LIFEPAK 15 Monitor/Defibrillator
Service Manual
Device Description
Functional Descriptions
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Dump relay control
A fail-safe system used to safely dissipate defibrillation energies from the energy storage capacitor under a number of
circumstances (for example, change of energy selection, power removal, pacing activation, and QUIK-COMBO leads-off).
With the exception of power removal, the dump relay control system functions under the control of the system and/or
defibrillator processors.
QUIK-COMBO leads-off (impedance sense/motion detection)
With the QUIK-COMBO electrodes applied and the device in AED mode, leads-off/motion detection circuits are active. Only
leads-off is active when device is in Manual mode and QUIK-COMBO electrodes applied.
For purposes of this discussion, consider the leads-off/motion detector and patient system as a simple voltage divider.
Leads-off/motion detection relies on two main characteristics:
~ Leads-off/motion detector output impedance is relatively high (greater than 125 k
~ Patient impedance is relatively low (typically less than 30
).
To exploit these characteristics, the device injects an ac impedance drive signal through the QUIK-COMBO electrodes into
the relatively low patient impedance and monitors the voltage drop across the patient. Minute perturbations sensed in the
low-amplitude signal developed across the patient represent motion; gross changes in the sensed signal indicate electrode
disconnection.
Paddles/QUIK-COMBO ECG preamplifier
The ECG paddles/QUIK-COMBO ECG preamplifier perform the functions of patient isolation, electrostatic discharge and
defibrillation protection, baseline dc restore, bandwidth filtering, internal pacemaker detection, and ECG sampling through
analog-to-digital conversion (ADC). Results from the ADC process are fed to the paddles/pacer processor.
