ZOLL X Series Monitor Defibrillator Rev H - Manual (Page 321)

ECG Analysis Algorithm Accuracy
9650-001355-01 Rev. H X Series Operator’s Guide A-35
ECG Analysis Algorithm Accuracy
Sensitivity and specificity are expressions of ECG analysis algorithm performance when compared to
ECG interpretation by a clinician or expert. Sensitivity refers to the algorithm’s ability to correctly
identify shockable rhythms (as a percentage of the total number of shockable rhythms). Specificity
refers to the algorithm’s ability to correctly identify non-shockable rhythms (as a percentage of the
total number of non-shockable rhythms). The data in the following table summarizes the accuracy of
the ECG analysis algorithm as tested against ZOLL’s ECG Rhythm Database.
The algorithm sequence takes approximately 9 seconds and proceeds as follows:
• Divides the ECG rhythm into three-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 multiple 3 second segments are shockable then displays SHOCK ADVISED
message.
Clinical Performance Results
The performance of the incorporated analysis algorithm in a single analysis sequence satisfies the
applicable requirements specified in ANSI/AAMI DF80 (section 6.8.3) and the recommendations by
Kerber et al. (Circulation. 1997;95(6):1677).
Table A-4. Clinical Performance Results
References:
Young KD, Lewis RJ: “What is confidence? Part 2: Detailed definition and determination of
confidence intervals”. Annals of Emergency Medicine, September 1997; 30; 311-218
William H. Beyer, Ph.D.: “CRC Standard Mathematical Tables 28
th
Edition,” CRC Press, Inc, Boca
Raton, FL., 1981, Percentage Points, F-Distribution Table, pg 573.
Rhythms Sample
Size Performance Goals Observed
Performance
90% One-sided
Lower Confidence
Limit
Shockable Sensitivity
Coarse VF
Rapid VT
536
80
>90%
>75%
>99%
>99%
>99%
>96%
Non-shockable Specificity
NSR
AF, SB, SVT, Heart block,
idioventricular, PVCs
Asystole
2210
819
115
>99%
>95%
>95%
>99%
>99%
>99%
>99%
>99%
>97%
Intermediate
Fine VF
Other VT
69
28
Report only
Report only
Sensitivity
>89%
>96%
>81%
>84%