Flying Defibrillators

It’s a sad reality that, by and large, cardiopulmonary resuscitation (CPR) doesn’t save lives. Despite all the “you could save a life” marketing aimed at getting people certified in CPR, the instances where even the prompt application of the correct technique results in a save are vanishingly rare, and limited mostly to witnessed arrests in a hospital. Speaking from personal experience, few things are sadder than arriving on-scene as a first responder to see CPR being performed by a husband on his wife and knowing that no matter what we do, it’s not going to end well.

The problem is one of time. Hearts only rarely just stop beating outright; usually some kind of arrhythmia first causes the heart to beat ineffectively, leading to hypoxia and loss of consciousness. From there it’s about a four-minute trip to brain death, but in that brief window chances are pretty good that the heart can be restarted. That’s why witnessed cardiac arrests in a hospital have better survival rates — the needed electric reboot of the heart with a defibrillator is only as far away as the nearest crash cart.

The advent of the automatic external defibrillator (AED) has increased the odds for survival of out-of-hospital cardiac arrest (OHCA), but the penetration of AEDs into public settings is far from complete enough to put one within a few minutes reach of everyone who might need one. So it’s only natural that thoughts would turn to delivering AEDs to cardiac incidents by drones. It seems like a great idea, but will it work?

Current Research

This is not yet another “let’s stick something on a drone and call it innovation” effort. A team of researchers at the Center for Resuscitation Science at the Karolinska Institute in Stockholm have given this serious thought and have been running a serious test program geared toward seeing if drone-delivered AEDs show any clinical benefit. A preliminary study started with an analysis of OHCA events to find the optimum location to deploy a drone for testing, to ensure an ample data set. They then set up models using GIS data to perform a virtual race between terrestrial EMS crews and a drone. Finding that the drones would beat ground crews about 93% of the time in a rural setting, they then conducted piloted UAV test flights to test release methods for the AED. Releases from 25-meters with a parachute and low-altitude drops of just the AED were tested, as were releases from landed UAVs.

AED test drop. Source: Hjärtstoppscentrum

Their latest study, the full text of which sadly is behind a paywall, took the program a notch further by running fully autonomous flights to 18 rural locations where OHCAs had previously occurred. They simulated what the fully built-out system will eventually be capable of — a dispatcher uploads GPS coordinates to the drone based on information from the caller, and the drone is launched and flies to the incident autonomously. For safety UAV pilots monitored the launch and landing. They found significant improvements in response times — a median reduction of 16.5 minutes overall, with a mere three seconds from dispatch to launch compared to three minutes for a ground crew to get an ambulance on the road.

Despite the breathless coverage of this research in the popular media, drone-delivered AEDs are not about to happen anytime soon, at least not as far as the authors are concerned. They’re wisely taking baby steps toward something that seems like a great idea, but may end up offering no benefit and could possibly result in decreased survival rates. Whether this will result in improved outcomes in OHCA has yet to be tested, but given the dismally low 8-10% current survival rate, it’s hard to see how getting an AED on the scene in a few minutes can’t help improve the numbers.

The Problems

The main problems all revolve around the weak link in the system — the responder on the scene. The extremely simple user interface of modern AEDs can prove challenging to untrained Samaritans and may not be properly deployed in time to make a difference. Even with proper training, the stress of performing when a real person is dying in front of you can make you forget everything; add the fact that more often than not the victim will be a loved one of the responder and all bets on performance are off.

There are also technical hurdles — will an AED survive the rigors of flight? Will responders be injured by trying to retrieve the AED from a landed drone before the props spin down? What effect will weather have on timely delivery? All these questions need to be answered, and it looks like the Stockholm team has a good handle on all of this.

So when will fleets of aerial defibrillators begin plying the skies? Your guess is as good as mine, but I’ll bet that it won’t be anytime soon. All the testing being done in Sweden now will certainly move the ball downfield, but there will be huge regulatory hurdles to deal with before putting a system like this online. In the US alone, such a system would likely have to pass muster with both the FAA and FDA, and possibly the FCC if there are to be communications between the drone and the dispatch center for coaching. Getting one alphabet agency to sign off on a new technology is hard enough, but three? That might prove challenging.

But as it stands, aerial AEDs seem like they could become a reality someday, and they could prove to be yet another good use case for UAVs.

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