Babbage | Medical technology

Crowdsourcing good Samaritans

An app tries to get passers-by to help in medical emergencies

By M.H. | SEATTLE

AUTOMATIC external defibrillators (AEDs) are a common sight in America, where many states now require them at fitness centres, schools or airports. These devices deliver potentially life-saving electric shocks to victims of sudden cardiac arrest, a condition that claims 300,000 American lives each year, more than AIDS and lung, breast and prostate cancers combined.

AEDs have the best chance of working if action is taken promptly in the event of an emergency. The probability of survival decreases by 10% for every minute of hesitation, and by 5% even if cardiopulmonary resuscitation, better known as CPR, is performed. But even though America is home to over 1.5m public AEDs, they are used in fewer than one in twenty sudden cardiac arrests that occur outside hospitals. In many cases, there are no AEDs in the immediate vicinity. Often, though, bystanders either do not realise that somebody is experiencing a cardiac arrest, cannot find an AED, or do not know they should be looking for one. Partly as a result, the survival rate for such incidents is the same today as it was two decades ago: a shocking 8%. By the time trained paramedics, with their own AEDs, arrive on the scene, most victims are irredeemably deceased.

Now a small fire department in California is tackling all three problems with a smartphone app which relies on the idea of crowdsourcing. When someone reports a sudden cardiac arrest in the San Ramon Valley, 30 miles (48 km) north of San Jose, the fire department immediately dispatches an ambulance. It simultaneously sends out an alert to users of its iPhone app, showing directions on a digital map to both the victim and the nearest public AED. The app uses geo-location to alert only those people within 500 feet (160 metres) of the incident—in other words, those who may be able to get to the sufferer those crucial minutes ahead of the paramedics.

The system went live this summer and already has 40,000 active users. So far it has been activated just once, after someone exercising at a local gym collapsed. Eight citizens were alerted, two responded and a nearby AED was put into action. The patient survived. The app, which was developed entirely using local taxpayer's money and is free to download, has since attracted wider attention. The cities of San Jose and San Francisco are now planning trials of the technology, as is the state of Arizona. New Zealand is hoping to be the first country to deploy it nationwide.

Of course, such apps are only as good as the AED databases they rely on. California requires owners of public AEDs to register their devices but other states do not. Even in the Golden State, though, not all organisations comply. Moreover, few emergency services will have sufficient resources to check that all public AEDs are accessible, in good condition and ready for use.

Raina Merchant, of the University of Pennsylvania, believes that crowdsourced Good Samaritans can help here, too. She is about to launch a project that uses another smartphone app to plot the locations of Philadelphia's public AEDs. The app, called MyHeartMap Challenge, encourages people to take geo-tagged pictures of public AEDs in their neighbourhood and note details such as their colour and manufacturer. Philadelphia may be Greek for "brotherly love", but Dr Merchant is not counting solely on its citizen's warm-hearted do-goodery. The individuals and teams who capture the most devices during the Challenge this winter will earn cash prizes of up to several thousand dollars.

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