The drones beat the ambulances handily, according to a report published Tuesday in the Journal of the American Medical Association. In all 18 cases, the drone arrived more quickly than the ambulance had.

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The best medicine for a person who goes into sudden cardiac arrest is an electric shock. That jolt temporarily stops the heart, along with its rapid or erratic beat. When the heart starts itself up again, it can revert to its normal rhythm and resume pumping blood to the brain and the rest of the body.

The sooner this happens, the better. When a patient is shocked within one minute of collapse, the chance of survival is nearly 90 percent. But if it takes 10 minutes to administer a shock, the odds of survival fall below 5 percent.

If a victim is lucky, he’ll collapse in a mall, airport, school or other public venue that’s outfitted with an automated external defibrillator, or AED. These user-friendly machines can assess the cause of cardiac arrest, determine whether a shock is appropriate and deliver it if necessary.

If a victim is unlucky, he’ll have to wait for an AED to come to him. Usually, this means calling for an ambulance. But in the not-too-distant future, the ambulance could be replaced by a flying drone.

If that sounds ridiculously futuristic, head over to the Karolinska Institute in Stockholm, Sweden. That’s where a team of doctors and nurses built a bright-yellow drone capable of delivering an AED to a patient in need.

The drone weighs about 12.5 pounds and uses eight rotors to achieve speeds of up to 47 mph. Once a pilot programs its route and destination, the drone uses a GPS system, autopilot software and a high-definition camera to get there. Fluorescent paint and LED lights help make it easy for people to find.

Members of the research team had previously used geographic-information-system data to estimate whether there would be any advantage to putting AEDs on drones. Their models suggested that a drone would arrive faster than an ambulance 93 percent of the time, saving patients an average of 19 minutes.

Now they’ve gone a step further and dispatched a drone from a fire station about 45 minutes north of Stockholm to 18 locations where people suffered cardiac arrests away from a hospital between 2006 and 2014. The times for the test flights were compared with the ambulance times recorded in the Swedish Registry for Cardiopulmonary Resuscitation.

As predicted, the drone beat the ambulances handily, according to a report published Tuesday in the Journal of the American Medical Association. In all 18 cases, the drone arrived more quickly than the ambulance.

The time it took to get the drone dispatched, launched and to the site of a cardiac arrest ranged from a low of 1 minute, 15 seconds to a high of 11 minutes, 51 seconds. Ambulances had taken between 5 minutes and 38 minutes to respond to calls at the same locations.

For the drones, the median time from dispatch to arrival was 5 minutes, 21 seconds. For ambulances, it was 22 minutes. Thus, the median amount of time saved by drones was 16 minutes, 39 seconds.

“Saving 16 minutes is likely to be clinically important,” the study authors wrote.

The American Heart Association estimates that in 2016, more than 350,000 people in the United States went into cardiac arrest away from a hospital; only 12 percent of them survived long enough to be treated in a hospital and released. With so much room for improvement, drones have the potential to make a real difference.