CU-ER1 Operator’s Manual _ver 3.00
When the Defibrillation shock is delivered, current flow is affected by transthoracic
impedance, the body’s resistance from electrode to heart. Impedance is dependent on the
anatomy of the chest, skin surface, air in the chest, hair, fat and bone, as well as the size
and location of the defibrillation electrodes.
(ohms)
Resistance
lts)
Voltage(vo
ps)
Current(am
=
Research has shown that
chest resistance can vary significantly from patient to patient.
Patients with low impedance are generally easier to defibrillate because the flow of current
meets little resistance. Those with higher impedance may be more difficult to defibrillate.
According to the International Guidelines 2000 by the American Heart Association (AHA) in
collaboration with the International Liaison Committee On Resuscitation (ILCOR), average
adult impedance is 70-80 ohms. Defibrillation energy should be designed to optimize the
delivery of current over a wide range of patient impedances. Too much current to the
myocardial cells can cause damage to the cells and result in an unsuccessful defibrillation.
Too little current to the myocardial tissue cells will not depolarize the cells and result in an
unsuccessful defibrillation.
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