SpO2 is above 90% at the selected
H2O with an inter val of no less than 5 minutes pressure.
when the following occurs : 3. Supine REM sleep at the selected pressure is
not continually interrupted by spontaneous
arousals or awakenings.
Good titration is achieved when
1. The Respiratory Disturbance Index (RDI) is <
10 per hour (or is reduced by 50% if the baseline
RDI was <15) for a period of at least 15 minutes.
2. The SpO2 is above 90% at the selected
pressure.
• Determining the Optimum Pressure 3. Supine REM sleep at the selected pressure is
• The patient must be able to sleep in order for not continually interrupted by spontaneous
PAP titration to be successful. If the patient arousals or awakenings.
awakens and complains the pressure is too high,
the pressure should be reduced to a level at Adequate Titration
which the patient is able to return to sleep. Which does not reduces overnight RDI<10 per
• Mask and mouth leaks should be promptly hour but reduces RDI>75% of baseline in severe
addressed. OSA patients or in which titration grading criteria
• Pressure relief technologies may be of optimal or good titration are achieved with
implemented to improve patient comfort. exception that supine REM does not occur at
• BPAP may be utilized for patients who are selected pressure.
intolerant of high CPAP pressures.
• Supplemental Oxygen when awake supine Split-Night Studies
SpO2 on room air is less than 88% for 5 minutes •Split-night studies must be performed using
or longer. Supplemental O2 may also be added algorithms identical to those used for full-night
during the PAP titration when SpO2 is ≤88% for PAP titration and should include greater than 3
≥5 minutes in the absence of obstructive hours of titration time.
respirator yevents •Split-night studies should not be performed on
•Supplemental oxygen should be introduced into children less than 12 years old.
the PAP device at the device connection using a •Due to the reduced titration time available during
T connector, not at the PAP mask. split-night studies, increase PAP pressures by a
•The recommended minimum starting rate for minimum of 2 cm H2O with an inter val of no less
adult and pediatric patients is 1 L/min. Titrate O2 than 5 minutes.
in 1 L/min increments with an inteal of no less
than 15 minutes until SpO2 is between 88% and INTERPRETATION OF EEG
94. •EEG electrode position determined by
international 10 -20 system.
•A minimum of 3 EEG derivations are required in
order to sample activity from frontal, central and
occipital regions. This system is based on the
relationship between the location of an electrode
and the underlying area of cerebral coex.
•"10" and "20" refer to the actual distances
between adjacent electrodes are either 10% or
20% of the total front– back or right–left distance
of the skull.
CHIN EMG-
• Three electrodes should be placed to record
chin EMG
• One in the midline one cm above the inferior
edge of the mandible.
•Recommended derivations are F4-M1,C4-M1, • One two cm below the inferior edge of mandible
O2-M1. and 2cm to right of midline.
•M1 and M2 refer to right and left mastoid process • One two cm below the inferior edge of mandible
and two cm to the left of mandible
EOG
SCORING OF SLEEP STAGES
Stages of sleep:
● Stage N1
● Stage N2
● Stage N3
● Stage R
•Scoring by Epoch-Scored in 30 second
sequential epoch
•Assign a stage to each epoch.
•If two or more stage coexist during single epoch,
assign the stage comprising the greatest por tion
of epoch
Frequency band width
Frequencies in polysomnography limited to 4
distinct patterns:
EEG scoring
STAGE N1
• Alpha rhythm is attenuated and replaced by
low amplitude mixed frequency activity more than
50% of epoch
• In subjects who do not generate alpha rhythm
score stage N1 with any of the following
phenomenon
• Activity in range of 4-7Hz with slowing of
background frequency by >_ 1Hz from those of
stage W v
• Vertex sharp wave
• Slow eye movements
STAGE W
More than 50% of epoch has alpha rhythm over
occipital region or any of the following are present
•Eye blink at a frequency of 0.5 -2 Hz
•Reading eye movement
•Irregular conjugate rapid eye movements
associated with normal or high chin muscle tone
STAGE N2 • Major body movement followed by slow eye
•Score N2 (in absence of criteria for N3) if one or movements and low amplitude mixed frequency
both occur in f irst half of epoch or last half of the EEG without nonarousal associated K complexes
previous epoch or sleep spindles
•One or more k complexes unassociated with • STAGE N3- When 20% or more of an epochs
arousal consists of slow wave activity irrespective of age.
•One or more trains of sleep spindles •Sleep spindles may persist in stage N3 sleep.
Continue to score epochs with low amplitude •Eye movements are not typically seen in N3
mixed frequency EEG activity without K sleep.
complexes or sleep spindles as N2 if they are • In N3 stage the chin EMG is of variable
preceded by K complex unassociated with amplitude often lower than in stage N2 sleep and
arousal or sleep spindle sometimes as low as in stage R sleep
K Complex: A well delineated negative sharp
wave immediately followed by a positive
component standing out from the background
EEG, with total duration or equal to 5 seconds,
usually maximal in amplitude when recorded
using frontal derivations
Sleep Spindle: A train of distinct waves with
frequency 11-16 Hz with a duration of and equal • 20% to 50% Delta Activity is seen
to 0.5 seconds usually maximal in amplitude •EOG leads will only pick up the EEG activity
using central derivations •EMG may be slightly lower than that of Stage
two
STAGER
• Low amplitude mixed frequency EEG
•Low chin EMG tone
•Rapid eye movements
•Saw tooth waves
End of N2 sleep when one of the following events
occur-
• Transition to stage W or N3 or stage R
MAJOR BODY MOVEMENTS-
•Movement and muscle artifact obscuring EEG
for>half of epoch to the extent that sleep stage
can not be determined
Score an epoch with major body movement as
follows
•If alpha rhythm is present for part of the epoch
score as stage W.
•Otherwise score the epoch as the same stage as
the epoch follows it.
PULSE TRANSIT TIME
•Pulse transit time (PTT) is the time taken for the
arterial pulse pressure wave to travel from the
aortic valve to a peripheral site. For convenience,
it is usually measured from the R wave on the
electrocardiogram to the pulse wave arrival at the
finger.
•Pulse transit time is inversely proportional to
blood pressure, and the falls in blood pressure
which occur with inspiration (pulsus paradoxus)
correspond to rises (lengthening) in pulse transit
time
• Pulse transit time may, therefore, provide a
clinically useful, noninvasive, and quantitative
measure of inspiratory effort for patients with
sleep-related breathing disorders.
