Reversal of the No-Reflow Phenomenon after Prolonged Cardiac Arrest by Controlled Automated Reperfusion of the Whole Body: Preliminary Results of an Ongoing [15O] Water Pet Study

1594 Aim: Despite continuous effort and progress in the field of cardiopulmonary resuscitation (CPR), survival after twenty minutes of cardiac arrest (CA) remains rare and is usually associated with neurological impairment. One major cause seems to be the cerebral no-reflow phenomenon which has been reported even hours after return of spontaneous circulation (ROSC). The aim of the present ongoing study was to investigate the no-reflow phenomenon during reperfusion by high-flow, pulsatile extracorporeal circulation (ECC) after 20 min of CA. Methods: Until the date of submission, N=4 pigs (German landrace) underwent 20 minutes of CA induced by ventricular fibrillation and were treated with high-flow, pulsatile ECC for up to two hours. This also entailed hypothermia, head elevation by 30° and a hyperosmolar priming solution. Cerebral blood flow (CBF) was measured quantitatively at baseline and at multiple times during reperfusion by positron emission tomography (PET) with [15O]water and arterial blood sampling. Results: After 8 ± 3 min of ongoing reperfusion, global CBF (21.0 ml/min/100g) was decreased by on average 38 % (range: -6 to -69%) compared to baseline before CA (33.7 ml/min/100g). At this time point, regional analysis revealed absent cortical perfusion (no-reflow), while CBF of mesencephalon and cerebellum was preserved to increased. Subsequently, CBF increased within the first hour of ECC to CBF levels above baseline in all regions. At one hour after start of ECC global CBF exhibited a mean increase of 102 % (range: +3 to +238%) compared to baseline. Conclusions: For the first time, we report the successful measurement of CBF using [15O]water and PET during ECC. High-flow, pulsatile extracorporeal circulation showed the potential to overcome the cerebral no-reflow phenomenon after prolonged CA. The observed CBF increase after one hour of ECC exceeded values reported in the literature for ROSC following conventional CPR. However, possible differences in anesthesia and physiological parameters have to be considered. Further research is needed to clarify whether ECC may contribute to an improved neurological outcome after CA.