Category Archives: Philosophy

Why People Don’t Change Their Minds Despite The Data

Has this happened to you?

Your (emergency physician / neurosurgeon / orthopaedic surgeon) colleague wants to (get rib detail xrays / administer steroids / wait a few days before doing a femur ORIF). You question it based on your interpretation of the literature. You even provide a stack of papers to them to prove your point. Do they buy it? Even in the presence of randomized, double-blinded, placebo-controlled studies with thousands of patients (good luck finding those)?

The answer is generally NO! Why not? It’s science. It’s objective data. WTF?

Sociologists and psychologists have shown that there is a concept that they call the Backfire Effect. Essentially, once you come to believe something, you do your best to protect it from harm. You become more skeptical of facts that refute your beliefs, and less skeptical of the items that support them. Having one’s beliefs challenged, even with objective and authoritative data, causes us to hold them even more deeply. There are plenty of examples of this in everyday life. The absence of weapons of mass destruction in Iraq. The number of shooters in the JFK assassination. President Obama’s citizenship.

Bottom line: It’s human nature to try to pick apart a scientific article that challenges your biases, looking for every possible fault. It’s the Backfire Effect. Be aware of this built in flaw (protective mechanism?) in our psyche. And always ask yourself, “what if?” Look at the issue through the eyes of someone not familiar with the concepts. If someone challenges your beliefs, welcome it! Be skeptical of both them AND yourself. You might just learn something new!

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Life Threatening Bleeding In The Anticoagulated Patient – Part 3

Over the last two posts, I’ve explored some of the current definitions of “life-threatening bleeding” and shared my own take on a simplified yet more universal definition. So how can we put this into practice?

In the trauma world, we typically need to use this definition when dealing with patients who are taking anticoagulants. When a patient on this class of drug arrives at your center after trauma, they must be evaluated promptly. This is frequently in the form of a trauma activation, which provides rapid access to labs and imaging. If the patient does not meet activation criteria, some type of expedited response (limited activation or rapid evaluation by emergency physician) is required. The most important decision that must be made is, “does this patient need to have their anticoagulant reversed?”

This decision depends on the answers to the two criteria I laid out in the last post. Is either of these present?

  1. (Physiologic) Bleeding that causes hemodynamic compromise (hemorrhagic shock) or changes in vital signs indicating progression toward it (increasing pulse rate, decreasing blood pressure).
  2. (Anatomic) Bleeding into a body region or tissues that has a high likelihood of causing death, disability, or the need for operative intervention.

The first one is easy. Actual or developing hypovolemic shock should be obvious to any clinician managing the patient.

The second one is not necessarily as apparent. Although one may think that any intracranial blood may be life-threatening, sometimes it is not. What about a little subarachnoid hemorrhage? Or a tiny subdural in an area that typically does not progress?

So how to we determine if definition 2 is met? Phone a friend. Call an expert. There are so many potential areas for this type of bleeding to occur, a single emergency physician or other clinician may not be able to accurately make this judgment. So call your friendly, neighborhood neurosurgeon (head), or surgeon (abdomen, soft tissues), GI specialist (UGI bleed), or obstetrician (baby stuff). If they agree that it is life-threatening, the reverse the anticoagulant.

This level of oversight is important, because the reversal agents are not totally benign, or cheap. They have known complications, and one rare but important one is death. So make sure that their use is justified.

Final tips: Once you have determined that reversal is required, use the fastest agent(s) available. For warfarin, this means prothrombin complex concentrate (PCC) and not plasma. Typically, plasma reversal requires at least 4 units, and this takes hours. PCC takes 30 minutes or less. 

Document your judgment well, and your conversations with specialists who are helping you with definition #2. This is critical, because there have to be checks and balances for use of your rapid reversal protocols. There must be a post hoc analysis of each and every reversal, just like there should be for use of your massive transfusion protocol. A group of knowledgeable clinicians must review the clinical information that was available at the time of presentation, and render their agreement or disagreement to provide a good feedback loop and ensure proper usage of these products.

 

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What Is: Life Threatening Bleeding In The Anticoagulated Patient – Part 2

In my last post, I showed you some of the current definitions of “life-threatening” bleeding used in patients who are anticoagulated, as well as some for lesser degrees of bleeding. Confusing, right? How are we to ever know what is truly life-threatening so we can justify intervention/reversal with potent and/or expensive drugs and blood products?

It’s time for a more universal definition. The most important thing to recognize up front is that it is absolutely impossible to provide a comprehensive set of definitions that take every possible scenario into account. The list would be confusingly long. We really only need a few rules that are a bit more generalized. But then, how do we keep providers from just doing what they want, and coming up with some subjective or anecdotal justification? Bear with me for a day or two.

Today, I’ll lay out my two “universal definitions” of significant bleeding in an anticoagulated patient. Note that I didn’t say “life-threatening” bleeding. There is also such a thing as “limb-threatening” or “tissue-threatening” bleeding, and yet other ways to be harmed from uncontrolled bleeding due to anticoagulants.

If you look through all the various criteria that I included in the last post, you can see that they generally fall into two categories: physiologic and anatomic. The key is to reach a balance of being specific enough without being overly so. This still allows for some degree of clinician judgment. But as you will see in my next post, there also has to be some type of scrutiny and review of that judgment.

So here is what I propose. Bleeding is considered significant and/or life-threatening if either of these are true:

  1. (Physiologic) Bleeding that causes hemodynamic compromise (hemorrhagic shock) or changes in vital signs indicating progression toward it (increasing pulse rate, decreasing blood pressure).

