Actiheart User Manual 5.1.31 (Jun 2022)
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6.0 Sleep Analysis [Research Only]
6.1 Overview
The Actiheart for Sleep software can be used for analyses to aid the detection of
Obstructive Sleep Apnoea (OSA) and to identify the sleep stages.
Note that this
is an optional software module for research purposes only. It is not
verified or guaranteed in any manner and all results should be treated with
caution
. Because of this, the function must first be enabled by entering the
Utilities menu of the software and selecting the “Enable Sleep Analysis” check-
box.
Two techniques are utilised in the Actiheart for OSA screening. The first
1
) relies solely on the use of Heart Rate Variability (HRV) analysis.
This technique does not attempt to identify specific apnoeic episodes. The
second technique (
) attempts to pinpoint individual apnoeic
occurrences through the use of either HRV alone
2
or HRV combined with ECG
–
Derived Respiration
3
(EDR).
EDR is an indirect method of monitoring respiration. It is not as accurate as direct
methods that measure airflow directly. ECGs recorded from the surface of the
chest are influenced by the motion of the electrodes with respect to the heart due
to expansion and contraction of the chest during breathing. The ECG is also
affected by changes in the electrical impedance of the thoracic cavity due to the
filling and emptying of the lungs. These physical influences result in amplitude
variations in the ECG waveform which is inversely correlated with respiration, i.e
higher amplitude ECG corresponds to a lower EDR amplitude.
Sleep stage identification in the Actiheart employs HRV analysis based on the
findings of Vaughn
4
and others but also uses the movement data captured by the
accelerometer in the Actiheart. The algorithm used is described in more detail in
6.1.1 Choosing
an Application
for Making a
Recording
Any Actiheart 5 recording can be used for Sleep Analysis. If the user is
interested in conducting a sleep analysis, then it is easiest to set-up the Actiheart
from the ‘Sleep analysis’ screen to ensure an appropriate recording mode (even
if using earlier Actiheart or Actiwave devices).
1
See Frederic Roche et al., Cardiac Interbeat Interval Increment for the
Identification of Obstructive Sleep Apnoea, Journal of Pacing and Clinical
Electrophysiology, Vol. 25, No. 8, August 2002.
2
See Th. Penzel et al., Systematic comparison of different algorithms for apnoea
detection based on electrocardiogram recordings, Med. Biol. Eng. Comp., 40,
2002.
3
See George .B Moody et al., Derivation of Respiratory Signals from Multi-lead
ECGs, Computers in Cardiology, Vol. 12, 1985.
4
See B. V. Vaughn et al., Heart period variability in sleep,
Electroencephalography and Clinical Neurophysiology, 94, 1995.
