Cardiac Arrest Induced by Asphyxia Versus Ventricular Fibrillation Elicits Comparable Early Changes in Cytokine Levels in the Rat Brain, Heart, and Serum

BACKGROUND: Current postresuscitative care after cardiac arrest (CA) does not address the cause of CA. We previously reported that asphyxial CA (ACA) and ventricular fibrillation CA ( VFCA) elicit unique injury signatures. We hypothesized that the early cytokine profiles of the serum, heart, and brain differ in response to ACA versus VFCA. METHODS AND RESULTS: Adult male rats were subjected to 10 minutes of either ACA or VFCA. Naives and shams (anesthesia and surgery without CA) served as controls (n=12/group). Asphyxiation produced an similar to 4-minute period of progressive hypoxemia followed by a no-flow duration of similar to 6 +/- 1 minute. Ventricular fibrillation immediately induced no flow. Return of spontaneous circulation was achieved earlier after ACA compared with VFCA (42 +/- 18 versus 105 +/- 22 seconds; P<0.001). Brain cytokines in naives were, in general, low or undetectable. Shams exhibited a modest effect on select cytokines. Both ACA and VFCA resulted in robust cytokine responses in serum, heart, and brain at 3 hours. Significant regional differences pinpointed the striatum as a key location of neuroinflammation. No significant differences in cytokines, neuron-specific enolase, S100b, and troponin T were observed across CA models. CONCLUSIONS: Both models of CA resulted in marked systemic, heart, and brain cytokine responses, with similar degrees of change across the 2 CA insults. Changes in cytokine levels after CA were most pronounced in the striatum compared with other brain regions. These collective observations suggest that the amplitude of the changes in cytokine levels after ACA versus VFCA may not mediate the differences in secondary injuries between these 2 CA phenotypes.

Automated summary

The study found that there are differences in cytokine responses in serum, heart, and brain between asphyxial cardiac arrest (ACA) and ventricular fibrillation cardiac arrest (VFCA), but the changes in cytokine levels and secondary injuries caused by the two types of cardiac arrest are similar.