NEW YORK (Reuters Health) – Use of mechanical cardiopulmonary resuscitation devices (mCPR) for out-of-hospital cardiac arrest was associated with less favorable neurologic outcomes than manual CPR in a recent analysis.

“The use of mCPR to deliver CPR has become more widespread, although a survival advantage has not been demonstrated in randomized, controlled trials. Little is known about real-world use of mCPR or the association with outcomes,” write Dr. Joseph Rossano of Children’s Hospital of Philadelphia, Pennsylvania and colleagues in Circulation, online December 19.

To investigate, the team analyzed registry data from 2013 to 2015 on 80,861 individuals (median age, 62) who experienced nontraumatic out-of-hospital cardiac arrest, 35.1% of whom received bystander CPR. Researchers compared outcomes for those treated with mCPR (17,625) and those receiving manual CPR only (63,056).

Although time of cardiac arrest, time of first CPR, and timing of the interventions were not reliably reported for all participants, information was available for return of spontaneous circulation – whether it occurred before or after advanced life support measures were initiated.

Compared with patients receiving manual CPR, those receiving mCPR were more likely to have had an unwitnessed cardiac arrest (57.3% versus 55.7%), placement of an automated external defibrillator (33.3% versus 28.3%), placement of an advanced airway (87.4% versus 79.0%), use of an impedance threshold device (41.8% versus 13.4%) and prehospital targeted-temperature management (16.6% versus 12.2%) (P<0.05 for all).

The team also looked at EMS agency use of mCPR during the study period. Overall, use of mCPR increased from 20.6% to 23.4% (P<0.0001), and mCPR was used at least once by 41.9% (244 of 582) of agencies included in the study. Median mCPR use was 43.9% for agencies that used the devices. However, agency use varied greatly, with 21.7% of agencies using mCPR in more than 75% of cardiac arrests and 37.7% using mCPR in fewer than 25% of arrests. Survival to hospital discharge was greater in patients not receiving mCPR (11.3% versus 7.0% for overall survival, P<0.0001), as was neurologically favorable survival (9.5% versus 5.6%, P<0.0001).

A subgroup analysis that assessed neurologic outcome at hospital discharge excluded patients with a return of spontaneous circulation before advanced life support, because those patients were less likely to receive mCPR. After that exclusion, the likelihood of a neurologically favorable outcome was also greater in those not receiving mCPR (5.9% versus 4.6%; P<0.0001).

Overall survival and neurologically favorable survival were greatest in EMS agencies that never used mCPR compared with those that used mCPR either in fewer than 25% of cases or in 25% to 50% of cases. No significant difference was found in agency survival percentages for those that just did manual CPR and for those that used mCPR in 50% to 75% of cases and more than 75% of cases.