Spacelabs Healthcare 98000, Operation Manual

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070-2567-03 Rev. A
18-11
18.15 Review Options
If the Bazett correction value is set to zero, the previous valid RR interval will be used to calculate
QTc. This is the default setting and applicable for recordings with stable or resting heart rates.
Any changes to this value should be noted when reporting QTc.
Report Averaging Length: A running average filter applied to the sequences of valid values before
determining the maximum, minimum and standard deviation values reported in the report
summary and tables.
Threshold Levels: Intervals over the user defined thresholds are reported as a % over.
QT / RR Ratio, NN Filter: A setting for the variability ratio measurement. The default is to have
this activated.
This ratio is calculated as standard-deviation (QT) / standard-deviation NN.
There is an option “Apply NN Filter”: If it is set the filter is used, otherwise all the NN are
included.
The filter is as follows:
Diff(i) = NN(i) - 0.25*(NN(i-2) + NN(i-1) + NN(i+1) + NN(i+2))
If Diff(i) > 25% NN(i), then exclude NN(i) from the standard-deviation (NN) calculation