[IMPROVEDX] Diagnostic Error in Medicine Journal Club

robert bell rmsbell200 at YAHOO.COM
Mon Mar 7 20:03:45 UTC 2016


Dear Gervais,

I would like to make a few polite comments on the e-mail below.

Dear Gervais,

Firstly, the bare arm versus sleeved arm study is deeply flawed by the design and one can also make comments on other aspects of the study.  

Machine precision is oft-quoted, but compared with what? (Usually additional machine measurements whose wider variation fails to detect a difference). One would ask what is a sleeve, what thickness, what fabric, loose or tight, etc.? Does it include a heavy wool shirt. 

Random zero mercury manometers could have been used throughout the study; these are known to be much more precise than automatic machines, because (non-deaf) physicians' ears are much more sensitive to blood flow turbulence than detectable pressure variations by machine.  But even then the study design would have had a second measurement risks bias by knowing the first estimate.  Since all the first estimates were bare arm, there is a large false negative bias on the second measurement being any different, regardless of whether bare or sleeved. 

And some comments on auscultation with a shirt, bra, or blouse. Most physicians no longer understand auscultation of the chest, let alone do it properly, due to time pressures, lack of knowledge and perhaps even laziness. Many physicians have listened to my chest through a regular shirt T-shirt, or both. I believe that few understand that a stethoscope has a cone and a diaphragm for good reasons. The physicians who press the cone tightly against the skin convert the skin into a diaphragm, and thus miss low frequency sounds even on a bare chest. Chest movement of a shirt across both a cone and a diaphragm causes artefactual crepitations, usually quite loud, that will mask sounds of lower volume. Loud aortic murmurs radiating up the carotids can still be heard (by applying stethoscope over carotids which are usually unclothed (but this is still another nearly lost art). Would you notice a pes cavus under a shirt that displaced the apex beat laterally giving a false impression of an enlarged heart?  You might as well not bother, and just send everybody for an ultrasound, and help the radio-imaging people’s salaries!  

Even in this dire age, I still believe that in some medical schools students would still be failed in their examinations for not taking off the patient's shirt. 

I do not believe that I am making assumptions. My plea is for understanding the evidence base and having a good reason to depart from good medical/clinical practice. I would add that less tangible factors such as previously undetected breast lumps or peau d'orange of the breast or chest wall, etc., etc, etc., are negligently missed  by failing to examine the patient properly. And that requires removing clothing.  

Unfortunately, one can ask is the the stethoscope just a badge of office? As you have heard me say before the stethoscope is probably the most inaccurate support instruments that we as physicians/HCPs frequently use. I would guess that the stethoscope would have a fairly significant error rate in different groups of HCPs depending mainly on the make of the stethoscope, the use of the bell/diaphragm, hearing acuity, and particularly training and experience of the user. Which brings up the idea that the IOM could probably help medicine very significantly by doing a definitive study to prove or disprove this hypothesis.

Is there enough evidence to relegate the stethoscope to the trash can? Would we then overall dramatically improve our diagnostic accuracy?

Finally I believe that it may be foolhardy to focus on just diagnosis, ignoring or partially ignoring, all the support diagnostic factors that have significant error rates. These need working on.

Thanks Gervais for stimulating comments.

