Real time cerebral blood flow monitoring by laser speckle contrast imaging after cardiac arrest with targeted temperature management

Introduction/Background Brain injury is the main cause of mortality and mobidity after cardiac arrest (CA). Changes in cerebral blood flow (CBF) after reperfusion are associated with brain injury and recovery. Target temperature management (TTM) is the most effective treatment of CA patient. Despite of the advancement in detecting techniques, a real time CBF monitoring technique after CA and TTM, with a wide field of view and high spatiotemperal resolution, has not been established yet. Material and method Fourteen rats underwent 7 min asphyxia-CA and were randomly treated with 6 h post-resuscitation normothermic (36.5–37.5 °C) or hypothermic (32–34 °C) targeted temperature management (TTM) (n = 7). rCBF was monitored by a laser speckle contrast imaging (LSCI) technique. Brain recovery was evaluated by neurologic deficit score (NDS) and quantitative EEG - information quantity (qEEG-IQ). Results There were regional differences in rCBF among veins of distinct cerebral areas. The rostral vein had a higher rCBF at the hyperemia phase [3–12 min after return of spontaneous circulation (ROSC)] and a lower rCBF at the hypoperfusion phase (40–90 min after ROSC) compared with both the middle and caudal veins. There were heterogeneous responses among the three components of the vascular system. The rCBF of capillaries increased more than that of veins and arteries in the hyperemia phase but decreased more in the hypoperfusion phase. Hypothermia immediately following ROSC led to a longer hyperemia duration, a lower rCBF at the hypoperfusion phase, a better NDS and a higher qEEG-IQ compared with normothermic TTM. Conclusion This is the first report on continuous CBF monitoring at the level of individualized vessels with high spatial and temporal resolutions in the setting of CA. The quantified rCBF response may help uncover the mechanism of injury and recovery after global brain ischemia and TTM.