Refractory Out-Of-Hospital Cardiac Arrest Treated With Mechanical CPR, Hypothermia, ECMO and Early Reperfusion

Overview

Sudden out-of-hospital cardiac arrest (OHCA) is a leading cause of death in Australia. The most common cause of OHCA is a heart attack. The current treatment of OHCA is resuscitation by ambulance paramedics involving CPR, electrical shocks to the heart, and injections of adrenaline. In more than 50% of cases, paramedics are unable to start the heart and the patient is declared dead at the scene. Patients with OHCA who do not respond to paramedic resuscitation are not routinely transported to hospital because it is hazardous for paramedics to undertake rapid transport whilst administering chest compressions and there is currently no additional therapy available at the hospital that would assist in starting the heart. However, a number of recent developments suggest that there may be a new approach to the resuscitation of this group of patients who would otherwise die. Firstly, Ambulance Victoria have recently introduced portable battery powered machines that allow chest compressions to be safely and effectively delivered during emergency ambulance transport. Second, The Alfred ICU will shortly be implementing a new protocol whereby the patient in cardiac arrest can immediately be placed on a heart-lung machine. This is known as extra-corporeal membrane oxygenation (ECMO). Third, the brain can now be much better protected against damage due to lack of blood flow using therapeutic hypothermia which is the controlled lowering of body temperature from 37°C to 33°C. Clinical trials have demonstrated that this significantly decreases brain damage after OHCA. Finally, The Alfred Cardiology service has an emergency service for reopening the blocked artery of the heart in patients who present with a sudden blockage of the heart arteries. This is currently not used in patients without a heart beat because of the technical difficulty of undertaking this procedure with chest compressions being undertaken. This study proposes for the first time to implement all the above interventions when patients have failed standard resuscitation after OHCA. When standard resuscitation has proved futile, the patient will be transported to The Alfred with the mechanical chest compression device, cooled to 33°C, placed on ECMO, and then transported to the interventional cardiac catheter laboratory. The patient will then receive therapeutic hypothermia for 24 hours. Subsequent management will follow the standard treatment guidelines of The Alfred Intensive Care Unit.