Rob Bell, MD
> On Mar 4, 2016, at 11:20 PM, Wansaicheong Gervais Khin-Lin (TTSH) <gervais_wansaicheong at TTSH.COM.SG> wrote:
> 
> Dear Robert,
>  
> Re: blood taking with a sleeved arm
>  
> The answer is 0.76 mmHg for systolic and -0.31 mmHg for diastolic (See reference below).
> Stop making assumptions – the first thing that happens in cognitive errors.
> And don’t assume that the other questions raised aren’t valid – I just haven’t looked up the answers.
> :-}
> 
> Gervais
>  
> A comparison of blood pressure measurement over a sleeved arm versus a bare arm
> Grace Ma, MD, Norman Sabin, MD, and Martin Dawes, MBBS MD
> CMAJ. 2008 Feb 26; 178(5): 585–589.
> doi:  10.1503/cmaj.070975
> PMCID: PMC2244664
> http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2244664/ <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2244664/>
>  
>  
>  
> From: Robert Bell [mailto:0000000296e45ec4-dmarc-request at LIST.IMPROVEDIAGNOSIS.ORG <mailto:0000000296e45ec4-dmarc-request at LIST.IMPROVEDIAGNOSIS.ORG>] 
> Sent: Sunday, 28 February 2016 1:12 PM
> To: IMPROVEDX at LIST.IMPROVEDIAGNOSIS.ORG
> Subject: [IMPROVEDX] Fwd: [IMPROVEDX] Diagnostic Error in Medicine Journal Club
>  
> 
> 
> Sent from my iPad
> 
> Begin forwarded message:
> 
> From: robert bell <rmsbell200 at yahoo.com <mailto:rmsbell200 at yahoo.com>>
> Date: February 27, 2016 4:57:56 PM MST
> To: Art Papier <apapier at VISUALDX.COM <mailto:apapier at VISUALDX.COM>>
> Subject: Re: [IMPROVEDX] Diagnostic Error in Medicine Journal Club
> 
> Art, Nice response.
>  
> I think there is so much we do not know - perhaps where we should start.
>  
> "Diagnostic things at our disposal" (or the diagnostic infrastructure - to get from A to B we need a few bridges, tunnels, and maybe ferries). Stethoscope, fingers, tongue blade, communication (language barriers), variation in presentation, completeness of history and physical, etc. etc. all become part of the standard work up. - Labs, EKG, or imaging would add to the error load). All of these have differing errors in different hands. Do we know what these are? Should we know?
>  
> We do not know the error rate on all of them, do we even know if one is more important than the other.  Do we know the percentage of patients seen by differing physicians who are just history and physical patients (no labs, EKG, or imaging)? 
>  
> I would have thought that the stethoscope in different hands had the greatest error - but could be wrong. 
>  
> I would also think that most/many physicians had high frequency hearing impairment (particularly the young with loud music exposure). I am not sure what effect that has on diagnosis but presumably adds to the error rate - should we know? If hearing loss is significant should those HCPs use stethoscopes?!
>  
> We do not know what is the overall level of handicapped physicians (with impaired physicians - drugs, alcohol, emotional there are probably figures from the State Medical Councils) - the handicap could be in many different areas. Pilots have pretty strict physical exams. Should Physicians? Should we know?
>  
> Speed is a big problem and I suspect related to the Burn Out Rate. And it must also impact accurate diagnoses. 
>  
> Here is the link to the AMA report by specialty. http://www.ama-assn.org/ama/ama-wire/post/specialties-highest-burnout-rates <http://www.ama-assn.org/ama/ama-wire/post/specialties-highest-burnout-rates>
>  
> Thanks for your comments on Simulation, CDS, EHR, and I will throw in telemedicine - all so valuable. How can we to get some of these thoughts researched and if working introduced so we can start making changes and saving a few lives?
>  
> But there is so much error in the history and physical with and without labs or imaging that it is foolhardy to focus on diagnostic errors alone. The infrastructure really needs repairing.
>  
> Whenever I see a PCP or Specialist, Nurse Practitioner, or Physician’s assistant, approximately 80% listen to my chest and heart through my shirt. What is that doing to accuracy? Do we know? Similarly a BP measurement through clothing (are there studies there that tell us the error in mm of Hg?). How accurate is taking the BP in a non-approved way?
>  
> Let’s start with the basics. Which brings up the thought, WHAT IS OUR MISSION AND WHAT ARE OUR SPECIFIC GOALS TO GET THERE?
>  
> Thanks Art,
>  
> Rob
>  
>  
> (removed for brevity)
>  
> 
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Robert M. Bell, M.D., Ph.C.
P.O. Box 3668
West Sedona, AZ  86340-3668
USA
Tel: Fax: 928 203-4517









Moderator: David Meyers, Board Member, Society to Improve Diagnosis in Medicine


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