Drones Cut Response Time in Cardiac Arrest

Pauline Anderson

June 15, 2017

Delivering defibrillation using a drone — or an unmanned aerial system — can shave upwards of 16 minutes off the response time to an out-of-hospital cardiac arrest, new research suggests.

"Our study shows that people have the potential to survive, even at high rates, if we put a low-cost system into an existing infrastructure in areas with prolonged EMS [emergency medical services] response times," Andreas Claesson, RN, PhD, Center for Resuscitation Science, Karolinska Institutet, Stockholm, Sweden, told Medscape Medical News.

The research was published online June 13 as a research letter in JAMA.

According to the American Heart Association (AHA), more than 350,000 out-of-hospital cardiac arrests (OHCAs) occur annually in the United States, and only about 1 in 10 patients survive. Experts estimate that for every 1 minute that a patient is pulseless, the survival rate drops by 10%.

"Reducing time to defibrillation is the most important factor for increasing survival in OHCA," they write.

From a national registry, researchers gathered information on EMS response time for 18 consecutive cases of cardiac arrest that had occurred in one area of Sweden between 2006 and 2014. This area, popular during summer months, has a high rate of cardiac arrest and a "prolonged" time from arrest to arrival of EMS, said Dr Claesson.

Researchers simulated each of these emergency situations using a drone placed at a local fire station. The drone, weighing 5.7 kg, was equipped with an automated external defibrillator (AED), global positioning system (GPS), and high-definition camera and was integrated with an autopilot software system.

During a 72-hour period in October 2016, the drone was dispatched for out-of-sight flights to where the consecutive OHCAs had occurred, all within a 10-km radius of the fire station. The drone has a maximum cruising speed of 75 km/h.

The Swedish Transportation Agency granted flight permission.

Two licensed pilots sent the GPS coordinates and routes to the drone using alternating telemetry over a 433-mHz and 3G network, the researchers note. The entire flight was autonomous, monitored by the dispatcher, but for safety reasons, a second pilot was at the landing site in telephone contact with the dispatcher to manually take over the descent if necessary, they write.

The median time from dispatch to arrival of the drone, the primary endpoint of the study, was 5:21 minutes compared with 22:00 minutes for EMS (P < .001).

"We believe that a shock delivered within 5 minutes can result in a survival rate reaching at least 20% or 30%," although this has to be tested, said Dr Claesson.

The drone arrived more quickly than EMS in all cases, with a median reduction in response time of 16:39 minutes (95% confidence interval, 13:48 - 20:12; P < .001).

There were no technical issues or other adverse events during any of the flights, although the authors note that the number of flights was limited and that flights were over short distances and in good weather.

While the study simulated cases that occurred within 10 km from the fire station, the actual range of the drone is 20 km, said Dr Claesson. "And the range will be better in coming years."

The system still requires perfecting. For example, further test flights and technological development are needed, as is evaluation of integration with dispatch centers and aviation administrators, said the authors.

Further, researchers will have to determine how the dispatcher should interact with a bystander. For the system to work, a witness will have to detach and use the defibrillator and be willing to do cardiopulmonary resuscitation.  

In addition to delivering defibrillators, drones could have other uses in emergency situations where minutes count and geographic or structural barriers might prevent a timely EMS response. For example, they could be used to deliver adrenaline for patients with anaphylactic reactions or to deliver an opioid antidote.

And they could be used to locate missing persons, such as those buried in an avalanche. Dr Claesson and his colleagues published a study that looked at the use of a drone to locate a drowning victim simulated by a mannequin placed underwater.

"The drone could easily spot the 'victim' from 60 meters, and faster than lifeguards," said Dr Claesson.

He stressed that "this is a low-cost system" and that the technology "is here now."

Change Mindset

However, there are drawbacks to using drones for emergencies in the immediate future. For example, they currently have to follow predefined flight corridors.

Legislation pertaining to flying "out of sight" has to be updated, said Dr Claesson. "We have to change the mindset where manned aircraft is prioritized and unmanned aircraft is not really seen as something that is doing good."

Asked to comment on the research, Michael Christopher Kurz, MD, associate professor, Department of Emergency Medicine, University of Alabama at Birmingham, used words such as "amazing" and "exciting" to describe what he sees as a "technological revolution" where delivery of AEDs using a drone could soon become routine in some areas.

"It's a neat innovative way to use technology to combat a public health issue that we have been trying very hard to make a dent in for decades," he told Medscape Medical News.

Even if only half of the improvement in response time seen by the authors — over 16 minutes — could be achieved in "real life scenarios" where people are suffering cardiac arrest, "it would have a dramatic impact on the survivability by providing the lifesaving therapy that much quicker," said Dr Kurz, who is also chair of the American Heart Association Systems of Care Subcommittee of Emergency Cardiovascular Care Committee.

Defibrillators are already widely available in places like airports, arenas, schools, and other urban centers, but using drones to deliver this life-saving device "casts a wider net of public access," said Dr Kurz.

The drone may be particularly useful in rural areas, "where we have had a very difficult time with penetration," he said.

"This is a very exciting and interesting technological revolution and I suspect that a couple of years from now, we will be talking about how this is becoming routine in very forward-looking municipalities," he said.

The study was funded by the Stockholm city council innovation fund. Dr Claesson has disclosed no relevant financial relationships.

JAMA. Published online July 13, 2017. Abstract

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