ZOLL M Series Defibrillator Rev YH - Manual (Page 22)

M S ERIES O PERATOR ’ S G UIDE
1-14
ECG Analysis Algorithm Accuracy
Sensitivity, specificity, false positive rate and positive predictivity are expressions of the accuracy of an ECG analysis
system when compared with clinicians or experts. The specifics of computations are detailed below. The
accompanying data details the accuracy of the algorithm as tested by independent investigators.
The Algorithm:
• Divides the ECG rhythm into three 3-second segments.
• Filters and measures noise, artifact, and baseline wander.
• Measures baseline content ('waviness' at the correct frequencies- frequency domain analysis) of signal.
• Measures QRS rate, width, and variability.
• Measures amplitude and temporal regularity ('auto-correlation') of peaks and troughs.
• Determines if two-out of-three, 3 second segments are shockable then displays “SHOCK ADVISED” message.
The Algorithm sequence takes approximately 9 seconds.
Clinical Performance Results
Applications: # of analyses # of patients
316 194
Shockable Rhythm
Overall Sensitivity 95.7%
Positive Predictability100.0%
Non-shockable Rhythm
Overall Sensitivity 100%
False Positive Rate 0%
Sensitivity = # of “correct shock” decisions by algorithm
Total # of rhythms for which a shock is clinically advised
Specificity = # of “correct no shock” decisions by algorithm
Total # of rhythms for which no shock is clinically advised
False Positive Rate = # of “incorrect shock” decisions by algorithm
Total # of rhythms for which no shock is clinically advised
Positive Predictivity = # of “correct shock” decisions by algorithm
Total # of rhythms for which shock is advised by unit