38
Defibrillation
Defibrillation waveform
Waveform
parameters
Waveform parameters are automatically adjusted as a
function of patient defibrillation impedance. In the diagram at
left, A is the width of pulse 1 and B is the width of pulse 2 of
the waveform, C is the inter-pulse delay, I
p
is the peak current,
and I
f
the final current.
The AED delivers shocks to load impedances from 25 to 175
ohms. The duration of each pulse of the waveform is
dynamically adjusted based on delivered charge, in order to
compensate for patient impedance variations, as shown
below:
Adult defibrillation
Load
Resistance (
Ω
)
Pulse width 1
(ms)
Pulse width 2
(ms)
Delivered
Energy (J)
25 3.3 3.1
195
50 4.7 4.1
190
75 6.7 4.7
185
100 8.3 5.9
195
125 9.7 6.7
190
150 11.3 7.9 185
175 11.7 8.7 180
Pediatric defibrillation
Load
Resistance (
Ω
)
Pulse width 1
(ms)
Pulse width 2
(ms)
Delivered
Energy (J)
25 3.3 3.1
51
50 4.7 4.1
50
75 6.7 4.7
49
100 8.3 5.9 51
125 9.7 6.7 50
150 11.3 7.9 49
175 11.7 8.7 47
Charge control
Controlled by patient analysis system for automated
operation.
Charging Time
< 10 seconds typical
Shock Analysis
Time
8 to 13 seconds
