Physio-Control LIFEPAK 20e - Manual (Page 191)

Append
ix E
Shock Advisory System
LIFEPAK 20e Defibrillator/Monitor Operating Instructions E-1
©2006-2013 Physio-Control, Inc.
OVERVIEW OF THE SHOCK ADVISORY SYSTEM
The Shock Advisory System™ (SAS) is an ECG analysis system built into the LIFEPAK 20e
defibrillator/monitor that advises the operator as to whether it detects a shockable or
nonshockable rhythm. This system makes it possible for individuals who are not trained to
interpret ECG rhythms to provide potentially lifesaving therapy to victims of ventricular fibrillation
or pulseless ventricular tachycardia. The Shock Advisory System contains the following features:
• Electrode Contact Determination
• Automated Interpretation of the ECG
• Operator Control of Shock Therapy
• Continuous Patient Surveillance System (CPSS)
• Motion Detection
The Shock Advisory System is active when the LIFEPAK 20e defibrillator/monitor is used as an
automated external defibrillator (AED). CPSS may be activated during monitoring.
Electrode Contact Determination
The Shock Advisory System measures the patient's transthoracic impedance through the
therapy electrodes. If the baseline impedance is higher than a maximum limit, it determines that
the electrodes do not have sufficient contact with the patient or are not properly connected to the
AED. When this occurs, ECG analysis and shock delivery are inhibited. The AED advises the
operator to connect electrodes when there is insufficient electrode contact.
Automated Interpretation of the ECG
The Shock Advisory System recommends 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 patient’s
underlying rhythm. The Shock Advisory System recommends no shock for all other ECG rhythms
including asystole, pulseless electrical activity, idioventricular rhythms, bradycardia,
supraventricular tachycardias, atrial fibrillation and flutter, heart block, premature ventricular
complexes and normal sinus rhythm. These rhythms are specifically mentioned in the AHA
recommendations.
Shock Advisory System Performance
ECG analysis by the Shock Advisory System (SAS) in the LIFEPAK 20e defibrillator/monitor
(AED) series was tested by playing ECG waveforms from the Physio-Control database through
the electrode connector. For each test ECG, the decision (shock or no shock) of the SAS was
recorded and compared to the rhythm classification and treatment recommendation by clinical
experts.
SAS Test Set
The SAS Test Set consists of 989 ECG samples recorded through defibrillation electrodes during
pre-hospital use of the LIFEPAK 5 defibrillators. The defibrillation electrodes and ECG signal
processing were similar to those used in the LIFEPAK 20e defibrillator/monitor. The ECG was
recorded using cassette tape recorders connected to the LIFEPAK 5 defibrillators. Selected ECG
segments were sampled and the ECG rhythm was classified by clinical experts. The rhythms