Quantitative Sleep Monitoring - Quantitative EEG Analysis Methods and Clinical Applications - page 260

Table 10.2 Representative Changes in Sleep Architecture

Severe Sleep
Apnea 20-Year-Old 60-Year-Old

WASO% SPT 5 15 20

1% SPT 5 5 10

2% SPT 50 55 60

3 and 4% SPT 20 5 0

REM% SPT 25 20 10

Table 10.3 Montages for Sleep Monitoring

Bipolar Referential

Recording (Each
Against Reference
Electrode) Displays a Minimal Typical

C4-A1 (C3-A2) C4-A1 C4 C4-A1

ROC-A1 b

C3-A2 C3 C3-A2

LOC-A2 b O2-A1 O2 O1-A2

Chin EMG1-EMG2 O1-A2 O1 O2-A1

ROC-A1 ROC ROC-A1

LOC-A2 LOC LOC-A2

Chin EMG1-EMG2 A1 Chin

EMG1-EMG2

A2
EMG1
EMG2
EMG3

a

Any combination of referentially recorded electrodes can be displayed.

b

ROC = right outer canthus; LOC = left outer canthus.

erential recording). Any combination of various tracings of interest can be obtained
by digital subtraction (electrode A-reference) − (electrode B-reference) = electrode A

− electrode B either during recording or during review (see Table 10.3) [5, 6]. Digital

recording also allows for the mixture of referential (EEG, eye electrodes, EMG elec-
trodes), true bipolar (chest, abdominal movement, airflow), and dc (oxygen satura-
tion) recording.
The sampling rate must be more than twice the frequencies being recorded to
avoid signal distortion (aliasing). In addition, signals with a frequency higher than
one-half the sampling rate must be filtered out, because they can cause aliasing dis-
tortion [5].
Time windows of 60 to 240 seconds may be used to view and score respiratory
events. Alternatively, viewing data in 10-second windows (equivalent to 30 mm/s) is
the usual practice for viewing clinical EEG and displaying interictal or epileptic
activity. It also can be useful for measuring the frequency of a complex of oscilla-
tions or viewing the EKG.