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Chest compressions are essential in cardiac arrest resuscitation. In consideration of ECMO, chest compressions generate coronary perfusion pressure (CPP), and a CPP of at least 20 mmHg is important for achieving return of spontaneous circulation (ROSC) [2]. Multiple studies highlight the role of early chest compressions in survival from cardiac arrest [3–6].

The most recent BLS and ACLS guidelines emphasize the delivery of continuous chest compressions with as few interruptions as possible [1]. Several consecutive chest compressions are necessary to generate adequate CPP [7]. CPP drops off immediately when chest compressions are discontinued [8]. The proportion of resuscitation time without chest compressions, termed hands‐off time or no‐flow fraction, is inversely associated with cardiac arrest survival [9]. Compression depth, rate, and full recoil are also critical characteristics for effectiveness.

Prior work has highlighted the often‐substandard CPR performed by prehospital and in‐hospital clinicians. In a series of prehospital cardiac arrests in Europe, chest compressions were delivered on average only half of the time while the patient was in arrest, and most compressions were too shallow [10]. There have been similar observations made in analyses of in‐hospital resuscitations [11].

Delivering chest compressions during cardiac arrest resuscitation poses practical challenges. The treating EMS team must provide continuous chest compressions with as few interruptions as possible and must ensure high‐quality chest compressions with adequate depth, rate, and recoil. To achieve these chest compression goals, additional rescuers should be dispatched to provide assistance at cardiac arrests. Team members providing chest compressions should rotate frequently, ideally every 1‐2 minutes [1].

Several cardiac monitors use a compression paddle or other technology to measure the depth and rate of chest compressions [10, 11]. These monitors are able to provide real‐time audio or visual feedback, indicating to the rescuer whether or not to increase the depth or rate. Audiovisual feedback improves chest compression performance [12].

Various mechanical devices for automating chest compressions are now available. The Thumper (Michigan Instruments, Grand Rapids, MI) has been used for approximately 40 years and provides chest compressions using a pneumatic piston [13]. The Autopulse Resuscitation System (Zoll Corporation, Chelmsford, MA) facilitates chest compressions using a circumferential load‐distributing band [14, 15]. The Lund University Cardiopulmonary Assist Device (LUCAS) (Lund, Sweden) provides active compression and decompression through a pneumatic piston attached to a suction cup on the chest [16].

The scientific data evaluating the effectiveness of these devices remain inconclusive. One urban EMS agency evaluated the Autopulse in a before‐after fashion and found increases in both ROSC and survival [14]. However, a larger, multicenter, randomized controlled trial demonstrated worsened outcomes with the intervention [15]. The authors attributed this observation to potential delays in CPR required to place and activate the device. The LUCAS device was effective in a small study of 100 patients, but its benefit was noted only in those who received it within 15 minutes from the ambulance call [16].

Data suggest there is no difference in survival, but these devices may be useful in settings where high‐quality manual CPR cannot be provided (e.g., moving ambulance, limited personnel, prolonged resuscitation, concern for exposure to infectious disease) [17, 18]. It is important to note that each device requires time to place on the patient, during which no compressions occur. Any protocol that incorporates the use of mechanical devices must stress the importance of continuing manual compressions as much as possible until the device starts. For these reasons, mechanical devices are best reserved for prolonged resuscitative efforts and not as initial therapy, so long as there are sufficient numbers of rescuers to assist.