Thursday, September 17, 2015

Eko the Electronic Stethoscope: A Failure to Comprehend the Rituals of Medicine

A glowing article on electronic stethoscopes recently appeared in the Chicago Tribune.  The Eko Core is a device which, "brings the power of modern technology to an already essential device. The implications could be huge for patient care."

I am no Luddite- I chose to attend USC for medical school because of it's Health, Technology and Engineering Program- to further my interests in engineering and building new devices while going through a full, rigorous medical education.  But it pains me to say that I suspect this is yet another overhyped device that does not fulfill a true healthcare need.  It has fallen prey to a common problem- a lack of deep understanding of medical science and practice by an engineering team seeking to provide an elegant solution to a perceived technical problem.



I must include a disclaimer: I may very well be entirely wrong- for a reason I will discuss at the very end.

The desire to build this device is understandable.  Every doctor has a stethoscope, and uses it seemingly all the time.  Why not build a better one so that they can hear sounds better?  It seems obvious.  That's because it is.  Electronic stethoscopes have been available for decades.  An article from over 20 years ago describes the comparison of an electronic stethoscope from 280 miles away to one listening live.

Some physicians do use them.  During my second year, I had an elderly but extremely competent physician preceptor who used one such device to compensate for hearing loss.  He picked up murmurs just fine.  But, they have never really caught on among the general pool of doctors.  Why is this, and why might Eko catch on now?  The article provides one explanation:

"While other electronic stethoscopes exist, Eko's is the first to have a federally compliant smartphone app, and integration into the electronic health record."

So, ultimately, is it just a matter of needing to integrate the findings into the computer system?  This doesn't make too much sense.  Phonocardiograms, a paper based depiction of murmurs, have been around for decades.  And besides, we have had computerized systems for decades- surely we could have figured out a way to electronically store sounds if we wanted to.

The real reason electronic stethoscopes have never fully caught on is something that medicine doesn't really publicize: the stethoscope is no longer really used as diagnostic tool for the heart.

The reality is that doctors were never that accurate when we used stethoscopes to listen to patients' hearts.  And since the development of so much technology, we've gotten worse.  A study from 2005 compared 1st year medical students with just 18 hours of training (basically someone who may have been guzzling beers at a frat party without a care in the world 2 months prior) using hand-held ultrasounds against board certified cardiologists (someone who had 10 years/~30,000 hours of back-breaking clinical experience) listening with a stethoscope.  How did they do?  If a patient had a lesion that produced a diastolic murmur, the students picked it up with ultrasound 75% of the time.  (Systolic murmurs may be benign in many cases, diastolic murmurs are generally more serious).  This seems pretty bad, until you read that the cardiologists picked it up by listening only 16% of the time.  For all possible cardiac lesions, the students picked up 75%, while the cardiologists got 49%.  This finding has been replicated, with this study being just one example.

If a doctor hears anything abnormal, or more likely if the patient complains of any symptoms of cardiac disease, the decision is the same- get an ultrasound of the heart, a test known as an echocardiogram.  Now, we may even be moving to the era when the family physician just looks at the heart with a hand-held ultrasound then and there.  Why would any physician buy and use an Eko when they will just order an Echocardiogram on anything suspicious?  They won't.  The article hints at this, but tries to justify it's laudatory treatment of Eko on cost grounds:

"Currently, a professor at the University of California-San Francisco is testing the algorithm to see how it stacks up against an echocardiogram, a trusted but expensive machine used to monitor the heart."

Echocardiograms are actually cheap as tests go, lack any radiation exposure, and are getting cheaper and better every day.  And I doubt that any attempt to listen to sounds that are modulated by fat, tissue density, heart position, flow dynamics, and a thousand other myriad factors will be as accurate as as an ultrasound device that looks at the heart.

So, if we are so bad at listening to the heart, why does every doctor carry one?  Well, for one it can be used to listen to the lung to look for pneumonia and to get a sense of whether patients with various diseases are over or under hydrated, though it soon may be proven that ultrasound is better at even this.

But more than that, it is a tool used in a ritual.

Dr. Abraham Verghese, MD, is a physician at Stanford who is world renowned for his desire to bring the human element back into medicine.  He would undoubtedly be horrified at my casual disparagement of the diagnostic value of listening to the heart above, as he has pioneered an initiative to improve physicians' physical diagnosis skills.  But in his seminal TED talk on rituals in medicine, he says something quite profound:

"
And I remember my very first patient in that series continued to tell me more history during what was meant to be the physical exam visit. And I began my ritual. I always begin with the pulse, then I examine the hands, then I look at the nail beds, then I slide my hand up to the epitrochlear node, and I was into my ritual. And when my ritual began, this very voluble patient began to quiet down. And I remember having a very eerie sense that the patient and I had slipped back into a primitive ritual in which I had a role and the patient had a role.
...
And I always felt that if my patient gave up the quest for the magic doctor, the magic treatment and began with me on a course towards wellness, it was because I had earned the right to tell them these things by virtue of the examination."

"

Doctors who listen to the heart every time they see a hospitalized patient don't do so because they think they will pick up a new murmur, or because they think the patient will suddenly develop a new cardiac disease.  They do so because the patient expects a doctor to do so.  When a patient sees and feels someone putting a stethoscope on their heart, from the moment they are an infant to their dying day they are trained to think "Okay, that's the doctor and I'm the patient.  They are a miracle worker, here to care for me."

By putting a stethoscope on a patient's heart and lungs, by pushing on the belly, by shining a light in the patient's eyes- doctors tap into a cultural understanding that goes back to Hippocrates.  Every examination done by a smiling pediatrician.  Every dreaded visit to a doctor with one's aging parents.  Every bad TV show, one of which hysterically depicts an orthopaedic surgeon using a stethoscope.  All of it culturally programs patients to put their trust implicitly in the person with an MD after their name and a stethoscope around their neck.  And what trust!  The patient may let a random person who they may have never seen before in their life give them dangerous medications, examine them in extremely intimate ways, and even cut them open and perform surgery.

So, how does an electronic stethoscope play into all of this?  It simply doesn't.  Doctors will not see any great advantage for using Eko over a regular old stethoscope which won't run out of batteries or require extra button presses and documentation.  One can argue that it should form a cheaper alternative to an ultrasound- but ultrasound machines are significantly more accurate, and getting cheaper every day.  Even in resource poor settings like parts of Africa, hand-held ultrasounds are significantly more accurate than stethoscopes and have been successfully used.

Now, why did I include that disclaimer and state that this device might still be a success?  Firstly, it is conceivable that I am wrong, and that computer analysis of thousands upon thousands of heart sounds recorded by Eko can make the device coupled with a computer as accurate at diagnosing heart conditions as an echocardiogram.  I don't think this is likely- for reasons stated above, listening to the heart is inherently inaccurate, and even if it could pick something up, the patient would still need an echo and other tests to characterize the lesion prior to operative or non-operative intervention.  Secondly, some might argue that patients might be able to keep such a device at home, and let cardiologists hear their heart sounds remotely as has been done by AliveCor with EKGs.  But this again runs into the same problem as above- would any cardiologist trust their ears and not get the patient to the nearest Emergency Department for an Echo?

The real reason this device might yet be a success lies in this throwaway sentence from that article:

" 'Maybe it can do it in a better way than the human ear can, and maybe it can tell us something about the human heart that we didn't really know before,' Chorboa said."

This is the only possible reason in my view that this device could be useful.  If somehow the sounds produced by the heart recorded electronically over a period of time can produce a new understanding or new way to measure and track the heart, provide information that simply could not be gathered without it, then it may be successful.  Perhaps we will find a way to determine the true volume status of someone instantly, reliably guiding fluid management in patients with multiple medical problems.  Perhaps wearing this device for a day can function as a cheaper alternative to stress tests.  I really couldn't say, since by definition any new use discovered for this device would be revolutionary.  But such a bet is a heady one to make- and in any case, America's 700,000 physicians will hardly run to buy one without such an effect being demonstrated- which may take quite some time to do.

Ultimately, I do not see Eko being successful at least in the short term.  It is yet another product of failures on the part of an engineering team to truly understand how medicine is practiced in the modern age.