A study published this week in the New England Journal of Medicine has shown that an automated, mobile phone based system can help get critical early CPR to patients with an out-of-hospital cardiac arrest.

In the United States, there are over 400,000 out-of-hospital cardiac arrests each year. Early and effective CPR is critical for these patients. An observational study from Sweden, also in this weeks NEJM, found a significant difference in 30-day survival based simply on whether or not the patient got CPR before EMS arrived (10.5% vs. 4%, p<0.001).1

Researchers in Sweden tested out a system designed to help improve the delivery of early bystander CPR by engaging good samaritans through their mobile phones.

Ringh and colleagues started by recruiting volunteers trained in CPR from, for example, CPR classes. These volunteers registered online and provided their cell phone numbers.2

When a suspected cardiac arrest call came in to the emergency response center, calls were randomized to either usual care or usual care plus the mobile phone based volunteer notification system. Basically, the system checked to see if there was a volunteer within 500 feet of the arrest location. If so, an automated call and text message went out to the volunteer with information on the call including location.

By the end of the study, nearly 10,000 volunteers had signed up. A little over 600 patients were inclined, about 300 in each group. Of the 306 patients in the intervention group, 81% of patients had a trained volunteer within 500 ft at the time of their arrest. And in those instances where there was a trained volunteer nearby, one of those volunteers tried to get to the patient more than 75% of the time.

In the end, this resulted in an increase in the rate of bystander CPR from 48% to 62% (p<0.001); in the adjusted analysis, the chances of receiving bystander CPR increased by 70% with the mobile phone based activation system.

There are several notable points worth taking away. First, the uptake and engagement of volunteers was impressive – not only did nearly 10,000 people sign up, but when activated a majority tried to respond. Second, while the study wasn’t powered for outcomes like survival, the magnitude of the effect (a 14% improvement) could actually be meaningful enough to make a real difference.

In the accompanying editorial, Dr. Comilla Sasson and Dr. David Magid highlight some limitations, particularly when it comes to the United States.3 First, we don’t have the centralized emergency response system that Sweden does so deployment on a large scale would be tricky. That said, use in more densely populated cities may be feasible. They also point out that volunteers here may be deterred by our more litigious society. That’s a fair point but probably less of an issue in places with solid Good Samaritan laws.

Bystander CPR can be critical to survival when someone arrests outside of the hospital. As we invest in public health efforts to train people in CPR, it makes sense to also think about ways to get these potential lifesavers to the places they are needed. Given that almost all of them have a mobile phone in their pockets, the system proposed by Ringh and colleagues is a practical, relatively low cost way to potentially make a big impact.