Over 750,000 citizens of the US and Europe suffers sudden cardiac arrest each year, and survival remains dismal: over 75% of victims do not leave the hospital alive. Cardiac arrest requires treatment within minutes to attain survival. Cardiopulmonary resuscitation (CPR) and electrical defibrillation remain the two crucial interventions that can be life-saving during cardiac arrest. Through CPR training offered by the American Heart Association (AHA) and other organizations, laypersons can provide treatment to cardiac arrest victims before the arrival of emergency medical personnel. This review will summarize current knowledge about the importance of CPR in the treatment of cardiac arrest, and will describe several exciting new technologies that will make CPR more effective in coming years.

The Clinical Importance of CPR :

A number of studies have confirmed that CPR can be life-saving when provided either by laypersons or medical professionals. In several large investigations, the prompt delivery of CPR served as an important predictor of survival—bystander CPR may almost double the chance of survival. Other work has shown that the probability of survival from cardiac arrest falls by 10–15% per minute without treatment, and well-performed CPR likely shifts this curve towards higher probability of survival. Furthermore, recent investigations have suggested that CPR maintains the heart in a state favorable for defibrillation. That is, fatal cardiac arrhythmias common in cardiac arrest have a greater chance of being successfully terminated by electrical shock if CPR is performed first. Recent work has also shown that during actual human CPR, shallow chest compressions have an adverse impact on outcomes. Therefore, it is crucial that CPR be performed in accordance with published guidelines, which are formulated based on the best available data and updated every five years. Given the importance of CPR quality, it is perhaps surprising that the performance of CPR has only recently been assessed during actual cases of cardiac arrest. In a number of investigations over the past few years, CPR quality was found to be lacking during both in-hospital and out-of-hospital cardiac arrest, both in Europe and the US. In other words, poor CPR quality is endemic. In general, chest compressions are delivered too slowly and in too shallow a fashion, and ventilations are given too rapidly. There are several reasons why this might be the case despite the best intentions of providers. First,CPR is deceptively simple to describe and remarkably difficult to perform, as humans generally do not have a good internal sense of timing to recognize 100 compressions or 8–12 ventilations per minute, and fatigue often prevents adequate depth efforts. Second, CPR is taught in the sterile conditions of a classroom, but performed in the volatile environment of a dramatically ill person surrounded by anxious onlookers—training can be easily forgotten in the panic of the moment, especially if that training has not taken place recently. Third, CPR courses until recently did not adequately emphasize the importance of CPR quality as a determinant of survival. Improving CPR and Cardiac Arrest Care What, then, can be done to improve the care of cardiac arrest patients? It is clear from a variety of data that the majority of cardiac arrest patients do not receive CPR at all until the arrival of medical personnel precious minutes after the onset of arrest. CPR training must be simplified and widely disseminated. Why, for example, can we not require CPR competence as a prerequisite for a driver’s license, or provide CPR training to every parent during the hospital stay before the birth of their child or before they leave the hospital with their newborn? CPR quality must also be improved. A variety of new technologies have been developed over the past decade to assist in this goal. First, devices have been developed that detect CPR parameters during actual resuscitation, and these devices can trigger alarms or audio messages when incorrect CPR is detected, for example if the chest compression rate is too slow. Such devices assist the provider during human CPR by acting as real-time ‘CPR coaches’, and are currently being marketed by a number of biomedical companies. Second, devices are currently in use that delivers CPR mechanically, via either a motorized compression band wrapped around the chest or a compressed-air driven piston pump. These tools provide uniform chest compression rate and depth by removing the human performance element. Clinical studies are currently under way with both audio- feedback and mechanical compression devices to assess whether they improve patient outcomes.