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Technical Data 8
User Guide Defibrillation pulse 8.3
Art. no.: 2.511279 Rev. d
FRED
®
easyport
®
plus
8.3.1 Shock Advisory System
The Shock Advisory System (SAS) validation test set consists of 17,803 ECG
waveforms coming from the PhysioNet databases [1]. These files (MIT-VFDB) are
subsets of the general PhysioNet databases recognised as standard in ECG tests.
PhysioNet databases are ECG Holter recordings with full diagnostic bandwidth [0.05
- 125] Hz. The bandwidth of the devices that recorded the signals is larger than that
of the FRED easyport plus. However, when the analogue signals of the database are
run on the FRED easyport plus via electrode connector, the FRED easyport plus's
rhythm detector signal-processing characteristics are applied. Moreover these
signals are of appropriate length to allow decisions to be made by the detector
system.
The validation test set database used to establish compliance with the AHA
requirements [2] and the IEC Standards [3] is used independently to develop the
rhythm recognition detector.
The SAS validation test set contains the following ECG samples (see test sample size
in Table 1):
• coarse ventricular fibrillation (VF) (>200 μV peak-to-peak amplitude)
• shockable ventricular tachycardia (VT hi) (HR >150 bpm, rushes that last more
than 8s)
• asystole (≤100 μV peak-to-peak amplitude)
• normal sinus rhythm (NSR) (PQRS-T waves visible, HR 40-100 bpm)
• other organized rhythm (N) (includes all rhythms except those in other listed cate-
gories)
For each test sample, in function of the expert rhythm annotation and the SAS
decision (shock/no shock), an interpretation table is built and shows the true positive
(correct classification of a shockable rhythm), true negative (correct classification of a
non-shockable rhythm), false positive (non-shockable rhythm incorrectly classified as
a shockable rhythm), false negative (shockable rhythm incorrectly classified as non-
shockable). Finally, the results of the detector performance are reported in terms of:
specificity-Sp (TN/(TN+FP)), true predictive value (TP/(TP + FP)), sensitivity-Se (TP/
(FN + TP)), false positive rate (FP/(FP + TN)).
Table 1: FRED easyport plus SAS performance by rhythm category meets AHA
recommendations [2] and IEC Standards [3] for adult defibrillation on artefacts-free
MIT-VFDB signals:
The FRED easyport plus SAS test has been completed with a validation database
consisting of 2,475 couples of ECGs and transthoracic Impedance Cardiogram (ICG)
from out-of-hospital cardiac arrest (OHCA) interventions, recorded with Automated
External Defibrillators (FredEasy, Schiller Medical SAS, France) used by the fire
brigade of Paris.
This supplementary test completes the validation of the SAS and achieves the results
summarised in table 1. A report of the global validation test results is available on
request.
Rhythms
Test sample
size
Performance goal
Observed perfor-
mance
[1]: The MIT-BIH Malignant Ventricular Arrhythmia
Database
http://physionet.org/physiobank/database/vfdb/
[2]: Automatic External Defibrillators for Public Ac-
cess Defibrillation : Recommendations for Specify-
ing and Reporting Arrhythmia Analysis Algorithm
Performance, Incorporating New Waveforms and
Enhancing Safety ; Circulation, 1997 ; 95 :1677-
1682.
[3]: Standard IEC 2010 60601-2-4, ed 3.
Shockable Coarse VF 308 Sensitivity > 90% Meets [2-3]
VT hi 202 Specificity > 75% Meets [2-3]
Non Shockable NSR 1023 Sensitivity > 99% Meets [2-3]
Asystole 4798 Sensitivity > 95% Meets [2-3]
Other rhythms 1425 Sensitivity > 95% Meets [2-3]
Total NS 7246 Sensitivity > 95% Meets [3]
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