Resuscitation science has come a long way since 1906 when George Crile and David Dolley found that they could temporarily resuscitate mastiffs using a combination of a chest compression, saline, and 1–2mg of intravenous (IV) adrenaline (our current dosing originates from this research). The first defibrillation in a human was performed 41 years later by Claude Beck from Ohio using two metal tablespoons as internal paddles to shock the heart of a 14-year-old who had arrested mid cardiac surgery. Between 1956 and 1958, Peter Safar—the father of modern resuscitation and founder of the first intensive care unit—invented cardiopulmonary resuscitation (CPR) and mouth-to-mouth ventilation. In 1966, Frank Pantrige and John Geddes created a mobile intensive care ambulance with the world's first portable defibrillator in Belfast. Resuscitation in cardiac arrest is far from a settled science and each decade sees major advances, and a paring back of less effective interventions.
There are five key areas where this field is expanding: rapid alerting and bystander response, defibrillation techniques, optimising pressure and flow using exogenous catecholamines, extracorporeal perfusion, and cellular preservation therapies.
Research involving community responders, improving automated external defibrillator (AED) accessibility (perhaps even using drones) and increasing bystander CPR rates are probably some of the most important areas of work that are ongoing. Of particular interest, the FIRST trial in Australia and New Zealand has equipped community members with a small disposable ‘CellAED®’ to test whether this can help improve survival.
The dual sequential defibrillation study led by Sheldon Cheskes from Canada has had a significant impact on practice, and research on how to best achieve effective cardioversion in ventricular fibrillation (VF)/ventricular tachycardia (VT) arrest is forging ahead.
The ideal dose of adrenaline (if any) is unknown. Therefore, strategies to improve cardiac and cerebral perfusion (improving flow, not just measurable pressures) continue to be scrutinised. Subgroup analyses of the PARAMEDIC-2 trial spurred researchers to question whether earlier adrenaline might improve survival, giving birth to PARMEDIC-3 which will investigate IV vs intraosseous (IO) adrenaline in OHCA. American researchers are also examining whether higher-dose intramuscular (IM) adrenaline might be a better solution, opening up the possibility of bystanderadministered ‘epinephrine’. On the topic of flow and pressure, research from South Korea carried out almost two decades ago is finally in the spotlight and we are now fairly convinced that up to half of all CPR compressions occur over the aortic outflow of the heart, rather than the ventricles, potentially obstructing flow. We still don't know what to do with this information; however, intra-arrest cardiac ultrasound might be a solution. Whether we can use this to optimise compression location, and if it will make a difference to overall neurologically intact survival remains to be seen. It is possible that trans-oesophageal echocardiography (TOE), which allows superior cardiac ultrasound views, will become more commonplace as a result. What began with the SAMU de Paris initiating extra-corporeal life support (ECLS) is now being trialled by specialist teams around the world. However, artificial perfusion therapies will continue to be limited by high cost and geographic inequality for some time. Cell preservation and tissue protective therapies and medications remain an area of high interest despite being the least commonly discussed. These are the ‘holy grail’ of resuscitation, the aim being to switch off the cell death signals inside hypoxic tissue and put cells into hibernation mode until circulation can be restored, ultimately preventing brain death. They are a long way from clinical application; however, the science of resuscitation continues to develop and evolve and irrespective of any trial's outcome, the future is bright and what we do matters.