Comparison of paddle electrode pastes used for defibrillation

The transthoracic impedance to direct-current defibrillator discharge of several defibrillator paddle electrode-skin interfaces has been reported from this laboratory. The interface that offers the lowest impedance to defibrillator discharge is Redux paste. This study compares the transthoracic impedance to direct-current defibrillation discharge of recently marketed defibrillator electrode paste (cardiac defibrillator cups) and Redux paste. Eight dogs, weighing 23.0±6.5 kilograms, were used. They were shocked at a defibrillator meter setting of 100 watt-seconds (mean delivered energy of 62 watt-seconds). Each animal received a total of 12 shocks with both pastes. The sequence of shocks was changed in alternate animals. The mean impedance to defibrillator discharge using the cardiac defibrillator cups was 61.2±5.6 ohms compared to 46.8±4.5 ohms using the Redux paste (p<0.01). The output of some defibrillators in use today is inadequate for consistent defibrillation of adult patients weighing more than 50 to 80 kilograms. Since a minimal peak current per kilogram of body weight is required for ventricular defibrillation and since a higher transthoracic impedance results in a lower delivered peak current, one should use the paddle electrode-chest wall interface that results in the lowest impedance to defibrillator discharge. The impedance encountered with the cardiac defibrillator cups is significantly higher than that with the Redux paste. Therefore, the authors do not recommend the use of the cardiac defibrillator cups for defibrillation or elective cardioversion.