Dr. Laurie Morrison
Walking through an office building on St. George Street in downtown Toronto, Christopher Sun – a PhD candidate in engineering – spotted a portable automated external defibrillator, conveniently located by the building entrance.
From 8 a.m. to 9 p.m., its accessibility could be vital in saving a life. However, after 9 p.m. when the building closes, it’s almost as if the AED isn’t there.
One out of every five cardiac arrests that occur within 100 metres of an automatic external defibrillator, or AED, happens when that device is not accessible because the building is closed. Many AEDs are placed in buildings without 24-hour access, such as offices, schools and recreation facilities.
Researchers at the University of Toronto and St. Michael’s Hospital have studied the times when publicly located AEDs are available and cross-checked them with the 2,440 out-of-hospital cardiac arrests that occurred in Toronto between 2006 and 2014. They presented the findings today at the American Heart Association conference in Orlando, Fla.
They found that 451 of the 2,440 out-of-hospital arrests were assumed to have 24-7 access to an AED, but only 354 were actually accessible at all times, representing an overall 21.5 per cent decrease in access when time of day and building hours were considered. Broken down by time of day, access decreased by more than eight per cent during daytime hours, 28 per cent in the evening and 48 per cent at night. More than 60 per cent of out-of-hospital cardiac arrests occurred during evenings, nights and weekends, when AED accessibility decreased the most.
“Previous work has focused almost entirely on location or spatial factors,” said Sun, a co-author of the study. “Time factors, such as when cardiac arrests occur and the time of day, have been largely overlooked.”
The greatest decreases in AED accessibility when cross-checked with time were found in schools, industrial buildings, recreation facilities and offices (39.7, 39.3, 37.1 and 35.5 per cent, respectively), all of which have limited hours on evenings and weekends. Transportation facilities and locations that operate close to 24 hours a day were less affected.
“This gap in coverage can be the difference between life and death,” said Dr. Laurie Morrison, an emergency medicine specialist at St. Michael’s and collaborator in the research. “However, emergency medical services and investigators are united and willing to reposition AEDs to locations that are accessible.”
Dr. Morrison heads Rescu, the largest research team of its kind in Canada dedicated to improving out-of-hospital resuscitation. This research was conducted for Rescu in collaboration with the University of Toronto to identify ways to improve access to AEDs in out-of-hospital situations. “If you have a cardiac arrest, every second counts,” said Dr. Morrison. “Out-of-hospital cardiac arrests kill an estimated 300,000 people in North American annually.”
To address this issue, the researchers have developed an approach to optimize AED accessibility for cardiac arrests by installing them in more areas with 24-hour access. The model also takes time of day and day of the week into consideration for ideal AED locations.
“Our research has shown AED availability for cardiac arrests is overestimated when time factors, such as building access and time of day, are not considered,” said Dr. Timothy Chan, an engineering professor at the University of Toronto. “The model considers time of day, building access and location information to optimize AED availability. Using the model, we found an average 25 per cent improvement in AED accessibility for cardiac arrests at all times of day.”
In addition to the overall improvement in AED availability, the optimizing model showed 11 per cent better access during the day, 38 per cent in the evening and 123 per cent at night.
“This research will be beneficial for developing policies and guidelines for AED placement across the world, and ultimately help save more lives,” said Chan.
This paper is an example of how St. Michael’s Hospital is making Ontario Healthier, Wealthier, Smarter.
About St. Michael’s Hospital
St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael’s Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.
About University of Toronto Engineering
Founded in 1873, U of T Engineering has approximately 5,200 undergraduate students, 1,950 graduate students and 240 faculty members. U of T Engineering is at the fore of innovation in engineering education and research and ranks first in Canada and among the top Engineering schools worldwide.
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