Abstract Su302: Impact of Time to Defibrillation on Mortality after In-Hospital Cardiac Arrest

Abstract

Background: In-hospital cardiac arrest occurs in 290,000 patients annually in the United States, with less than 20% of these arrests featuring a shockable presenting rhythm. The three-phase model of CPR is separated into the electrical phase which occurs in the first 4 minutes, the circulatory phase which includes minutes 4-10, and the metabolic phase which is greater than 10 minutes from arrest onset. Defibrillation during the electrical phase has been proven to improve survival by approximately 50%. Current guidelines recommend defibrillation within the first 2 minutes of arrest in those with a rhythm of VT/VF. The purpose of this study was to determine the effect of time to defibrillation on mortality in patients with shockable rhythms. Methods: Full-disclosure rhythm strips for all cardiac arrests in non-ICU patients on telemetry were reviewed from Feb 2019 to April 2023. Time to defibrillation of shockable rhythms (VT/VF) was determined from the telemetry data and corresponding defibrillator data from the Zoll CodeNet electronic system. Results: We identified 32 of the 186 patients with cardiac arrest while on telemetry presenting with pulseless monomorphic VTor polymorphic VT/VF. The average time to defibrillation was 4.8 min ± 2.7 min. 34% of patients were defibrillated in 4 minutes or less from the onset of the arrythmia, 31% were defibrillated in more than 4 minutes from the onset of the arrythmia, and 34% were not defibrillated. Patients defibrillated in 4 minutes or less had a significantly lower mortality of 36.4% compared to a 50% mortality of those defibrillated in more than 4 minutes and 90.9% mortality in those not defibrillated (p<0.05).The patients who were not defibrillated were determined to have ongoing VT or poly VT/VF until telemetry was removed and the Zoll defibrillator pads were applied. They were ultimately deermined ot have PEA and were not shocked. Conclusions: Patients defibrillated in 4 minutes or less from the onset of a sustained shockable arrythmia experienced significantly lower mortality during hospitalization compared to those who were defibrillated in more than 4 minutes or were not defibrillated. 34% of patients with a shockable rhythm were not defibrillated due to a diagnosis of PEA after the Zoll pads were placed. Patients with sustained VT/VF causing in-hospital cardiac arrest should be defibrillated as soon as a defibrillator can be applied. Telemetry data should be clearly communicated to the code team.