This document provides definitions and explanations of key terms and metrics used in interpreting polysomnography tests. It describes signs and symptoms that indicate the need for a polysomnogram and defines measurements of sleep periods, stages, efficiency, and latency. It also defines the various types of respiratory events that can be observed, such as apneas, hypopneas, and arousals, and how they are calculated and classified. Finally, it outlines the process for reviewing sleep study results and making a diagnosis.

1. Interpretation of
Polysomnography
 Presented By
Dr. MD ABDULLAH SALEEM
MBBS, MD(Pulmonary Medicine)

2. Signs and Symptoms
 The signs and symptoms(EDS associated
with fatigue or impaired concentration
,unrefreshing sleep,choking or gasping
during sleep,recurrent awakenings from
sleep) helps in determining the patient’s
overall need for the polysomnogram as
well as their chief complaint.

3. Time in bed
 Time in bed is the total number of minutes
that a patient spends in bed. This amount
varies for different age groups and can
also vary on an individual patient basis.
This is important because it gives a basic
idea as to whether or not the patient is
spending enough time attempting to sleep.

4. Total Sleep Time
 Total sleep time is the actual amount of sleep
time in a sleep period ; equal to total sleep
period less movement and awake time. Total
sleep time is the total of all REMS and NREMS
in a sleep period. This is important because it
gives a basic idea as to whether or not the
patient is achieving enough sleep for the time
they are in bed.

5. Sleep Efficiency
 Sleep efficiency is the proportion of sleep
in the period potentially filled by sleep, that
is, the ratio of total sleep time to time in
bed.
 Normal is >80%This is important because
it displays the patients overall quality of
sleep as it pertains to any sleep disorder
they exhibit.

6. Sleep Latency
 Sleep latency is the period of time measured
from “lights out”, or bedtime, to the
commencement of sleep. This is important
because it can show the level of sleepiness by
how fast the patient gets to sleep or their sleep
latency (<30 minutes)
 It can also help to determine insomnia in
patients that displays signs of excessive daytime
sleepiness but do not achieve sleep in a timely
manner.

7. REM Latency
 Is the period of time measured from “lights
out”, or bedtime, to the commencement of
REM sleep (70-120 minutes)

8. Wake Percentage
 Wake percentage is the percentage of
wake scored from lights out to the final
wake-up. This is important because it will
help determine how much any sleep
disorder is affecting the patient’s sleep
architecture.

9. Stage 1
 Stage 1 is a stage of NREM sleep that ensues
directly from the awake state. It’s criteria
consists of a low-voltage EEG with slowing to
theta frequencies, alpha activity less than
50%,EEG vertex spikes, and slow rolling eye
movements. Stage 1 percentage is the total time
spent in stage1 sleep from lights out to the final
wake-up. Stage 1 generally constitutes about 4-
5% of sleep.

11. Stage 2
 Stage 2 is a stage of NREM sleep characterized
by the advent of sleep spindles and K
complexes against a relatively low-voltage,
mixed-frequency EEG background, high-voltage
delta waves may compromise up to 20% of
stage 2 epochs. Stage 2 percentage is the total
time spent in stage 2 from lights out to the final
wake-up. Stage 2 generally constitutes 45-55%
of sleep.

13. Stage 3
 Stage 3 is a stage of NREM sleep defined by at
least 20% of the epoch consisting of EEG waves
less than 2 Hz and more than 75 Micro V , it
constitutes deep NREM sleep. Stage 3
percentage is the total time spent in stage 3 from
lights out to final wake-up. Stage 3 sleep is
usually constitutes 12-18% of sleep.

16. REM Sleep
 REM sleep consists of low-voltage, mixed
frequency EEG which may be accompanied by
both saw-tooth waves and rapid eye
movements. REM percentage is the total time
spent in REM sleep from lights out to the final
wake-up. REM sleep usually constitutes 20-25%
of sleep in 4 to 6 episodes.

18. REM latency
 REM latency is the period of time from
sleep onset to the first appearance of REM
sleep. This is important in showing a short
onset of REM sleep, which is a sign of
Narcolepsy.

19. Respiratory Events
 Respiratory events is the breakdown of the
respiratory changes recorded during the
entire polysomnogram.

