CPR performance improved, though return of pulses and survival to discharge did not
Emergency medical service (EMS) providers in the United States assess an estimated 350,000 cardiac arrests each year. Only 5 to 10 percent of people who have sudden cardiac arrest survive. Better quality cardiopulmonary resuscitation (CPR) provided by prehospital EMS providers may be associated with better patient outcome. The Resuscitation Outcomes Consortium (ROC) is the largest clinical research network to study prehospital treatments for cardiac arrest in the United States and Canada. ROC conducted the first randomized study to assess if real-time audio-feedback, during the EMS prehospital course of care, would improve clinical outcome. Results of the study were presented on November 15th during the Resuscitation Science Symposium 2009 program.
Twenty-one EMS agencies from three ROC regions in the US and Canada (King County, WA; Pittsburgh, PA; Thunder Bay, ON) enrolled 1,521 treated non-traumatic cardiac arrest patients over the course of 25 months. The study included all eligible patients who received EMS rescue shocks or chest compressions. Participating agencies were provided by the manufacturer with commercially available devices equipped with visual and audible real-time feedback coaching the quality of CPR. Agencies provided training to their EMS providers in a manner consistent with local policy and standards.
In this prospective randomized trial, EMS agencies were assigned to one of two treatment groups, audible 'feedback on' or 'feedback off.' When feedback was on, real-time audible and visual prompts advised providers to conform CPR to American Heart Association (AHA) guidelines. The assignment changed every two to seven months, depending on the expected number of treated cardiac arrests. When assigned to 'feedback on,' EMS providers muted the audible coaching in 15% of cases. Baseline characteristics of patients randomized to each of the two groups were comparable.
The primary objective of the study was to determine the proportion of patients with a return of spontaneous circulation (ROSC) during the prehospital course of EMS care. ROSC was defined as the presence of a palpable pulse in any blood vessel for any length of time. The difference observed between the two study groups was not statistically significant: return of spontaneous circulation occurred in 48.0% of 'feedback on' and 48.8% with 'feedback off.'
Secondary outcomes of the study were also reported: