Herd immunity to cardiac arrest
the resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, especially through vaccination.
Keeping this concept in mind, consider this: The American Heart Association reports that over 350,000 people die each year in the United States due to cardiac arrest. Worldwide, the figure is a staggering 1.3 million. Though not a contagious disease, it is solidly the #1 leading cause of death for adults in the developed world.
Another 'contagious' trend in the developed world is mobile phone ownership. A Pugh Research report from 2015 shows that over 90% of adults in the US own cell phones, 68% of which are 'smart phones.' That works out to be around 288 million phones for the US population of around 320 million people. In other words, there are over 820 cell phones per cardiac arrest in the US population.
Question: Where is a good place to put an AED (automated external defibrillator)? It needs to be somewhere handy, and there need to be lots of them around, particularly where there are lots of people. Yes, mobile phones! More specifically, the technology for an AHD could be miniaturized and put into a phone case so that it would be carried with a mobile phone.
This is an incredibly valuable idea, and could be a powerful saver of lives. Consider that, if only 4% of Americans owned an AED cell phone case - nearly 1 in 30 Americans would have one in their pocket. If you happened to have a cardiac arrest on a bus or a ball game, or on a city street, there would be a very good chance someone would save your life. Persons with preexisting cardiac conditions would be even more likely to own one. Smart phones enabled with AEDs would also be able to alert medical help, sound an alert, and would be able to issue visual & verbal instructions for use. If implemented this would be a wonderful example of technology being at the right place at the right time.
I did some cursory checking, and there are in fact some patents and even crowdfunding campaigns out there intent on making AED cell phone cases. To date, I have not found any products on the market, but that is unsurprising. Technology takes time to bridge that often vast gulf between concept and product. Some ideas - even very good ones - die in the development phase. I think this idea, in particular, deserves to be watched and shepherded into existence.
Heart image by Patrick J. Lynch, medical illustrator - Patrick J. Lynch, medical illustrator CC BY 2.5