Saturday, May 5, 2018

CPR with Strangers on a Train

I'm a long-time reader of Discover magazine, and consistently my favorite item is the Vital Signs column. It's my chance to vicariously experience the career I never had in medicine, and particularly diagnostics. The stories are always in first person, retelling a case the author was involved in treating.

This month's column is by Tony Dajer, who has been a frequent writer over the years and is now the head of emergency medicine at New York-Presbyterian. The story starts on a subway train when someone calls out, "Is there a doctor on the train?"

Well, it turns out there were three doctors and an ER nurse on the train, which came in handy when they had to do CPR for a while as the train stopped, then made its way to the platform where it was met by EMTs. They took turns compressing a man's chest 100 times a minute.

The article is focused on the realities of CPR: how the American Heart Association in 2008 announced that mouth-to-mouth resuscitation no longer was needed, how hard it is to maintain accuracy and pressure over time, and that in general CPR is not the panacea most of us think it is, based on how it's portrayed in media. I already knew most of that, but here are the facts I never had heard before:

  • CPR generates only a third of the heart's regular output of oxygenated blood.
  • Every minute that goes by before defibrillation, the odds of survival decreases 10 percent. 
  • 360,000 people in the U.S. experience sudden cardiac arrest every year and fewer than 10 percent of them survive. (Hence the proliferation of AED machines in public places.)
  • That 90 percent who don't survive die because they lacked oxygen to the brain.
  • The reason CPR works at all is because when you're in cardiac arrest, your body shuts down most of its other requirements, and your brain only needs 20 percent of the heart's output, so the 30 percent available from CPR is plenty to keep the brain oxygenated.
The patient in this case survived with no brain damage, and received an implantable AED just to rule out future arrests. And I learned more about CPR than I ever knew.

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