Effect of real-time feedback during cardiopulmonary resuscitation outside hospital: prospective, cluster-randomised trial

Abstract

Objective: To investigate whether real-time audio and visual feedback during cardiopulmonary resuscitation outside hospital increases the proportion of subjects who achieved prehospital return of spontaneous circulation.

Design: A cluster-randomised trial.

Subjects: 1586 people having cardiac arrest outside hospital in whom resuscitation was attempted by emergency medical services (771 procedures without feedback, 815 with feedback).

Setting: Emergency medical services from three sites within the Resuscitation Outcomes Consortium in the United States and Canada.

Intervention: Real-time audio and visual feedback on cardiopulmonary resuscitation (CPR) provided by the monitor-defibrillator.

Main outcome measure: Prehospital return of spontaneous circulation after CPR.

Results: Baseline patient and emergency medical service characteristics did not differ between groups. Emergency medical services muted the audible feedback in 14% of cases during the period with feedback. Compared with CPR clusters lacking feedback, clusters assigned to feedback were associated with increased proportion of time in which chest compressions were provided (64% v 66%, cluster-adjusted difference 1.9 (95% CI 0.4 to 3.4)), increased compression depth (38 v 40 mm, adjusted difference 1.6 (0.5 to 2.7)), and decreased proportion of compressions with incomplete release (15% v 10%, adjusted difference -3.4 (-5.2 to -1.5)). However, frequency of prehospital return of spontaneous circulation did not differ according to feedback status (45% v 44%, adjusted difference 0.1% (-4.4% to 4.6%)), nor did the presence of a pulse at hospital arrival (32% v 32%, adjusted difference -0.8 (-4.9 to 3.4)), survival to discharge (12% v 11%, adjusted difference -1.5 (-3.9 to 0.9)), or awake at hospital discharge (10% v 10%, adjusted difference -0.2 (-2.5 to 2.1)).

Conclusions: Real-time visual and audible feedback during CPR altered performance to more closely conform with guidelines. However, these changes in CPR performance were not associated with improvements in return of spontaneous circulation or other clinical outcomes. Trial Registration Clinical Trials NCT00539539.

Conflict of interest statement

Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/COI_disclosure.pdf (available on request from the corresponding author) and declare that 1) all authors have support from the listed funding agencies for the submitted work; 2) financial relationships with companies that might have an interest in the submitted work (DH, CWC, TDR, and GN received funding from Laerdal Medical or the Laerdal Foundation for Acute Medicine, CWC holds a patent related to defibrillation currently licensed to Medtronic ERS, TDR has received funding from Philips Healthcare, GKS holds stock in the Medtronic Corporation and is the inventor on two patents related to implantable defibrillators, assigned to Boston Scientific, GN has received research funding from Baxter and the Medtronic Foundation and is a research collaborator with Gambro Renal (Lakewood, CO), Sotera Wireless (San Diego, CA), and Lifebridge Medizintechnik AG (Ampfing, Germany), GN and CWC are compensated by the American Heart Association as committee chair, co-chair, member of affiliate board of directors, or worksheet reviewer); 3) no other relationships or activities that could appear to have influenced the submitted work.

Figures

Fig 1 Flow of subjects through the trial

Fig 2 Frequency distribution of the rate, fraction, and depth of chest compressions and the percentage of chest compressions with incomplete release during cardiopulmonary resuscitation stratified by whether monitor-defibrillators provided real-time feedback (“feedback-on”) or not (“feedback-off”)