Abstract 20736: Ischemic Postconditioning Requires High-Quality CPR and Epinephrine to Improve Cardiac Mitochondrial Respiration After Prolonged Cardiac Arrest
Introduction: Ischemic postconditioning (IPC) has been shown to improve cardiac mitochondrial respiration during CPR and left ventricular ejection fraction post-ROSC in a porcine model of prolonged cardiac arrest compared to standard CPR. IPC during CPR (IPC-CPR) also increased coronary perfusion pressure (CPP) after bolus IV epinephrine. We investigated if the increased CPP obtained during IPC-CPR is required for improvement of cardiac mitochondrial respiration by: a) controlling CPP to <30mmHg via shallow chest compressions and, b) by withholding epinephrine during CPR.
Methods: After 15 min of ventricular fibrillation, 36 intubated and isoflurane anesthetized female pigs were randomized to receive standard CPR (S-CPR, n=11), IPC (IPC, n=11), IPC with controlled CPP (IPC-ConCPP, n=8), or IPC without epinephrine (IPC-NoEpi, n=6). All groups, except IPC-NoEpi, received 0.5 mg of epinephrine at minute 3 of CPR. IPC consisted of 3 cycles of 20 sec compression / 20 sec pause for the first 2 min of CPR. Cardiac mitochondria were isolated via differential centrifugation 4 min after initiation of CPR. Respiration and calcium retention capacity (CRC) were measured for complex I (pyruvate+malate) and II (succinate+rotenone) substrates. Respiratory control index (RCI) was calculated as the ratio of states 3 to 4 respiration. Data were compared with ANOVA.
Results: CPP during the 4th minute of CPR and complex I RCI were higher in the IPC-CPR group compared to all other groups. IPC also resulted in higher complex II RCI compared to S-CPR and IPC-NoEpi, but not compared to IPC-ConCPP. CRC was not different between groups.
Conclusions: IPC during CPR with high-quality chest compressions and epinephrine increased CPP. Increased CPP is associated with increased cardiac mitochondrial respiration. IPC increased cardiac mitochondrial respiration after prolonged cardiac arrest only in the setting of high-quality mechanical CPR with epinephrine.
Author Disclosures: T.R. Matsuura: Research Grant; Significant; American Heart Association Predoctoral Fellowship. J.A. Bartos: None. M.D. Olson: None. A. Tsangaris: None. K. Chandra Shekar: None. S.A. George: None. J.N. Rees: None. S.H. McKnite: None. M.L. Riess: None. R.W. Neumar: None. M. Bienengraeber: None. T.P. Aufderheide: Other; Modest; Volunteer Co-Chair AHA ReSS. D. Yannopoulos: None.
- © 2016 by American Heart Association, Inc.