Abstract Body: Background: Automated Head Up Positioning cardiopulmonary resuscitation (AHUP-CPR) combines active compression-decompression CPR, an impedance threshold device, and automated controlled head and thorax elevation, and has been shown in pre-clinical studies to improve cerebral blood flow during CPR. However, the impact of AHUP-CPR on cerebral perfusion after ROSC is unclear. This study focused on measurement of regional cerebral perfusion after ROSC as measured by non-contrast, arterial spin labeled magnetic resonance imaging (ASL-MRI) in a porcine model.
Methods: 16 pigs (~40 kg) were anesthetized and intubated. Baseline scans were obtained in the prone position. Ventricular fibrillation was induced and left untreated for 6 minutes. Animals were randomized to AHUP-CPR or automated conventional (C) CPR and CPR was performed for 8 minutes prior to defibrillation. Epinephrine was given at 7 minutes and as needed at 3 minutes for a diastolic blood pressure of <25 mmHg. If ROSC was obtained, ASL-MRI was performed at 1 and 4 hours post ROSC in the prone position on a 3 Tesla MRI. Pseudo-continuous ASL was performed by placing a 1cm thick labeling slab perpendicular to the pharyngeal artery localized on a maximum intensity projection of a 3D time-of-flight acquisition. Image readout was performed with a multi-slice echo-planar imaging acquisition in the axial plane angulated to the anterior/posterior commissure line. Longitudinal relaxometry mapping was performed with the same slice orientation and readout strategy as the ASL acquisition to facilitate gray/white matter segmentation of the perfusion data. Regional structures of the brain were determined through registration of a publicly available porcine brain template.
Results: 7/7 AHUP-CPR pigs achieved ROSC and were imaged. Only 4/9 C-CPR pigs achieved ROSC and were imaged (p=0.03). At 1 hr post ROSC, white and grey matter mean perfusion (ml/100gm/min) to the cerebrum (Fig. 1), cerebellum (Fig. 2), and brainstem was lower in the C-CPR pigs. The differences in white and grey matter perfusion between pigs treated with AHUP-CPR of all regions 4 hrs post ROSC were found highly significant (p<0.001) when compared to C-CPR.
Conclusion: The increase in blood flow to the brain post ROSC when using AHUP-CPR may aid in understanding the survival benefit seen in pre-clinical and clinical evaluations of AHUP-CPR and warrants further investigation into the importance of regional perfusion following ROSC and AHUP-CPR.