Novel gas mixture combined with an auto-transfusion tourniquet enhances cerebral O2 transport and hemodynamic indices in CPR swine. Part B - A pilot experimental study.

ABSTRACT

Objectives: The cognitive outcome of CPR is poor. This study aims to evaluate if enhancing blood flow to the brain and oxygen dissociation from the hemoglobin improve cerebral O2 transport during CPR in cardiac arrest swine. Methods: Standard swine-CPR model of induced VF and recovery was treated with an auto-transfusion tourniquet (A-TT®; HemaShock® (HS) Oneg HaKarmel Ltd. Israel) and ventilation with a novel mixture of 30% Oxygen, 5% CO2, and 65% Argon (COXAR™). Five swine received the study treatment and 5 controls standard therapy. Animals were anesthetized, ventilated, and instrumented for blood draws and pressure measurements. Five minutes of no-CPR arrest were followed by 10 min of mechanical CPR with and without COXAR-HS™ enhancement followed by defibrillation and 45 min post ROSC follow-up. Results: All 5 COXAR-HS™ animals were resuscitated successfully as opposed to 3 of the control animals. Systolic (p < 0.05), and diastolic (p < 0.01) blood pressures, and coronary (p < 0.001) and cerebral (p < 0.05) perfusion pressures were higher in the COXAR-HS™ group after ROSC, as well as cerebral flow and O2 provided to the brain (p < 0.05). Blood pressure maintenance after ROSC required much higher doses of norepinephrine in the 3 resuscitated control animals vs. the 5 COXAR-HS™ animals (p < 0.05). jugular vein PO2 and SO2 exceeded 50 mmHg and 50%, respectively with COXAR-HS™. Conclusions: In this pilot experimental study, COXAR-HS™ was associated with higher diastolic blood pressure and coronary perfusion pressure with lower need of vasopressors after ROSC without significant differences prior to ROSC. The higher PjvO2 and SjvO2 suggest enhanced O2 provision to the brain mitochondria, while limb compression by the HS counteracts the vasodilatory effect of the CO2. Further studies are needed to explore and validate the COXAR-HS™ effects on actual post-ROSC brain functionality.