How Local Data Analysis Might Boost Cardiac-Arrest Survival Rates

Mark Skalny/

When Jeffrey Hammerstein started as a paramedic in the 1980s, the likelihood of cardiac-arrest patients surviving was extremely low, not just in Wake County, North Carolina, where he still works, but anywhere in the nation.

Standard guidelines for cardiopulmonary resuscitation (CPR) suggested that paramedics only perform the procedure for about 25 minutes, a guideline that is followed by emergency medical technicians across the nation today.

But there was anecdotal evidence where a patient’s pulse would return when chest compressions were continued for a longer period of time when the patient showed some minimal signs of cardiac activity. Hammerstein, currently the district chief of community outreach for the county’s emergency management services, noticed that phenomenon locally, too.

“Then all of a sudden at the 45-minute level we’d have a pulse back,” Hammerstein said in a recent interview where he recounted the timeline of how the county began analyzing local EMS data with results that eventually could help change the way paramedics across the nation respond to cardiac-arrest patients.

“The first half of my career, with a cardiac arrest, nobody survived, with very rare exceptions,” he said. “Then that really started to change in the 2000s, when we changed the way we did resuscitation.”

Wake County paramedics, who respond to about 500 cardiac-arrest calls annually, began performing CPR for longer periods of time. “We started to get pulses back on those cases,” he said. “That’s where it started to translate where we got more people who were surviving.”

But was there a firm connection between the length of time chest compressions were performed and survival rates?

Through a comprehensive data-analytics project, Wake County Emergency Medical Services, with the help of SAS Advanced Analytics Lab for State and Local Government, collected data from county cardiac-arrest responses from 2005 to 2012 and looked at patient outcomes.

They found that if Wake County paramedics had continued under the 25-minute guideline from 2005 to 2012, 100 people, who ultimately left the hospital, would have died.

As a result, Wake County changed its CPR recommendations to encourage paramedics to continue the procedure beyond the 25-minute mark if the patient has not already flatlined. In patients where there are some minimal signs of cardiac activity, paramedics may continue CPR for up to an hour without worrying about the additional risk that patients will end up in a vegetative state.  

“Through the ’80s and into the ’90s, we looked at cardiac-arrest patients as not survivable. Now we don’t look at that [person] as a dead person,” Hammerstein said. “We haven’t written them off.”

Wake County’s cardiac-arrest findings were presented in January to the National Association of EMS Physicians, which named the county EMS’s paper as the “Best EMS Professional Research Presentation.”

The national EMS community has taken notice but they’re waiting to see the full version in manuscript form,” said Wake County EMS Deputy Medical Director Jefferson Williams.

While data-collection and analysis is important in the emergency medicine field, Wake County is very proactive, Williams said. “We’re fortunate with our resources in Wake County. We make sure [the data are] clean and appropriately entered,” he said.

But to get a full grasp on the cardiac-arrest data, the county needed the expertise of SAS, based in Cary, just outside Raleigh.

“To do something like this it takes a lot of time to get it into an analytical form,” Williams said.Williams said that Wake County, home to the state capital, was an ideal place to tackle a project like this because of its size.

“We’re big enough to measure but small enough to change,” he said. “In other communities that are very large, implementing change in practice can take a lot of time."

In the near term, Wake County will be working to put its cardiac-arrest findings in manuscript form so peer EMS organizations can study them more closely.

“By practicing evidence-based medicine, guided by data, many Wake County residents are alive today who wouldn’t have been,” said Dr. Brent Myers, the director of Wake County EMS.

“Our recognition at the annual meeting gives us hope that our approach will be replicated by other EMS groups around the country, and save more lives.

”But it will require more time and study to see if the discoveries in Wake County, which now has a 16 percent survival rate for cardiac-arrest patients—roughly double the national average—will change the way the rest of the nation approaches emergency medical response.

“The 30,000 foot view is that we still have a long way to go here,” Williams said.

(Image via Mark Skalny/


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