Synergy of Elevation of the Head and Thorax and REBOA During Out-of-Hospital Cardiac Arrest

Overview

Long-term neurological outcome after successful resuscitation of cardiac arrest remains poor, mainly due to cerebral hypoperfusion and severe hypoxic-ischemic brain injuries. Automated head and chest elevation during cardiopulmonary resuscitation (AHUP-CPR) improves cerebral perfusion by decreasing the intracranial pressure and increasing cerebral perfusion in experimental pig studies. The addition of an impedance threshold device (ITD) and active chest compression-decompression device (ACD) improved hemodynamics and cerebral perfusion. In addition, early implementation of AHUP-CPR in patients with out-of-hospital cardiac arrest (OHCA) was associated with improved survival to hospital discharge, in a multicenter observational study. A 2-year prospective clinical trial in Grenoble evaluating this combination was just completed. This study showed for the first time that the value of end-tidal CO2 (EtCO2), a surrogate for cardiopulmonary resuscitation (CPR) quality and cardiac output, measured with this combination therapy, was significantly higher than with standard CPR. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has recently been proposed during CPR. This technique temporarily diverts blood flow to the coronary and cerebral circulation. Its beneficial effect on hemodynamics, cerebral blood flow and survival has been experimentally validated. In several feasibility studies, encouraging results were observed by slightly optimizing cerebral perfusion and coronary pressure when REBOA was used in combination with standard CPR. In a porcine model of cardiac arrest, the addition of REBOA to AHUP CPR was associated with a marked improvement in coronary perfusion pressure and near-normalization of cerebral perfusion pressure. These two interventions act synergistically. REBOA directs flow and pressure to the heart and brain, while AHUP CPR improves preload on the right side of the heart and reduces intracranial pressure. The aims of this clinical investigation are to assess the feasibility of placing a REBOA catheter combined with automated CPR with head and chest elevation, and to quantify the associated changes in clinical parameters for OHCA.

Cardiac arrest remains a leading cause of death, currently affecting more than 275,000 patients in Europe and in the US, annually. As recommended by the American Heart Association (AHA) and the European Resuscitation Council (ERC), the current standard of care for patients with an out-of-hospital cardiac arrest (OHCA) includes manual cardiopulmonary resuscitation (S-CPR). Nearly two-thirds of all patients who suffer from sudden cardiac death are male and their average age is approximately 65 years old. Survival rates from this major health epidemic have remained largely unchanged for decades. The current standard of care for patients with an out-of-hospital cardiac arrest (OHCA) includes manual cardiopulmonary resuscitation (CPR) delivered at a rate of 100 compressions per minute with a depth of 5 cm (maximum 6 cm). Periodic positive pressure ventilations are recommended to assure adequate oxygenation and periodic inflation of the lungs. This method of CPR has been shown in animals to provide 15-30% of normal blood flow to the heart and brain. Although closed-chest manual S-CPR was initially described more than 50 years ago, survival rates remain low. In Europe and in the US, survival with favorable neurological outcome for all patients following OHCA and treated with S-CPR averages \<6% (ranging from \<1% to 20%). In addition to the challenges associated with performance of high-quality CPR in a timely manner, closed chest manual CPR is inherently limited due to the lack of mechanical optimization of flow and pressure with conventional CPR. The consequence of this limitation is that blood flow is far less than normal to the brain and other vital organs and brain pressures during the compression phase are too high. Better alternatives that more closely mimic normal physiology are needed. Automated head and thorax elevation during cardiopulmonary resuscitation (AHUP-CPR) improves cerebral perfusion by decreasing intra-cranial pressure and increasing cerebral perfusion in experimental swine studies. The addition of an impedance threshold device (ITD) and active chest compression-decompression (ACD) improved hemodynamics and cerebral perfusion. Moreover, early implementation of AHUP in out-of-hospital cardiac arrest (OHCA) patients was associated with better survival to hospital discharge, in a multicenter observational study. The investigator had just completed a 2-year prospective clinical trial in Grenoble assessing this combination. This study showed, for the first time, that End-Tidal CO2 value, a surrogate for CPR quality and cardiac output, measured using this combination therapy, was significantly higher compared with standard CPR. Moreover, it was recently showed the importance of an early implementation of these devices to improve survival. Also, as all these devices have a European Union declaration of conformity (CE mark), this technique of CPR should be proposed as a basic life support, done by the rescuers. The Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) involves inserting a catheter with a balloon at its tip into a large artery, typically the femoral artery. The catheter is threaded through the blood vessels until it reaches the aorta. Once the catheter is in place, the balloon is inflated to temporarily stop blood flow in the aorta. This halts the blood flow to the lower part of the body and redirects it to the critical organs in the chest and brain. REBOA is widely used in acute trauma care in order to stop massive hemorrhages in the lower part of the body. The use of REBOA was proposed for traumatic cardiac arrest in the latest European Resuscitation Council (ERC) guidelines as an option to stop bleeding. However, REBOA has recently been proposed at the early phase of non-traumatic cardiac arrest in case of failure of initial resuscitation's maneuvers (CPR and first defibrillations attempts). This technique temporarily diverts blood flow towards the coronary and cerebral circulation. It has already shown that, during CPR, when coronary perfusion pressure increase, the chance of ROSC increase too. Moreover, REBOA could increase mean arterial pressure and thus increase cerebral perfusion pressure, defined by the difference between mean arterial pressure and intracranial pressure. The beneficial effects on hemodynamics, cerebral blood flow and survival of REBOA have been already validated experimentally. In several feasibility studies, encouraging results have been observed by slightly optimizing cerebral and coronary perfusion when REBOA was used in combination with standard CPR. In a porcine model of cardiac arrest, the addition of REBOA to AHUP-CPR was associated with greatly improved coronary perfusion pressure and almost normalization of cerebral perfusion pressure. Indeed, REBOA increase mean arterial pressure and provide directed flow and pressure to the heart while AHUP-CPR decrease intracranial pressure and improves preload to the right side of the heart, improving cerebral perfusion pressure. In addition with AHUP-CPR, the use of REBOA could highly improve survival rates for cardiac arrest patients. The aims of the present study project are to evaluate the feasibility of implementing REBOA catheter combined with automated head and thorax elevation CPR and to quantify associated changes in clinical parameters for OHCA patients