Saturday, August 13, 2016

The Enemy of Good is Better: Maximizing versus Satisficing in Clinical Medicine

Recently I was called to admit a little old lady with a digoxin overdose who had symptomatic bradycardia.  She was in her 70s, had Alzheimer's disease (AD) and a medication list that would not print on one page.  I immediately thought, what benefit does digoxin have that justifies even the occasional admission for toxicity?  That's a good question in its own right, but consider a partial list of her other medications:

  1. pantoprazole
  2. lisinopril
  3. gabapentin
  4. raloxifene
  5. estradiol
  6. donepezil
  7. labetolol
  8. furosemide
  9. glipizide
  10. fenofibrate
  11. memantine
  12. sitagliptin
  13. spironolactone
  14. amlodipine
  15. alprazolam
  16. aspirin
One certainly must wonder what goals her providers are trying to achieve with these and indubitably some other medications which aren't listed.  Her husband was frustrated when I told him that many of the medications she is taking are not really doing her any good.  "They why do they have her taking them?" was a question I could not answer, because it doesn't make sense to me either.  Exasperated, he offered a great analogy:  "Suppose you hire me as a contractor to build you a home, and I tell you that you need to build a 14 foot high retaining wall in the back yard, two feet thick, reinforced with rebar and containing 20 yards of concrete.  Would that be responsible unless it were absolutely necessary?  What kind of contractor would recommend something you didn't really need?"

"A physician contractor," came the ready answer in both of our minds, and we simultaneously nodded in understanding.

Thursday, August 11, 2016

Medical Decision Making as a "Patient": Pregnancy Leads to A Trip Down The Rabbit Hole - A Personal Story

My wife is pregnant.  Wanting to be a supportive spouse, I attended the first prenatal visit to see one member of her team of midwives.  (Being a "minimalist" I was, like my wife, fond of the idea of not unnecessarily "medicalizing" the [usually] natural act of labor and birth.)  I realized during that first visit that understanding the intricacies of medical decision making can be a double-edged sword when dealing with practitioners, especially outside of one's specialty.  If ignorance is bliss, 'tis folly to be wise, it is said.  I've come to wonder which is better for you when you get entangled in US healthcare, wisdom or bliss.

During the first visit, we were offered, with an air of agnosticism, a referral for genetic counseling +/- non-invasive prenatal testing (NIPT).  "How accurate is it," I naturally inquired, trying to avoid technical terms such as sensitivity and specificity.  "Something like 99%" came the reply.  So we were given the referral.  But I quickly realized that this was a classic problem of base rates.  The likelihood of a chromosomal abnormality is so low given my wife's age, that even extremely high sensitivities and specificities are inadequate to guide our decision - that is, the test is rendered practically useless because of the low base rates in our case.  And this despite the fact that the sensitivities and specificities of prenatal blood testing are inflated by the way they were derived.  But think of the decision we would have faced had we blindly proceeded with testing without this consideration - given the low base rate, the posterior probability of a chromosomal abnormality such as Down's Syndrome given a "positive" test result would be around 33%.  How would we act on this information?  Is that threshold high enough that we would consider an elective abortion (if we were morally disposed towards that as an option)?  Or would we ignore the information and proceed to term?  And if we were not ethically accepting of elective abortion as a possibility, what other remedy would we have that would justify the information from the testing?  Why would we talk about getting prenatal genetic testing before talking about the choices we may have to face after we receive the results?  Why would not a discussion of remedies, specifically abortion, precede consideration of the testing?  How many couples dive into the rabbit hole only to wonder how they got there and how they can get out?  In this case, we decided that ignorance was indeed bliss, and deferred NIPT.

At that same visit, blood was ordered to be drawn.  I had difficulty understanding why you would need to draw blood from a perfectly healthy woman at 12 weeks gestation.  Blood types and anemia and all that I guessed.  But I was particularly caught by the thyroid testing.  Why are we screening an asymptomatic woman for thyroid disease?  Is that justified by the prior probabilities?  It takes only a google search to learn that ACOG (the American College of Obstetrics and Gynecology) and an endocrine society do not recommend universal testing.  But my questioning why we were doing this was off-putting and frankly unanswerable for the midwife - she was just following the usual routine, whatever her supervisors and mentors had told her to do, without understanding....well without understanding any of this Bayesian mumbo jumbo that I was hinting at.  Alas, thyroid testing, like NIPT, was deferred.  But not for long.

Tuesday, June 14, 2016

The Lost Art of Landmarking: Right Internal Jugular Insertion Video

I have long wanted to post a video of central line insertion using the traditional landmarks method, and recently I was afforded the perfect opportunity.  The patient needed a dialysis catheter.  He had had one inserted a few months ago and it had been a disaster for him.  First, the inserting physician mistakenly installed a Cordis Introducer instead of a dialysis catheter, using ultrasound guidance and causing a good deal of pain by transecting the belly of the sternocleidomastoid (SCM) muscle, then it was rewired to a dialysis catheter that would not flow, then, finally, a working catheter was installed in a new site.  I assured the patient that this go at it would be much easier and he was very interested in having the experience recorded so he could later see it, and others could learn from it.

