Using mechanical devices to perform consistent chest compressions during resuscitation efforts does not improve survival compared to manual chest compressions in people who have a cardiac arrest outside of a hospital, according to late-breaking resuscitation research presented at the American Heart Association's Scientific Sessions 2014 and simultaneously published in Lancet.

Using mechanical devices could overcome problems such as differing levels of skill among rescuers and deteriorating quality of compressions as fatigue sets in. However, until this study there had been little evidence of whether or not the devices are effective in saving lives.

The pre-hospital randomized assessment of a mechanical compression device in cardiac arrest (PARAMEDIC) trial compared 30-day survival rates in patients who experienced non-trauma-related cardiac arrest outside of a hospital and were randomly assigned to receive manual chest compressions or compressions delivered via the LUCAS-2, a lightweight, portable, electrically-powered device.

The primary outcome was survival at 30 days following cardiac arrest and was analyzed by intention to treat. Ambulance dispatch staff and those collecting the primary outcome were masked to treatment allocation. Masking of the ambulance staff who delivered the interventions and reported initial response to treatment was not possible.

The study found that 30-day survival was similar after mechanical (6.3 percent) and manual (6.9 percent) compressions among 4,471 eligible patients treated by four ambulance services in the United Kingdom (1,652 randomized to LUCAS-2 and 2,819 to manual compressions).

In secondary findings, LUCAS-2 did not improve the percentage of patients who survived to reach the hospital (22.8 percent LUCAS-2 vs. 23.3 percent manual), in whom pulse and breathing was restored (31.6 percent LUCAS-2 vs. 31.4 percent manual), and whose brain function after the event was good enough to allow them to live independently (4.7 percent LUCAS-2 vs. 6.0 percent manual).

"On the basis of ours and other recent randomized trials . . . the evidence available suggests this does not improve survival," lead author Dr. Gavin D. Perkins, Warwick Clinical Trials Unit, University of Warwick, Coventry, UK, concluded.  However, Dr. Perkins noted that use of a mechanical CPR device retains practical advantages such as safety and quality of CPR in the back of a moving vehicle and when transferring a patient to the emergency department. 

Based on these results, the researchers do not recommend the routine use of LUCAS-2 as a substitute for manual chest compression.

Funding for the study was received from National Institute for Health Research.