Study objectives: Time to defibrillation is the most important factor affecting survival from cardiac arrest. Mortality increases by approximately 7% to 10% for each minute that defibrillation is delayed. Therefore, any improvement in time to defibrillation could have an important impact on clinical survival. Valuable progress in shortening the inhospital “chain of survival” has been achieved with the development of cardiac monitored beds, dedicated cardiac arrest teams, and strategic location of defibrillators throughout the hospital. However, the specific impact of defibrillator electrodes on time to defibrillation has not been analyzed. The purpose of this study is to determine whether the choice of defibrillator electrodes affects the time to defibrillation.

Methods: This was a randomized crossover design study. It was approved by the institutional review board. Internal medicine and emergency resident physicians supervise cardiac arrest teams at many teaching hospitals, so they were selected to test this equipment. The residents were blinded to the intent of the study. We compared the time required by the residents to apply to the patient, then connect to a defibrillator, and then deliver a shock for 2 leading defibrillator electrodes, the Quik-Combo (Medtronic Physio-Control, Redmond, WA) and the Padpro (model 2516 Padpro LLC, Ann Arbor, MI). Under scripted direction of advanced cardiac life support–trained research nurses, they used the equipment during a standardized ventricular fibrillation cardiac arrest model using cardiopulmonary resuscitation mannequins. The independent variable was the choice of defibrillator electrode. Sequence of testing for the electrodes was block randomized to control for the confounding variable of learning. The primary outcome was time to defibrillation (total time elapsed from the beginning of cardiac arrest to delivery of a defibrillatory shock). The secondary outcome was the ease of application as assessed by the resident physicians with a 10-cm visual analog scale. The minimum required sample size was calculated to be 26 trials for each defibrillator electrode study group, assuming a 20% treatment effect between models (2-sided, for ⍺=0.05 and β=0.2). Statistical significance was analyzed using Student's t test for continuous variables.

Results: Thirty residents performed a crossover assessment of both electrodes. The average time to defibrillation for the Padpro was approximately double that of the Quik-Combo (88.2 seconds versus 44.5 seconds, P<.0001, 95% confidence interval [CI] of mean difference 23.4 to 63.9 seconds). As evaluated by the resident physicians on a 10-cm visual analog scale, the Quik-Combo was clinically and statistically significantly easier to apply than the Padpro (1.25 cm versus 4.76 cm, P<.0001; 95% CI of mean difference 1.91 to 5.12 cm).

Conclusion: The Quik-Combo defibrillator electrode significantly decreased the time to defibrillation and was judged to be easier to apply in this cardiac arrest model. The average time to defibrillation difference of 44 seconds when extrapolated to the clinical setting has important implications for patient survival and morbidity. International guidelines endorse a goal time of only 2 to 4 minutes from collapse until defibrillation. We demonstrate that the choice of defibrillator electrodes can significantly influence accomplishment of that goal. Cardiopulmonary resuscitation is a complex team task under highly stressful conditions. Regularly training on standardized equipment is essential for efficient cardiac arrest team performance. Hospital and emergency medical services authorities should select the most reliable and ergonomically simple equipment to minimize any delays in defibrillation.