Sh!t I Learned This Week 2019.03.30

Good morning, everyone!

It’s another week gone, and thanks to weather, I’ve had some reading time this week. Last week I promised the next one wouldn’t be as long, so I’ll reel it back this week. 🙂

The Definitive Treatment of Eclampsia is Child Birth… Or is it?

Quick scenario: 24 year old female, ground EMS is called for new onset seizure. You arrive and notice that the patient’s husband is holding a very young infant. What’s your differential? You do a complete assessment and notice what appears to be a recent C-Section. How about now?

The data varies slightly, but between one third and one half of all eclampsia occurs postpartum! And not just kinda postpartum; depending on the source, such as this one, postpartum eclampsia occurs up to 4-6 weeks after deliver. Here is a case study of eclampsia ocurring 8 weeks postpartum. Crazy!

Permissive Hypotension With Traumatic Brain Injury

I really enjoyed a webinar this week on the prehospital treatment of Traumatic Brain Injuries that was hosted by EMS1. (Update: A recording of the webinar can be found here.) I had a couple of takeaways, and I’ll share a few of my favorites.

I do not think that permissive hypotension is a new concept to any of us. What I didn’t know was that, besides the fact that the evidence for it is relatively weak, that all of the studies to show an improvement in mortality excluded TBI patients. All available quality evidence indicates that hypotension of any form increased poor outcomes in TBI patients. What does that mean for our practice? Consider this as well.

We all know that a systolic blood presssure less than 90 is considered hypotensive. How did we get that number? It turns out that that number came from a massive sample of adults at their primary care physician who had their blood pressure taken. The average was obtained, and then the bottom 5th percentile of those pressures was chosen to define hypotensive. That 5th percentile was 90. Seem a little arbitrary to anyone else?

This opened my mind to my treatment. Nothing pathologically significant changes once that patient’s blood pressure goes from 91 to 89; at least nothing that doesn’t happen going from 93-91. In fact, in the TBI population, the morbidity is a straight line that increases as the blood pressure drops down from about 135 SBP. That’s definitely a higher blood pressure than I would have guessed. According to the data, starting at about 135 SBP, for roughly every 10 points the blood pressure drops in a TBI, your morbidity increases about 20 percent over the previous 10 points. This even applies if the blood pressure drop was transient. There is no difference in the rate before or after 90 according to the study that should be released soon from Dr. Daniel Spaite at the University Of Arizona College Of Medicine.

Dr Spaite was not able to release any recommendations about actual treatment recommendations until the study is publicly released, but he should be releasing the results soon. I won’t be making any specific practice changes until that information is released, but I know I will be much more conscious of any blood pressure change I might cause in a TBI, even if the patient does not fall under the typical “hypotensive” definition. I also will be much more conscious of the issue of allowing permissive hypotension in the TBI population. (The source for the above information will be in the webinar recording that I’ll share as soon as I get it.)

This week I feel like I broke a couple of foundational beliefs that I’ve held onto all the way back to the stone ages of EMT-B school. I always assumed that there was something magic about the number 90; permissive hypotension applied to every trauma patient; and child birth fixed eclampsia. Hopefully a few of these were new for you too!