Cerebral ischaemia in experimental cardiopulmonary resuscitation — comparison of epinephrine and aortic occlusion

The apparent inability of epinephrine to improve outcome after cardiopulmonary resuscitation (CPR) could be caused by direct negative effects on the cerebral circulation. Constant aortic occlusion with a balloon catheter could be an alternative way to improve coronary and cerebral perfusion during CPR. The objective of the present study was to compare the effects of standard-dose epinephrine with balloon occlusion of the descending aorta on cortical cerebral blood flow augmentation during CPR. Ventricular fibrillation was induced in 24 anaesthetised piglets. A non-intervention interval of 9 min was followed by open-chest CPR. The animals were randomised to receive repeated intravenous bolus doses of epinephrine 20 μg/kg or balloon occlusion of the descending aorta. Focal cortical cerebral blood flow was measured continuously using laser-Doppler flowmetry. Balloon occlusion of the aorta resulted in a significantly higher mean cortical cerebral blood flow and a lower cerebral oxygen extraction ratio than epinephrine during CPR. After restoration of spontaneous circulation the cerebral perfusion appeared compromised to the same extent in both groups, with lower blood flow compared to baseline, high cerebral oxygen extraction and cerebral tissue acidosis. No difference in cerebral cortical vascular resistance between the two groups could be detected. It is concluded that aortic balloon occlusion was superior to epinephrine in cerebral blood flow augmentation during resuscitation and did not generate adverse effects on cerebral blood flow, oxygenation or tissue pH after restoration of spontaneous circulation. No evidence of cerebral vasoconstriction induced by standard-dose epinephrine was found. A aparente incapacidade da epinefrina para melhorar o prognóstico das vı́timas pós-paragem cardiorespiratória (PCR) poderá estar relacionada com os efeitos negativos na circulação cerebral. A oclusão contı́nua com um cateter com balão poderia ser uma boa alternativa para melhorar a perfusão cerebral e miocárdica no contexto de PCR. O objectivo deste trabalho foi o de comparar o impacto na perfusão do córtex cerebral, de doses habituais de epinefrina com a oclusão da aorta descendente por um balão, guiado por cateter. Foi induzida fibrilhação ventricular em 24 porcos anestesiados. Após 9 minutos de PCR sem qualquer intervenção, os animais foram submetidos a massagem cardı́aca aberta. O animais foram randomizados para receber doses repetidas de epine