They can help increase your chance of surviving a cardiac arrest by 75 per cent, but a shocking number of Canada’s Automatic External Defibrillators (AEDs) may be inaccessible to the public during an emergency because they are locked away or not registered with 911 personnel.

A CBC Marketplace investigation found that the potential for AEDs to save lives may be severely hampered because there are no national guidelines as to how or where the devices are kept.

There’s also no government requirement that they be registered with 911. Registering devices helps 911 dispatchers direct people to the closest AED in case of an emergency.

Watch Marketplace Watch Marketplace's episode, Shock to the System, Friday at 8 p.m. (8:30 p.m. in Newfoundland and Labrador). Join the conversation on Twitter @cbcmarketplace #defibs

About 40,000 Canadians experience sudden cardiac arrest each year: one every 12 minutes, according to the Heart and Stroke Foundation.

Eighty-five per cent of cardiac arrests in Canada happen outside of hospitals, and having an AED close by can make all the difference. The American Heart Association warns that for every minute lost before defibrillation, the survival rate decreases by seven to 10 per cent. After 12 minutes, the survival rate plummets to less than five per cent.

When CPR and an AED are both used within five minutes of a cardiac arrest, the chance of survival rises by nearly 75 per cent, according to research published in the Journal of the American College of Cardiology.

However, according to one study, fewer than eight per cent of Canadian patients who have a cardiac arrest in public will receive help from an AED before emergency medical personnel arrive, partly because there aren’t enough devices available and accessible.

Toronto police officer Laurie McCann, right, used a difibrillator on runner Andrew Rosbrook, left, after Rosbrook collapsed during a Toronto marathon in 2013. (CBC)

“People who have cardiac arrest in public settings tend to do better,” Dr. Laurie Morrison, a medical researcher who specializes in emergency medicine, told Marketplace co-host Tom Harrington. “At least somebody gets down and starts chest compressions and somebody else calls 911, and somebody else runs and get the AED.

“So having a cardiac arrest in a public place and not having an AED is a travesty,” she said.

The full Marketplace report, Shock to the System, airs tonight at 8pm (8:30pm NT) on CBC Television.

Devices difficult to find

Toronto police officer Laurie McCann knows first-hand how important it is to have fast access to an AED in an emergency. She was on duty at a marathon in Toronto in 2013 when runner Andrew Rosbrook collapsed.

“I knew he wasn’t breathing and we needed to do something fast,” she said.

“There were no warning signs, no chest pains,” said Rosbrook. “I considered myself to be a healthy person.“

“The defibrillator was put on and with one shock, he was brought back,” McCann said.

Both credit an easily accessible AED for saving Rosbrook’s life.

The pair helped Marketplace investigate how difficult AEDs can be to find.

Marketplace sent teams to locate AEDs in three areas of Toronto known to be “hotspots” for cardiac arrests according to a study published this year in the journal Circulation.

In total, the Marketplace teams visited 52 locations including gyms, banks, offices, coffee shops and malls. The teams chose places where a bystander might run to get help in an emergency, or where there were high concentrations of people. Only half of the locations had AEDs.

Security staff in many buildings did not immediately know if there was an AED on site. In buildings that did have the emergency devices, many were locked away or accessible only by building personnel, or were not registered with 911, meaning that dispatchers would be unable to direct people to them in case of an emergency.

Half of the AEDs that Marketplace teams found were not registered with 911.

“Scary, isn't it?” said Morrison. “It should be that [if you] purchase one of these devices, you couldn't put it in a building or public place without registering [the AED],” she said.

The Marketplace test is similar to defibrillator “scavenger hunts” in Seattle and Philadelphia that have helped those cities map the locations of devices. The Seattle hunt, which took place this week, offered a $10,000 US prize to the winning team, funded by the Food and Drug Administration and AED manufacturers.

No central registry

While provincial, federal and private funding is sometimes available to increase the number of AEDs in publicly accessible spaces, regulations and policies vary greatly across the country. There are no national guidelines on AEDs or central registry of devices.

Earlier this year, Prime Minister Stephen Harper announced a $10 million initiative to purchase AEDs for recreational facilities and hockey rinks across Canada, all of which will have to be registered with emergency personnel where local or provincial registries exist.

The Ontario government has committed almost $10 million to placing the devices in publicly funded sports and recreation facilities, and in schools with extensive sports programs.

Manitoba passed legislation earlier this year that mandates that designated public spaces, including schools, government buildings, malls and homeless shelters, have AEDs and that all devices are registered. Manitoba is the only jurisdiction that mandates that all public places have AED devices, a law that goes into effect in January 2014.

Ontario proposed a similar law in 2010, but while it passed second reading with unanimous support, the bill died when government was prorogued in 2011.

Morrison says that registration of all devices should be mandatory across Canada. The Heart and Stroke Foundation has been pushing for the creation of a national registry.

Morrison was part of a group of researchers from University of Toronto, St. Michael’s Hospital and Queen’s University that looked to cardiac arrest locations to assess where AEDs should be placed.

Their study, published earlier this year, identified unregistered AEDs as a problem. “A 911 operator would not be able to direct a caller to an unregistered AED, and therefore the likelihood that it would be used in a cardiac arrest is probably low, even if it is nearby. Unregistered AEDs tend to be purchased corporately and remain under lock and key,” the study reads.

The study states that in order to be effective, AEDs should be within 100 metres of the scene of a cardiac arrest, so a bystander is able to retrieve it and return within three minutes.

“The most meaningful thing out of that study for me was how little we know about the AEDs that are out there,” Morrison said.