  2. (Anatomic) Bleeding into a body region or tissues that has a high likelihood of causing death, disability, or the need for operative intervention.

In my next post, I’ll show you how to operationalize these definitions into a workable process for making decisions about reversing anticoagulation.

 

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What Is: Life Threatening Bleeding In The Anticoagulated Patient – Part 1

We are moving into a world where more and more people are taking anticoagulants. And as the number of possible anticoagulant drugs increases, the prospect of reversing them becomes more complicated. Just as the price of those medications continues to climb, so does the price of the agents used to reverse them.

The decision to reverse an anticoagulant, the speed of reversal, and choice of reversal agent all depend on an assessment of the severity of bleeding. Some reversal drugs such as prothrombin complex concentrate (PCC) act almost immediately but are expensive. Others take time, but are cheaper such as plasma and vitamin K.

Unfortunately, trying to come to a consensus on what constitutes life-threatening bleeding is very difficult. Over the years, numerous studies have been done, with almost as many definitions of bleeding. As you know, I am generally against reinventing the wheel. Borrowing someone else’s excellent work saves a lot of time and anguish.

But when it comes to defining dangerous bleeding, we are faced with so many definitions, it just begs for a “unifying theory.” I’ll show you some of the more commonly used definitions below. At the very bottom, I’ve included a link to a very comprehensive list of definitions that have been used.

First, there’s TIMI (Thrombolysis in Myocardial Infarction trial) and GUSTO (Global Use of Strategies to Open Occluded Arteries trial). (Please remember how much I dislike cute acronyms.)

The following consolidated definition was published in the Journal of Thrombosis and Haemostsis way back in 2005:

If you want to look at a more comprehensive list of a lot of definitions, download the document from the link below.

So how do we make sense of all this? As trauma professionals and clinicians on the front line of anticoagulant reversal, we need a simple definition. I’ve recently looked over as many definitions as I could lay my hands on. 

In my next post, I’ll propose a simplified set of definitions. And I’ll be very interested in your input and comments. They will ultimately end up as a definition that we will use at my own trauma center. And maybe yours.

Related post:

Reference:

  • Definition of major bleeding in clinical investigations of antihemostatic medicinal products in non-surgical patients. Journal of Thrombosis and Haemostasis, 3: 692–694, 2005.
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Serial Lab Testing: Worthwhile or Worthless?: Final Answer

In my last two posts, I detailed the serum sodium measurements in a hypothetical patient two ways. The first was a listing of daily values, and the second provided values obtained every six hours or so. It also showed the sodium supplementation that was ordered based on those values. (I’ve included the table at the bottom of this post)

What did you think? Did the extra determinations help you decide what, if any, treatment was needed? Did the therapies ordered help?

Here are my thoughts:

  • Overall, there was not a huge or rapid decline in sodium values. Given the initial values, I would not have started a saline infusion on day 1, just watched a few daily values and the patients physical exam. The infusion only provided 3gm of salt per day, and the serum Na remained fairly stable for the first 3 days.
  • There was a significant amount of intra-day variation seen on the six hour table. You need to know the normal “within-person ” variation for any lab test you order. If two assays on specimens drawn at the same time can vary by 5%, you must factor this in to your decision making. If the value is 3% lower than the previous draw, the difference could represent normal variation. Obtaining more frequent assays exacerbates the amount of variation you see and my be confusing.
  • From day 5 to 6, the sodium appeared to be rising without any salt supplementation! But then a higher dose was given, and one of the intra-day values dropped to 124. What’s up with that? More variation?!
  • Is the morbidity of frequent blood draws worth it if there is no clinical change in the patient’s exam? What morbidity, you ask? Sleep disturbances, with all the cascading problems like delirium, sundowning, administration of additional meds to compensate, and on and on. Unnecessary medication or interventions. Plus it does not promote patient or family satisfaction at all.

Bottom line: Unless your patient has a clinical problem that may deteriorate rapidly, serial lab determinations are probably not of much value. The example patient was many days out from a TBI with some extra-axial blood. So yes, he could develop hyponatremia, but it would have probably surfaced earlier. Know your within-person  variability, which for sodium is roughly +2 meq. Is your new value within that limit? Then it is statistically the same as the first value unless you see a trend over several measurements. And as always, if you note a marked change in just one value, repeat it immediately before beginning any more drastic interventions.

Reference: Biological variation of laboratory analytes based on the 1999-2002 national health and nutrition examination survey. Natl Health Statistic Reports 21:March 1, 2010.

Day/Time Na Treatment NaCl per day
Day 1 18:30 131
Day 1 22:54 132 0.9% NS @ 125/hr 3G
Day 2 05:59 133 continues 3G
Day 2 12:19 129 continues
Day 2 17:50 129 continues
Day 3 07:18 127 continues
Day 3 12:09 127 continues
Day 3 17:58 126 continues
Day 3 23:53 126 continues
Day 4 07:45 125 continues
Day 4 11:38 122 2% NS @ 25/hr 6G
Day 4 15:25 125 continues
Day 4 19:31 125 continues
Day 5 00:06 122 continues 6G
Day 5 04:04 126 continues
Day 5 08:01 122 continues
Day 5 11:50 132 stop
Day 5 16:14 126
Day 5 19:26 127
Day 6 00:20 129 9.2G
Day 6 04:42 127 2% NS @ 40/hr
Day 6 08:30 124 continues
Day 6 12:29 127 stop
Day 6 16:16 127 Salt tabs 2G tid
Day 6 20:28 132 continues
Day 7 05:22 134 Salt tabs 2G qid 8G
Day 7 12:33 135 continues
Day 8 07:02 131 stop None
Day 8 13:33 136
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