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Introduction

This article describes how to activate the optional setting of the ECG quality display and how the system display the current ECG quality. 

General

In rehab, the ECG signal is evaluated for its quality. The program analyses the signal quality separately for each ECG channel and assigns one of the following signal qualities every second:

ECG signal qualityExample ECG signalScore value in information blockDescription
good ECG quality

E:1ECG must look like this, with such an ECG signal there are guaranteed no problems with the QRS detection
sufficient ECG quality

E:3This ECG quality means that the QRS detection will still recognize every QRS complex due to internal filtering, but it is already an indication that one or the other QRS complex may be overlooked here.
insufficient ECG quality

E:6This ECG quality means that the QRS detection is certainly "overlooked" despite the internal filtering of some QRS complexes (false negative) or disturbances of the ECG signal even as QRS detection (false positive).
non-physiological ECG quality

E: !!With such an ECG Signal no QRS complex can be detected. This occurs, for example, when the electrodes of the ECG conduction are open.


The ECG signal quality information is used for the following actions/displays

  • automatic switching off of the ECG display on the overview page
  • QRS detection
  • optical alarm in case of very poor ECG signal quality
  • numeric output in the info block
    - as score value
    - as a numerical value (which is of a technical nature)
    - as a statistical entry in the evaluation display 


Setting for the ECG quality display

The visibilty of ECG signal quality can be activated in Option 4.13 under  Settings → Reha → General → Menu/Functions → Additional settings for exercise stations → Display options in the exercise.

                   


In case of a bad ECG signal quality a transparent red square is fade in over the ECG in the online ECG part. With a 3 channel ECG the rectangle is vertically divided into three equal areas. One for each channel. This allows the quality of all three channels to be signalled simultaneously even if the currently displayed ECG channel is not affected.


Display of ECG signal quality

The ECG quality is dispalyed 

  • in online ECG view on the owervie page of rehab training 
  • as score value in any Info block 

ECG signal quality dispaly in online ECG view

As long as the ECG has a good quality, no display in online ECG appears on the overview page. In case of insufficient ECG quality, a transparent red rectangle appears on the right side of the online ECG. Depending on the number of ECG channels, either one or three colored rectangles are displayed.

1 channel ECG

In this case, one ECG channel has a insufficient on quality
3 channel ECG

In this case the 1st ECG channel is displayed and channels 2 and 3 are of poor quality.
This can be seen from the slightly bolder representation of the channel designation I. If a single-channel ECG display is activated (and only then), channel occupancy of the current ECG channel is highlighted so that you can see which of the ECG channels are of bad or good quality, even if they are not currently displayed.
In this case, the displayed ECG channel 1 is of good quality, but the other two ECG channels (these are currently blanked out) are of insufficient quality.


The display of the ECG quality disappears automatically if this is OK.


Numerical display of ECG quality

In contrast to the graphic quality display, the numerical displays are always retained, even if the ECG is of good quality. 

As score value

Any information block can be configured to display the ECG quality score value

1 channel ECG


The ECG channel has a quality score of 6, which means insufficient ECG quality.
3 channel ECG

In this three-channel ECG display, the ECG channel 1 is of poor quality (score vauel of 6) and the other two channels are not physiological (score value of 20). 


As numerical vaue

The determination of the ECG signal quality has as result a numerical value, which can be interpreted as a measure of the noise. This can be displayed as a single numerical value for each channel. The value itself is more of a technical specification and should therefore only be displayed in disputed quality cases. 

1 channel ECG

The ECG channel has a quality vaue of 5.6
3 channel ECG

ECG channel 1 has a quality vaue of 5.6 wich is good ECG, the other channels (value around 14) are close to the unphysiological signal






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