Contrast-Enhanced Ultrasound of Brain Perfusion in Cardiopulmonary Resuscitation

To evaluate the feasibility and potential utility of contrast-enhanced ultrasound for real-time imaging of whole-brain perfusion during cardiopulmonary resuscitation (CPR), cardiac arrest was induced in 8- to 7-week-old 10-kg piglets (Sus scrofa domesticus). Contrast-enhanced ultrasound was performed through a parietal cranial window in the coronal plane visualizing the thalami during hemodynamic-directed CPR. Whole-brain mean and maximum pixel intensities in each slice during resuscitation were calculated. Piglets were monitored for 24 hours postarrest. Seven piglets achieved return of spontaneous circulation and 6 survived to 24 hours. Of the 6 surviving piglets, 2 piglets demonstrated greater intra-CPR brain enhancement at maximum 73.2% and 42.1% and mean 36.7% and 31.9% enhancement above background, respectively, compared with maximum 5.8%, 22.9%, 6.0%, and 26.6% and mean 5.1%, 8.9%, 2.9%, and 6.6% above background, respectively, in the other 4. Intra-CPR average mean arterial pressures were similar between all 6 surviving piglets. One piglet achieved return of spontaneous circulation but expired 10 minutes later with enhancement maximum 45.2% and mean 18.9% enhancement above background. The final piglet did not achieve return of spontaneous circulation and exhibited minimal enhancement at maximum 2.8% and mean 0.9% enhancement above background. Contrast-enhanced ultrasound can detect brain perfusion during CPR, identifying a spectrum of cerebral blood flow responses in the brain despite similar systemic hemodynamics. This novel application can form the basis for future large animal model studies and eventually human clinical studies to further explore the neurologic implications of cerebral blood flow responses during resuscitation and stimulate novel strategies for optimizing brain perfusion restoration.