Mechanical chest compression machines for cardiac arrest


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Review question

We reviewed which method of chest compressions (applying the traditional hand technique versus using a machine) resulted in more lives saved during cardiopulmonary resuscitation (CPR) for cardiac arrest.

Background

‘Sudden cardiac arrest’ occurs when someone’s heart stops beating unexpectedly. Cardiopulmonary resuscitation, referred to as CPR, involves rhythmical pushing on the chest of a cardiac arrest victim to provide forward blood flow. This can keep blood flowing to the victim’s vital organs while the heart is not pumping. CPR has been shown to improve the chance that the heart will restart and the victim will survive. Machines have been developed to take over this chest pumping action using automated pistons, pneumatic vests, or band-like mechanisms. The theory is that these machines should be able to provide a more effective pumping action than is seen in humans because the machines do not pause or get tired. Furthermore, they provide consistent pressure and timing of each chest compression in line with latest evidenced-based practice. Some preliminary studies using these machines have shown that they are easy to use and can save people with cardiac arrest. This is an update of the Cochrane Review on mechanical chest compression devices originally published in 2011 and updated last in 2014.

Study characteristics

The evidence is current to August 2017. We searched the literature and found a total of 2554 citations that were potentially relevant. After reviewing each of these, we found 11 articles describing clinical trials that could help us answer our question. Taken together, these trials included 12,944 adult participants who suffered cardiac arrest either in-hospital or out-of-hospital. The newest studies identified in this update are larger and of higher quality than those that had been identified in prior versions of this review. Several studies were sponsored by device manufacturers.

Key results

We found that available studies have important differences from one another. The most important differences were the type of mechanical device studied and the type of CPR protocol provided for patients assigned to the manual chest compression group. These differences make comparisons across studies challenging. Some studies reported improvements in rate of survival for patients treated with mechanical chest compressions compared to patients treated with manual chest compressions, while others reported no difference or even suggested harm associated with mechanical chest compressions. When considering all of the identified studies together, it seems like mechanical chest compression devices probably have a very similar effect on survival when compared with high-quality manual chest compressions.

Quality of evidence

With the inclusion of several large studies, the overall quality of evidence has improved considerably, and now may be considered to be of low to moderate quality.