I previously observed that in the current training atmosphere, trainees are paying no attention to anatomical landmarks, rather they are just poking wherever they see the vein on the ultrasound image, traversing whatever structures lie between the surface and the target, without any care whatever.  It is my belief that the SCM muscle should never be split/transected with a dilator or line unless absolutely necessary.  Thus even if ultrasound is used, the landmarks ought to be identified and respected.

Several points in the video need further explication here.  (Beyond the facts that my nose did not fit under the mask, I did not wear eye protection, and that I failed to lay out the components of the tray beforehand.)

  • The importance of properly and confidently identifying the bellies/heads of the SCM cannot be overemphasized.  I will at some point do another video to go through that process specifically in detail.
  • I always keep 0.5-1.0 cc of liquid (lidocaine or flush) in the syringe during needle passes.  In my experience, it minimizes clotting in the needle and the risk of passing through the vessel without flash due to clot.
  • In contrast to what is suggested in the NEJM video for RIJ CVC insertion, I do not hold the needle at 45 degrees to the floor plane when going after the IJ.  Doing this makes you have to insert the needle much deeper, increasing the risk of pneumothorax.  I prefer an angle of 60-90 degrees.
  • In this patient, the IJ was deeper than usual and than I expected, thus I did not hit it with the "seeker" needle.
  • When the fingers of my left hand are on the neck, I am not palpating the carotid pulse.  I could care less about the carotid.  I am feeling that medial belly of the SCM as a landmark and ever so gently pushing it to the left to increase exposure of the IJ underneath of it.
  • When entering the skin with the large bore needle, I poke to and fro rapidly to keep it from "breaking through" the skin and plunging too deep.
  • Notice that each centimeter or so that I enter with the large bore needle, I pause and pull back a bit to see if I get flash in case the vessel is compressed on the forward pass.  In the video, I get flash on the second or third pull back.
  • After I get flash, I then lay the needle back to 45 degrees to facilitate guidewire passage
  • This patient's skin and subcutaneous tissue was tougher than I expected and I did not make a generous enough stab incision into the subcutaneous tissues to make a tract for the dilator.  Usually I use a regular 7.0 French triple lumen CVC kit dilator first, then the smaller of the two dilators that come with the larger 12 French dialysis catheter.  This is a new all-inclusive kit that we began using which contains only the large dilators.
  • The bleep is to protect privacy
Stay tuned for the subclavian vein CVC insertion video next!

[Formal written consent was obtained from this patient to make this video and to publish it for educational purposes.]

Special thanks to Clayton MS4 for filming this and helping with editing.  Other medical students are encouraged to participate in future web and social media initiatives.  I have several in mind.

Friday, June 3, 2016

Doctorin' with Double Effect Part II: The Devil is in the Details

In a prior post, Doctorin' with Double Effect, (a double entendre with Doctrine of Double Effect) I attempted to tease out ethical issues related to the withdrawal of life support and specifically the provision of oxygen in dying patients.  The simplest case is that of a moribund patient who is completely dependent upon life support measures such as mechanical ventilation and vasopressors.  In such a patient, withdrawal of these measures often allows a quick death to ensue.  Provision of oxygen in such a patient will not avert death, but will prolong it, so I think that while oxygen is often reflexly applied to such patients, I can say with some confidence that it should not be.  While it is mostly benign, it generally does not provide comfort and it prolongs the dying process so it is on the net futile or harmful.  I struggle to reconcile my strong pragmatic intuition about this with ethical principles such as the DDE, although I think it is consistent with the notion that I can take away something that restores a natural state to abrogate its associated discomforts or in deference to patient autonomy and a wish to have a "natural death."
But there is a very large grey area.  What about patients in whom death is not imminent?  Consider a patient who has been on the ventilator for a week with dementia and aspiration pneumonia, and who has developed weakness.  He is alert, but not oriented.  When he is extubated, it is expected that he will develop retained secretions, atelectasis, and over several days, obtundation and oxygenation and ventilation failure.  But over several days.  Should oxygen be administered in the hope that he will rally?  Does its deprivation deprive him of a chance of survival that is disproportionate to the removal of the endotracheal tube and the mechanical ventilator in terms of net costs and benefits?

Or, consider the patient who is demented and is admitted with pneumonia from aspiration and who is DNR/DNI and is given supplemental oxygen.  Does escalation of oxygen therapy to a non-rebreather mask from nasal cannula fly in the face of his DNR order?  Does the administration of peripheral vasopressors for hypotension have the same result?  Does DNR/DNI mean Do Not Respond/Do Not Intervene?

