Abstract P50: Ischemic Post-Conditioning Following Global Ischemia Due to Cardiac Arrest Failed to Improve Cardiac Function and Survival
Introduction: Repetitive episodes of ischemia and reperfusion following regional myocardial and cerebral ischemia, representing ischemic post-conditioning (IPC), protect against ischemic injury. The possibility that such may have functional application for myocardial injury and survival in settings of cardiac arrest and resuscitation was examined. We hypothesized that repetitive cycles of ventricular fibrillation and reperfusion following resuscitation, representing IPC, would improve cardiovascular function and survival.
Methods: Ventricular fibrillation (VF) was electrically induced in 10 SD rats weighing 536±15 g and left untreated for 8 minutes prior to 6 minutes of uninterrupted pre-cordial compressions followed by attempted defibrillation. Resuscitated animals were randomized to either IPC or control. IPC was induced at 5 minutes with electrical re-fibrillation lasting 30 sec followed by spontaneous reversion to a perfusing rhythm. The IPC was repeated 5 minutes later. Except for IPC, controls were identically treated. Frontal plane ECG, mean arterial blood pressure, left ventricular pressures and end tidal CO2 were continuously recorded. Left ventricular ejection fraction (EF) and cardiac output (CO) were measured echocardiographically at hourly intervals together with blood gases for a total of four hours. Survival was documented at the end of 72 hours.
Results: Baseline values did not differ between the IPC and control group. No statistically significant differences between the groups were demonstrated. A power calculation indicates that a minimum of 240 animals would be required to find a difference that would be potentially significant, accordingly the study was concluded. Table⇓. Mean values with standard deviation.
Conclusion: The potential value of ischemic post-conditioning represented by repetitive episodes of VF, under the conditions of global ischemia of cardiac arrest, failed to demonstrate a survival value.