Category Archives: Philosophy

Guidelines vs Protocols / Evidence-Based vs Evidence Informed

In my last two posts, I reviewed the importance of having practice guidelines at your trauma center and gave some pointers on how to develop them. Today I’ll give you my take on the nomenclature and the evidence they are based on.

There are lots of names given to what we have come to know as clinical practice guidelines. You’ve heard many of them. Guidelines. Pathways. Protocols. What’s the difference?

Unfortunately, there are no real and solid definitions of these terms when used for clinical care. So here is my take on them:

  • Guideline. Guidelines are general principles that guide management. These are best illustrated by the practice guidelines published annually by the Eastern Association for the Surgery of Trauma (EAST). Each EAST guideline tackles a specific clinical problem, like DVT or blunt cardiac injury. It presents a series of clinical questions regarding the topic, such as “which is better, unfractionated heparin or low molecular weight heparin.” The pertinent literature is reviewed and its overall quality is judged. Then the questions are answered and the confidence in that answer is given, based on the strength of the research (strongly recommended vs recommended vs conditionally recommended, etc.). So in reading the guideline you may see that the use of low molecular weight heparin is recommended over unfractionated heparin in certain circumstances.
  • Protocol. A protocol is a description of very specific behaviors that are followed in certain situations. The behaviors can be described either in a list format (such as that followed in some type of formal ceremony) or in a flow diagram which is best used in clinical care.
  • Pathway. In my mind, this falls somewhere between the two extremes of guideline and protocol. It is more specific than a guideline, but less so than a protocol.

In clinical care, specifics are important. Without specificity, there is still much opportunity for variation in care, which defeats the purpose. The EAST guideline described above paints some broad strokes about clinical care, but there are huge gaps between the questions answered that need answers to provide actual patient care.

So although we (and I) tend to call these documents clinical practice guidelines, they are really clinical care protocols. They should be written in such a way that care can be provided in an “if this, then that” manner. If any kind of hedging language is used, like the word “consider”, the document is only a guideline. And this fact becomes extremely important when your trauma PI program tries to monitor for compliance. It is immediately obvious when someone deviates from the protocol, while a savvy clinician can always claim that they “considered” the desired course of action before they chose their own way using a guideline.

Now, what about evidence-based guidelines? Isn’t that what we all strive for? First of all, they’re not guidelines, remember. They are protocols. And second, there is no area of medicine where the research is so detailed that you know what to do down to specific blood draw times, vital sign monitoring, or operative techniques. There is still plenty of room for debate even in something as simple as chest tube removal. Water seal or not? How long until you get a followup x-ray? The possibilities never end.

So it’s basically impossible to develop anything that is completely evidence-based. We always have to take the best evidence and supplement it with clinical experience and judgement. The latter is what we use to fill in all the blanks in guidelines. I’ve seen too many trauma centers delay writing up their protocols because they are waiting for a better paper to be published on this or that. Good luck! It’s not coming any time soon!

Bottom line: Hopefully, I’ve convinced you that we’ve got the nomenclature all wrong. What we really want are evidence-informed protocols, not evidence-based guidelines!

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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.

In general, think twice before ordering serial lab tests. Can the result actually make a significant move during that period of time? Is the margin of error for the test greater than that variability? Are you truly worried about a number that would have a real clinical impact? Always ask yourself these questions before ordering an expensive and uncomfortable series of tests!

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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Serial Lab Testing: Worthwhile or Worthless? Part 2

Yesterday, I posted a series of sodium levels that were drawn daily. There was no change in clinical status as the levels varied from 131 to 125 and back up.

Now let me give you a bit more information. The patient was actually getting serial checks every 6 hours (or more)! Here’s the updated chart:

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

Confused? Me, too! This poor person had 30 blood draws in 8 days, with 6 per day for two of those days. Carefully look at the amount of salt given in each 24 hour period, and look at the sodium levels for that day.

See the variability, even when getting high doses of sodium chloride? What does this tell you? Was the salt administration helpful? Was seeing the lab value every 4-6 hours valuable?

Tell me what you think. Leave comments or tweet your opinions. Next, I’ll discuss the known variability of the serum sodium assay, and give you my opinion on the value of serial testing.

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Serial Lab Testing: Worthwhile or Worthless?

We’ve all done it at some point. Serial hemoglobin. Serial sodium. Serial serum porcelain levels. What does serial mean to you? And what does it tell us about or patient?

Today and tomorrow, I’d like to present an example from real life. For today, have a look at the daily sodium tests done for a patient with a head injury. The concern was for cerebral salt wasting, which is probably grounds for its own blog post.

So have a look at this series of sodium determinations. It represents serial values based on daily testing.

Day/time Na
Day 1 18:30 131
Day 2 05:59 133
Day 3 07:18 127
Day 4 07:45 125
Day 5 04:04 126
Day 6 04:42 127
Day 7 05:22 134

At what point, if any, would you be concerned with significant hyponatremia, and begin some type of supplementation?

Tomorrow, I’ll provide a little more info on levels and treatment

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