Friday, May 13, 2016

Don't Judge a Brain By It's Scan: The Importance of Actionable Information in Medical Decisions

A common and vexing problem in ICUs everywhere is posed by the patient with diffuse encephalopathy or coma - patients who are colloquially said to be "out to lunch" or "the lights are on, but nobody's home."  The underlying cause is usually a toxic, anoxic, or metabolic malady and the only available treatment is to remove the underlying insult (toxin, hypoxia, or metabolic derangement, e.g, uremia) and wait patiently to see if the neuronal injury improves or resolves.  That is perhaps the hardest part - waiting patiently, with all the attendant uncertainty and resulting anxiety, for days, or even weeks.  This, despite my knowledge that the vast majority of these patients, save for those with severe anoxic brain injury (ABI) will mostly or completely recover with supportive care and "tincture of time."  It is very difficult for me, as a physician, to watch, mostly knowing that the patient has been "out to lunch" for the past 72 or 96 hours because of drug effects, which is very common.  "Shouldn't the drugs be cleared by now?", I keep asking myself.  "Maybe I'm missing something," comes the id's reply.  This anxious uncertainty serves as an impetus for action - but what action is there to take, and is it helpful on balance?

The urge usually is to get a variety of neuroimaging tests, CT (the "donut of truth"), MRI, MRA, and probably an EEG.  But I resist this urge mightily.  These tests rarely yield actionable information - that is, data that I can act upon to change the course of care, as an alternative to waiting.  Say for example, as is often the case, the CT scan and the MRI scan are normal.  How has this helped me?  I still have a comatose patient, and I'm still stuck waiting.  (Also, without meticulous care in explaining the test's purpose and results to her family, confusion ensues.  "If the MRI is normal, why is she in a coma?" is a commonly uttered frustration.

Alternatively, the MRI can look horrible and the patient can still do very well.  I recall a case about a decade ago where we sent a patient with hepatic/toxic/metabolic/anoxic encephalopathy to "the magnet" (MRI scanner) and the neuroradiologist soon after called:  "Is this patient still alive?" he demanded.  Yes, indeed she was.  "Well she won't live long, her whole cortex is necrotic! [rotten]," he forcefully propounded.  Two days later the patient awakened.  I do not believe the radiologist's read of the MRI was in error, only that he erred in confidently inferring that function follows form.  "Don't judge a brain by it's scan" might be a useful heuristic here.  Telling this anecdote to patients' families led me to stumble upon a communication pearl:  My not getting the scan is in essence giving the patient the benefit of the doubt - because I don't want to find something that looks bad and ruins my optimism.  This is generally a very positively received explanation for families who may themselves be demanding scans, action, do something, Doc!

There are indeed cases in which radiological imaging does reveal important and undeniable information, such as stroke, hemorrhage, herniation, and swelling.  I do not impugn all scans, many times they are very useful.  I only wish to cast skeptical doubt on that large fraction of scans which are done as a pat response to non-specific encephalopathy where they are unlikely to yield actionable information.

Beyond the costs, radiation, and risks of transportation associated with the routine use of these scans, which are often not counterbalanced by the yield of actionable information, there is a psychosocial cost - in my observation, these scans increase families' anxiety.  Firstly, when you say you're going to order an MRI, false hope that we can learn what cannot yet be learned (until enough time has passed for the patient to awaken) is engendered.  The family inevitably wants to know when the MRI will be done.  The nurse says 4 PM, there are invariable delays, it gets done at 10 PM.  Anxiety pervades all of those hours.  When will it be read?  Nobody knows, but we offer "in an hour" as a guess.  More anxiety, until 1AM when the report becomes available - but it's inscrutible.  It talks of diffusion weighted this and that, and the neurologist is not available to put it into context.  Anxiety mounts.  In the morning, the neurologist attempts to explain all these little areas of this and that, or a normal scan or whatever.  But none of it tells the patient's family what they want to know, namely "Will my mom awaken?  When?"  Those questions remain unanswerable, but the family has been put on a psychic roller coaster for the past 24 hours thinking the MRI will answer them.  When it is finally done, the reason they can't divine the meaning of the scan is because there is no meaning of the scan - it is devoid of actionable information and should not have been ordered in the first place.

Monday, February 22, 2016

Procedure Meat: How Procedural Lust Imperils Patients

I'll start with a macabre anecdote of crassness, to get everyone's attention.  It is apropos because procedural lust has crass and macabre consequences.

It was about 17 years ago, while I was in training, that an attending accepted a moribund woman from a faraway place in the hinterlands.  She had multiple hepatitides and uncontrolled bleeding from esophageal varices.  A collective groan among the housestaff met notification of the incoming transfer which would keep everybody up all night with the inevitable death forestalled only briefly, and in a streak of his usual candor, the attending admitted that he accepted her not because he thought there was anything that could be done to help or save her, but because she would serve as good "procedure meat for the interns."

There are a lot of problems with that entire episode as I reflect upon it, and I won't dissect them all here.  I've been thinking about procedure meat because I so often see physicians feasting on it, to the peril of the patients.  Ideally, each and every procedure that is done ought to be done because it is in the patient's best interest to have it done.  All too often, ulterior motives and unstated goals creep into decision frameworks and lead to unnecessary procedures and therapeutic misadventures.  To combat this problem, we need to start nudging physicians to consider and patients to ask directly, "Is this procedure the best thing for me?  Are there alternatives?  Do the expected benefits outweigh the costs and risks?  Where will I be in six days, six weeks, six months, and six years as a result of the proposed procedure?  Where will I be at those times without it?"