20. Obstructive Apneas
 Obstructive apneas are respiratory episodes where there
is a complete cessation of airflow lasting greater than 10
seconds associated with thoracic and abdominal efforts

21. Hypopneas
 Hypopneas are a respiratory episode where
there is partial obstruction of the airway lasting
greater than 10 seconds (30% fall in nasal
flow)and accompanied by a 4% desaturation

22. Central Apneas
 Central Apneas are respiratory episodes
where there is no airflow and no effort to
breathe lasting greater than 10 seconds.
Atleast >5 events per hour

23. Mixed Apneas
 Mixed Apneas are respiratory episodes
where there are features of both
obstructive and central apneas in the
same event.

24. Total events
 Total events is the total number of
Obstructive apneas, Hypopneas, Central
apneas, and mixed apneas from lights out
to the final wake-up.

25. RERA
 characterized by marked decreased in
airflow for at least 10 secs with increased
respiratory effort, no significant
desaturation and which leads to an
arousal from sleep.

26. CENTRAL SLEEP APNOEA
SYNDROME
 If > 50% of events are purely central =
CSAS

27. Cheyne Stokes breathing

28.  Cyclical crescendo and decrescendo
breathing pattern for 3 consecutive cycles
associated with
 A.5 or more Central sleep apnoea or
hypopnoea per hour or
 B.Cyclical crescendo and decrescendo
breathing pattern has duration of atleast
10 minutes

29. RDI
 RDI is an abbreviation for Respiratory
Disturbance Index. This number is the average
number of respiratory events per hour of sleep.
 APNOEA+HYPOPNOEA+CENTRAL APNOEA+
RERA
 Any RDI lower than 5/hr is considered to be
within normal limits.

30. REM RDI
 REM RDI is the total number of respiratory
episodes per hour of REM sleep.

31. Supine RDI
 Supine RDI is the number of respiratory
episodes per hour of supine sleep. This is
important because the patient may have
only positional apnea and therefore can be
treated with positional therapy.

32. Oxygen (SaO2)
 Baseline = the baseline oxygen level for
the entire polysomnogram.
 Low = the lowest oxygen level recorded
during the polysomnogram.

33.  UARS: > 5 RERA’s per hour of sleep

34. Arousals
 Abrupt change of EEG from a deeper stage of
NREM sleep to a lighter stage, or from REM
sleep toward wakefulness, with the possibility of
awakening as the final outcome
 An arousal may be accompanied by increased
chin (EMG) activity and heart rate, as well as by
an increased number of body movement

35.  Minimum duration is 3 secs
 Types: respiratory, PLMs, spontaneous
 Increased arousals are associated with
increased daytime sleepiness and
decreased performance, similar to that
seen in sleep deprivation

36. EKG abnormalities during sleep
 Heart rate too fast (tachycardia) or too
slow (bradycardia)
 Heart rhythm irregular
 Pauses

37. Miscellaneous
 The miscellaneous category is for other
important information regarding the
patient’s polysomnogram.

38. Periodic Limb Movements
 No of PLMS = the total number of periodic limb
movements during the polysomnogram.
 Limb movement should be of atleast 0.5 to 10
seconds and > 75 MicroVolts
 4 successive limb movements separated by
duration of least 5 to 90 seconds between each
movement
 PLMS Index = the average number of PLMS per
hour of sleep.

39. Arousals
 # of arousals = the total number of
arousals recorded during the
polysomnogram.
 Arousal index = the average number of
arousals per hour of sleep.
 <20 years is 10-20/hour
 50-60 years 20-22/hr

40. Technical impression
 The technical impression is the overall
breakdown and comments for the entire
polysomnogram.

41. Review of Sleep Study Times,
formulas and calculations:
 Sleep statistics – Lights Out – Light On –
Total Recording Time – Total Sleep Time
– Sleep Latency – Sleep Efficiency – Rem
Latency – WASO (wake after sleep onset)
– Time and percentage in each sleep
stage

42. Respiratory Events
 Number of obstructive apneas – Number
of mixed apneas – Number of central
apneas – Number of hypopneas –
Respiratory effort related arousals
(RERAs)

43. Oxygen saturation
 Baseline oxygen saturation (at the start of
the study)
 Lowest oxygen saturation during sleep

44. Diagnosis
 The diagnosis portion is where the diagnosis for
this polysomnogram are listed. The diagnosis of
Obstructive sleep apnea is based upon the RDI.
Mild RDI 5/hr. to 15/hr.
Moderate RDI 15/hr. to 30/hr.
Severe RDI >30/hr.
-Split Night Study:in patients with moderate to high
probabity of OSA at least 3 hours of Diagnostic
portion followed by atleast 4 hours for titration

45.  THANK YOU