This randomized clinical trial examined whether a device that measured and provided feedback on CPR to paramedics would improve delivery of CPR and result in better patient survival after cardiac arrest.
Cardiopulmonary resuscitation (CPR) consists of chest compressions and artificial breathing. CPR is essential for survival after cardiac arrest (when the heart stops beating). After more than a few minutes of cardiac arrest, irreversible brain damage and damage to other organs can occur. With high quality CPR, patients may endure many minutes of cardiac arrest until emergency providers can restart the heart.
High quality CPR requires that chest compressions be performed with good depth (more than 2 inches), good rate (about 100 compressions per minute) and without interruptions. While paramedics are performing advanced life support, a variety of tasks may distract from CPR.
This trial used a monitor that can measure chest compression depth, rate, interruptions and breaths delivered. The machine has the ability to provide feedback (alarms and voice prompts) when it detects interruptions in CPR or decreases in CPR quality.
In this trial, 1556 subjects who were treated for cardiac arrest by first responders and paramedics were studied. Paramedics carried the same monitors. About one-half of the monitors had the voice and alarms turned on. These cases received feedback about CPR during the resuscitation. The other half of the monitors recorded CPR information, but did not provide alarms or voice prompts about CPR. These cases received "no feedback." Investigators reviewed the medical records for each subject to determine if they survived to leave the hospital. Investigators also reviewed the CPR performed by the paramedics in each case.
Having feedback increased the average depth of chest compressions (deeper by ~2 mm), increased the percentage of time chest compressions were performed (from 62% to 64%), and reduced the average rate of chest compressions (107 to 103 per minute). These changes were small in part because even paramedics with "no feedback" provided CPR that was very close to the recommended rate, depth and timing.
There was no detectable difference in the proportion of patients with feedback or without feedback who regained pulses (44% versus 45%), who survived at least one day (29% versus 28%), or who were discharged awake from the hospital (10% versus 10%).
This study concluded that CPR feedback can increase the likelihood that CPR will be performed in the manner recommended. However, this effect did not alter patient outcomes in a setting where paramedics already do good CPR and already have excellent patient outcomes.
Hostler D, Everson-Stewart S, Rea TD, Stiell IG, Callaway CW, Kudenchuk PJ, Sears GK, Emerson SS, Nichol G; Resuscitation Outcomes Consortium Investigators. Effect of real-time feedback during cardiopulmonary resuscitation outside hospital: prospective, cluster-randomised trial. BMJ. 2011 Feb 4;342:d512. doi: 10.1136/bmj.d512.
View the CPR Feedback Study Press Release