User Manual

LIFEPAK CR Plus and LIFEPAK EXPRESS Defibrillator Operating Instructions B-1
©2009-2010 Physio-Control, Inc.
Appendixes
Shock Advisory System
OVERVIEW OF THE SHOCK ADVISORY SYSTEM
The Shock Advisory System (SAS) is an ECG analysis system built into the LIFEPAK CR Plus and
LIFEPAK EXPRESS defibrillators that advises the operator if it detects a shockable or nonshockable
rhythm. This system makes it possible for individuals not trained to interpret ECG rhythms to provide
potentially-lifesaving therapy to victims of ventricular fibrillation or pulseless ventricular tachycardia. The
SAS contains the following features:
• Electrode contact determination
• Automated interpretation of the ECG
• Operator control of shock therapy
• Motion detection
Electrode Contact Determination
The victim's transthoracic impedance is measured through the defibrillation electrodes. If the baseline
impedance is higher than a maximum limit, it is determined that the electrodes are not in sufficient
contact with the victim or not properly connected to the defibrillator. ECG analysis and shock delivery
are inhibited. The operator is advised to connect electrodes any time electrode contact is inadequate.
Automated Interpretation of the ECG
The Shock Advisory System is designed to recommend a shock if it detects the following:
•
Ventricular fibrillation — with a peak-to-peak amplitude of at least 0.08 mV
•
Ventricular tachycardia — defined as having a heart rate of at least 120 beats per minute, QRS
width of at least 0.16 seconds, and no apparent P waves.
Pacemaker pulses may prevent advisement of an appropriate shock, regardless of the victim’s
underlying rhythm. The SAS is designed to recommend no shock for all other ECG rhythms including
pulseless electrical activity, idioventricular rhythms, bradycardia, supraventricular tachycardias, and
normal sinus rhythms.
ECG analysis is performed on consecutive 2.7 second segments of ECG. The analysis of two out of
three segments must agree before a decision (
SHOCK ADVISED or NO SHOCK ADVISED) is made.
The LIFEPAK CR Plus and LIFEPAK EXPRESS defibrillator SAS performance for adult, pacemaker and
pediatric ECGs is summarized in the following table.
Table B-1 LIFEPAK CR Plus and LIFEPAK EXPRESS Defibrillator SAS Performance Table for Adult ECGs
Rhythm Class
ECG Test
1
Sample Size
Performance Goal
2, 3
Observed Performance
Sensitivity or Specificity [LCL]
4
Shockable:
coarse VF
168 >90% sensitivity 100.0% [98.6%]
Shockable:
shockable VT
65 >75% sensitivity 84.6% [77.3%]
Nonshockable:
NSR
144 >99% specificity for
NSR (AHA)
100.0% [98.4%]
Nonshockable:
asystole
43 >95% specificity 100.0% [94.8%]