Polysomnography is a diagnostic test that uses multiple sensors to evaluate sleep disorders. It measures brain waves, eye movements, muscle activity, heart rate, oxygen levels, and breathing during sleep. Key components include sleep EEG to analyze brain waves and identify sleep stages, respiratory monitoring to detect events like apnea, and oximetry to measure oxygen saturation. Pediatric polysomnography uses some modified techniques and sleep stage scoring criteria tailored for children.

1. Polysomnography
Dr. Kaustubh Mohite

2. Topics of
Discussion:
• What is Polysomnography ?
• Components of Polysomnography.
• Sleep EEG
• Respiratory events
• Sleep scoring

3. Polysomnography:
An elaborate diagnostic test composed of numerous data-collecting sensors working
concomitantly to aid in the evaluation of varied sleep disorders in all age groups.
Polysomnograph
Polysomnogram

4. Brief History:
Richard Caton. (1875) Pioneer who developed
a method for recording electrical impulses from the
surface of brains in animals.
Hans Berger. (1929) He made the first recording of
electrical activity of the human brain.

5. Nathaniel Kleitman, Established one of the foremost laboratories for the study of
sleep at the University of Chicago, where full-night sleep studies allowed the
discovery of rapid eye movement sleep
William Dement. (1957) He participated in the
discovery and description of the human sleep cycle
and started the first sleep clinic at Stanford University.

6. Indication of
Polysomnography:
• Obstructive sleep apnea syndromes
• Central sleep apnea, periodic breathing & Hypoventilation
syndromes
• Neuro-muscular disorders
• Chronic lung disease
• CPAP / BiPAP titration studies
• Tracheostomy decannulation
• Parasomnias
• Restless leg syndrome / Periodic limb movement disorders

7. Components of
Level 1 pediatric study

8. Sleep EEG
• AASM recommends electroencephalography (EEG) monitoring with
the following derivations: F4-M1, C4-M1, and O2-M1 with the
contralateral leads (F3-M2, C3-M2, O1-M2) additionally applied for
redundancy in the event of electrode failure.

9. Normal Sleep EEG waves:

13. So now let us analyze a 30 sec epoch of sleep EEG of a 8 year old child
Wakefulness – a clear posterior dominant rhythm seen in the occipital leads (arrow)
with erratic eye movements and blinks visualized in the EOG with high chin EMG signal.

14. N1 Sleep – low amplitude, high frequency waves

15. N2 Sleep – sleep spindles (left arrow) and K-complexes (right arrow) predominate the
record with < 20% of the record comprised of delta waves.

16. N3 Sleep – diffuse high-voltage delta wave slowing, comprising > 20% of the record.

17. REM Sleep – numerous rapid eye movements noted in EOG
with significant drop in chin EMG signal.

18. Respiratory events:

20. Obstructive Apnea

21. Central Apnea

22. Obstructive Hypopnea

23. Obstructive Apnea

24. EMG:
• Two surface electrodes are placed
either on the mentalis or submentalis
to detect muscle activity.
• As infants and young children have
smaller heads than adults, chin
electromyogram electrodes may need
to be placed 1 cm apart, rather than 2
cm apart as in adults.

25. Respiratory efforts:
• Respiratory and Abdominal inductance
plethysmography (RIP) is the preferred method.
• They help in differentiating obstructive from central
apneas.
• Oesophageal pressure monitoring is rarely used, as it is
invasive, and the nasal pressure flow signal is often
used as a surrogate when the upper airway resistance
syndrome is suspected.

26. Nasal – oral airflow:
• Airflow is measured by the oronasal thermal air
sensor and nasal pressure cannula.
• The thermistor is the recommended sensor for
apnoea detection.
• Nasal pressure cannula is a reasonable
alternative to oesophageal pressure monitoring.
• It captures airflow and is connected to a
pressure transducer to generate a signal, which
correlates with the size of breath and airflow
resistance.
• It is the recommended signal for hypopnoea
detection.

27. Oxygen
saturation:
• The sensor is incorporated into a soft
cuff that fits around a finger or toe or
clips to an ear lobe.
• Children tend to move frequently
during sleep, so the monitoring of the
pulse waveform in addition to the
saturation value is helpful in
distinguishing motion artefacts from
true desaturation.

