Conceptual models of coronary perfusion pressure and their relationship to defibrillation success in a porcine model of prolonged out-of-hospital cardiac arrest.

INTRODUCTION: The amount of myocardial perfusion required for successful defibrillation after cardiac arrest is unknown. Coronary perfusion pressure (CPP) is a surrogate for myocardial perfusion. One limited clinical study identifies a threshold of 15 mmHg required for return of spontaneous circulation (ROSC). Our exploration of threshold and dose models of CPP during the initial bout of CPR indicates higher levels than previously demonstrated are required. CPP required for shock success throughout on-going resuscitation is unknown and other conceptual models of CPP have not been explored. HYPOTHESIS: An array of conceptual models of CPP is associated with and predicts defibrillation success throughout resuscitation.
METHODS: Data from 6 porcine cardiac arrest studies were pooled. Mean and area under the curve (AUC) CPP were derived for 30-s epochs. Five conceptual models of CPP were analyzed: threshold, delta, cumulative delta, dose, and cumulative dose. Comparative statistics were performed with one-way ANOVA and two-tailed t-test. Regression models assessed CPP trends and prediction of ROSC.
RESULTS: For 316 defibrillation attempts in 124 animals, those resulting in ROSC (n=75) had significantly higher threshold, delta, cumulative delta, dose, and cumulative dose CPP than those without. All conceptual models except delta CPP had significantly different values across successive defibrillation attempts and all five models were significant predictors of ROSC, along with experimental design.
CONCLUSIONS: Threshold, delta, cumulative delta, dose, and cumulative dose CPP predict individual defibrillation success throughout resuscitation.