Rise of the Machines: The era of mechanical CPR
Though research is ongoing as we learn how to optimally use these mechanical CPR devices, several products stand out as leaders in the market
By Art Hsieh
Numerous studies have shown that the ability to perform high quality chest compressions during sudden cardiac arrest (SCA) is a tremendous challenge, no matter how strong or well meaning the rescuer.
Because of this, several mechanical devices have been developed over the years to provide consistent rate and depth of compressions, and allow full recoil of the chest during CPR as recommended by the American Heart Association.1
While studies have yet to demonstrate any true advantages of mechanical CPR over human-powered compressions, research is ongoing as we learn how to optimally use these devices.
The oldest of the mechanical CPR devices is a piston-driven device commonly known as a thumper. Developed in the mid-1970s, thumpers are powered by either compressed gas or electrically. The patient’s chest is center on a baseboard; the arm of the device is centered on the sternum. Compression rate and depth is controlled electronically.
An evolution of the simple piston-based device is the addition of a suction cup that adheres to the patient’s chest. This allows the piston to not only actively press on the sternum, but also actively lift the chest back to its normal resting position, creating so-called active compression-decompression CPR (ACD-CPR). The Lund University Cardiac Arrest System (LUCAS), made by JoLife, is an example of this technology.
Another way to increase intrathoracic pressure is by constricting the overall diameter of the chest cavity during compressions.
Load-distributing band CPR devices such as the ZOLL Autopulse place a broad band across the thoracic cavity, which is tethered to a short backboard-like base. A motor pulls the two ends of the band together in a rhythmic, cyclical fashion.
Another device is not so much a mechanical compression device as one that enhances compressions overall. An impedance threshold device (ITD) such as the ResQPod, made by Advanced Circulatory Systems, is attached to a face mask or endotracheal tube, and prevents air from entering the lungs during recoil phase of chest compressions. This creates a slightly negative atmospheric pressure inside the chest, which can improve blood flow through the coronary arteries that supply blood to the cardiac tissue.
It should be stressed that there is not yet definitive data supporting or refuting the use of these devices. But the possibility of better outcomes from SCA by increasing the portability and the ease of use of mechanical devices will continue to drive innovation in this area.
1) Cave DM et al. Part 7: CPR Techniques and Devices: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2010;122;S720-S728