Real-time monitoring of cerebral blood flow by laser speckle contrast imaging after cardiac arrest in rat

Cardiac arrest (CA) results in global brain ischemia. To explore the role of cerebral blood flow (CBF) during ischemia, laser speckle contrast imaging (LSCI), a full-field high-resolution optical imaging technique, was used for real-time monitoring of the fluctuations of CBF in a rat model of asphyxial-CA. The temporal changes of CBF were characterized and the relationship between CBF and mean arterial pressure (MAP) was evaluated. Asphyxial-CA led to transient CBF dysregulation, manifested by changes in CBF velocity were significantly impacted by MAP. Hyperemia is aligned with a bolus injection of vecuronium, the first two minutes of asphyxia, the time of epinephrine injection and cardiopulmonary resuscitation, and then lasted for 13 min after the return of spontaneous respiratory (ROSC), followed by hypoperfusion about 55-70% of baseline level no later than 40 min after ROSC. Interestingly, we found that the velocity of venule blood flow increased more than that of the arteriole blood flow during the hyperemia (176% vs 120%). Our study, for the first time, shows real-time CBF changes during and immediately after asphyxial-CA, with high spatial and temporal resolution images. The quantified cerebro-vascular response during the different phases of recovery after CA may underlie the mechanism of injury and recovery after brain ischemia. The study provides a new technique to study the neurovascular coupling and metabolic regulation of CBF after CA.