Coronary Perfusion Pressure and Return of Spontaneous Circulation after Prolonged Cardiac Arrest

INTRODUCTION: The amount of myocardial perfusion required for successful defibrillation after prolonged cardiac arrest is not known. Coronary perfusion pressure (CPP) is a surrogate for myocardial perfusion. One limited clinical study reported that a threshold of 15 mmHg was necessary for return of spontaneous circulation (ROSC), and that CPP was predictive of ROSC. A distinction between threshold and dose of CPP has not been reported. OBJECTIVE: To test the hypothesis that swine achieving ROSC will have higher preshock mean CPP and higher preshock area under the CPP curve (AUC) than swine not attaining ROSC. METHODS: Data from four similar swine cardiac arrest studies were retrospectively pooled. Animals had undergone 8-11 minutes of untreated ventricular fibrillation, 2 minutes of mechanical cardiopulmonary resuscitation (CPR), administration of drugs, and 3 more minutes of CPR prior to the first shock. Mean CPP +/- standard error of the mean (SEM) was derived from the last 20 compressions of each 30-second epoch of CPR and compared between ROSC/no-ROSC groups by repeated-measures analysis of variance (RM-ANOVA). AUC for all compressions delivered over the 5 minutes was calculated by direct summation and compared by Kruskal-Wallis test. Prediction of ROSC was assessed by logistic regression. RESULTS: Throughout the first 5 minutes of CPR (n = 80), mean CPP +/- SEM was consistently higher in animals with ROSC (n = 63) (maximum CPP 41.2 +/- 0.6 mmHg) than animals with no ROSC (maximum CPP 20.1 +/- 0.3 mmHg) (p = 0.0001). Animals with ROSC received more total reperfusion (43.9 +/- 17.6 mmHg x 10(2)) than animals without ROSC (21.4 +/- 13.7 mmHg x 10(2)) (p < 0.001). Two regression models identified CPP (odds ratio [OR] 1.11; 95% confidence interval [CI] 1.05, 1.18) and AUC (OR 1.10; 95% CI 1.05, 1.16) as predictors of ROSC. Experimental study also predicted ROSC in each model (OR 1.70; 95% CI 1.15, 2.50; and OR 1.59; 95% CI 1.12, 2.25, respectively). CONCLUSION: Higher CPP threshold and dose are associated with and predictive of ROSC.