Abstract 08: Computed Tomography Perfusion Of Cerebral Blood Flow During Open Cardiac Massage For Hypovolemic And Normovolemic Cardiac Arrest In Swine

Abstract

Introduction: Adequate cerebral blood flow (CBF) during open cardiac massage (OCM) in cardiac arrest is critical for survivors to be neurologically intact. Cerebral perfusion is known to be poor during OCM but has not been quantified using a brain perfusion technique. The aim of this study is to measure CBF in swine undergoing OCM in hypovolemia and normovolemia using computed tomography perfusion (CTP) scanning. Methods: Anesthetized swine underwent instrumentation with right atrial and aortic pressure catheters. A pigtail catheter placed in the ascending aorta was used to administer iodinated contrast and CTP imaging acquired. Brain parenchymal attenuation was measured over time from which CBF (mL/100g of brain) and time to peak (TTP; secs) were derived. Animals were then euthanized exsanguination (hypovolemic group) or potassium chloride injection (normovolemic group). Animals were subject to a clamshell thoracotomy, OCM and repeated CTP. Data pertaining to peak coronary perfusion pressure (pCPP; mmHg) was collected and % CPP >15mmHg (% CPP; secs) calculated post hoc. Results: Normovolemic animals achieved superior pCPP compared to the hypovolemic animals (pCPP: 39.3 vs 12.3, p<0.001; % CPP: 14.5 ± 1.9 vs 30.9 ± 6.5, p<0.001). CTP was successfully performed during OCM generating an attenuation curve (figure). The TTP elongated from spontaneous circulation, normovolemia to hypovolemia (5.7 vs 10.8 vs 14.8, p=0.01). CBF during OCM was similar between hypovolemic and normovolemic groups (7.5 ± 8.1 vs 4.9 ± 6.0, p =0.73) which was lower than baseline values (51.9 ± 12.1, p<0.001). Conclusions: OCM in normovolemia generates superior coronary hemodynamics compared to hypovolemia. Despite this, neither generates adequate CBF as measured by CTP, compared to baseline. To improve the rate of neurologically intact survivors, novel resuscitative techniques need to be investigated that specifically target cerebral perfusion as existing techniques are inadequate.