28. CO2
monitoring:
Measurements of carbon
dioxide have been used in two
contexts during PSG:
• PETCO2 waveform as an
indicator of airflow
obstruction and, hence,
apnoea
• Measurement of PETCO2 or
PtcCO2 as a quantitative
measure of hypoventilation
during sleep

30. Pediatric sleep staging for
children(AASM 2.6)

31. I. Age for which these sleep stages are
applied
These rules are
applied for children
more than 2 months
post – term or older.
For infants less than
2 months post – term
there are separate
rules for infants.

32. II. Technical specifications:
• Adult electrode derivatives for EEG, EOG and chin EMG are acceptable for
recording pediatric sleep studies.
• However, the distance between the electrodes needs to be reduced:
• EMG leads to be placed 1 cm apart as compared to 2 cm in adults.
• EOG electrodes to be placed 0.5 cm from the eyes compared to 1 cm in
adults.

33. III. General scoring of sleep stages:
• Children above 2 months to be scored according to the following stages:
1. Stage W (wakefullness)
2. Stage N1 (NREM 1)
3. Stage N2 (NREM 2)
4. Stage N3 (NREM 3)
5. Stage R (REM)

34. 1. If all epochs of NREM sleep contain no recognizable sleep spindles, K complexes or
high-amplitude 0.5-2 Hz slow wave activity, score all epochs as stage N (NREM).
2. If some epochs of NREM sleep contain sleep spindles or K complexes, score those as
stage N2 (NREM 2).
3. If some epochs of NREM sleep contain greater than 20% slow wave activity, score
these as stage N3 (NREM 3). If in the remaining NREM epochs, there are no K
complexes or spindles then score as stage N (NRENN).
4. If NREM is sufficiently developed that some epochs contain sleep spindles or K
complexes and other epochs contain enough slow wave activity, then score NREM
sleep in this infant as either stage N1, N2 or N3 as in an older child or adult.

35. IV. Scoring stage W:
1. Following definitions are used in stage W:
• Eye Blink (0.5 – 2 Hz waves)
• Reading eye movements (trains of conjugate eye movement having a slow and a
fast component)
• Rapid eye movement (REM)(EOG showing conjugate, irregular, sharply peaked
eye movements lasting < 0.5 sec)
• Posterior dominant rhythm (PDR) (dominant reactive EEG rhythm over occipital
regions in state of wakefulness with eyes closed having frequency ranging from
3.5 Hz – 10 Hz)

36. Initial age of
waveform
appearance:
Waveform Age of initial
appearance
Sleep spindles 6 weeks – 3 months
post-term
K complexes 3 – 6 months post-term
Slow wave activity 2 – 5 months post-term
Vertex sharp
waves
4 – 6 months post-term
Hypnogogic
hypersynchrony
3 – 6 months

37. V. Scoring stage N1:
Following definitions are used in NREM 1:
• Slow eye movement (SEM): EOG deflection lasting > 0.5 sec. Seen in both eyes closed
wake phase and N1.
• Low-amplitude, mixed-frequency (LAMF) activity: 4 – 7 Hz activity.
• Vertex shaped waves (V waves): last < 0.5 sec. Appear first at 4 – 6 months post-term.
• Sleep onset.
• Hypnogogic hypersynchrony: paroxysmal bursts of diffuse, high-amplitude, sinusoidal
75 – 350 microvolts, 3 – 4.5 Hz waves. Occur in both N1 & N2.

38. Scoring stage N2:
• Sleep Spindles: 10 – 12.75 Hz over frontal and 12.5 – 14.75 Hz over central or
centroparietal region.
• K complex: Present after 5 – 6 months post-term and are maximal over pre-
frontal and frontal region.

39. Scoring stage N3:
• Slow wave activity in children are often of high amplitude (100 – 400
microvolts), 0.5 – 2 Hz activity, maximal over frontal region as early as 2
months, more often 3 – 4.5 months post-term

40. Scoring stage R:
• Continuous, low-amplitude, mixed-frequency EEG activity.