Dynamic heterogeneity of cerebral hypoperfusion after prolonged cardiac arrest in dogs measured by the stable xenon/CT technique: a preliminary study

Part 9: Post–Cardiac Arrest Care

“…93,94 After ROSC there is an initial hyperemic blood flow response that lasts 10 to 30 minutes, followed by a more prolonged period of low blood flow. 95,96 During this latter period of late hypoperfusion, a mismatch between blood flow (as a component of oxygen delivery) and oxygen requirement may occur. Hyperventilation at this stage may lower PaCO 2 , cause cerebral vasoconstriction, and exacerbate cerebral ischemic injury.…”

Post–Cardiac Arrest Syndrome

“…42,43 This impaired reflow can cause persistent ischemia and small infarctions in some brain regions. The cerebral microvascular occlusion that causes the no-reflow phenomenon has been attributed to intravascular thrombosis during cardiac arrest and has been shown to be responsive to thrombolytic therapy in preclinical studies.…”

“…43,46 In the recent Thrombolysis in Cardiac Arrest (TROICA) trial, tenecteplase given to patients with out-of-hospital cardiac arrest of presumed cardiac origin did not increase 30-day survival compared with placebo (B.J.B., personal communication, February 26, 2008).…”

“…56 These results do not rule out the potential presence of regional microcirculatory reperfusion deficits that have been observed in animal studies despite adequate CPP. 43,46 Overall, it is likely that the CPP necessary to maintain optimal cerebral perfusion will vary among individual post-cardiac arrest patients at various time points after ROSC.…”

“…The optimal MAP in the post-cardiac arrest period might be dependent on the duration of cardiac arrest, with higher pressures needed to overcome the potential no-reflow phenomenon observed with Ͼ15 minutes of untreated cardiac arrest. 42,43,136 At the opposite end of the spectrum, a patient with an evolving acute myocardial infarction or severe myocardial dysfunction might benefit from the lowest target MAP that will ensure adequate cerebral oxygen delivery.…”