Abstract P171: Optimizing Pre- and Post-defibrillation Pauses Improves the Likelihood of Return of Spontaneous Circulation
Background: The three-phase model of ventricular fibrillation (VF) arrest suggests a period of compressions to “prime” the heart prior to defibrillation attempts. In addition, post-shock compressions may be required to increase the likelihood of return of spontaneous circulation (ROSC). The optimal pre- and post-shock intervals remain unclear.
Objective: To define optimal pre- and post-defibrillation compression pauses for out-of-hospital cardiac arrest (OOHCA).
Methods: A convenience sample of patients suffering OOHCA from VF was included. Defibrillator data were abstracted and analyzed using the combination of ECG, impedance, and audio recording. Receiver-operator curve (ROC) analysis was used to define the optimal pre-and post-shock compression intervals. Multiple logistic regression analysis was used to quantify the relationship between these intervals and ROSC sustained to ED admission. Covariates included: cumulative number of defibrillation attempts, intubation status, and administration of epinephrine in the immediate pre-shock compression cycle. A separate set of regression models were run incorporating Utstein variables.
Results: A total of 36 patients with 96 defibrillation attempts were included. The ROC analysis identified an optimal pre-shock interval of <3 seconds and an optimal post-shock interval of <6 seconds. Increased likelihood of ROSC was observed with a pre-shock interval <3 seconds (adjusted OR 4.0, 95% CI 1.3–12.6, p=0.018) and a post-shock interval of <6 seconds (adjusted OR 4.1, 95% CI 1.1–15.0, p=0.034). Likelihood of ROSC was substantially increased with optimization of both pre- and post-shock intervals (adjusted OR 7.4, 95% CI 1.8 –29.6, p<0.01). Incorporating Utstein variables did not substantially change these results.
Conclusions: Decreasing pre- and post-shock compression pauses increases the likelihood of ROSC in OOHCA from VF.