The only thing I would add to this is a more physiological way to assess the IVC, which I’ve blogged about here. Sadly, I’ve heard a few people stating how they didn’t want to get into the dogma of IVC ultrasound, that it wasn’t reliable, etc. The IVC doesn’t lie. It’s just not a recipe. The IVC findings have to be integrated into the rest of the echo graphic and clinical examination. Trying to use it as a single value is akin to using serum Na+ as a diagnostic test for volume. It works only sometimes.
Please spread among the POCUS non-believers. We’ll convert them, slowly but surely. But the sooner, the better for the patients. Again, there’s no excuse to practice acute care without ultrasound. It’s not right. I’m not saying every probe-toting MD is better than one without, but everyone would up their game by adding POCUS, once past the learning curve!
So today, I had the chance of having a private tutorial with Dr. Thomas Woodcock (@thomaswoodcock) about the glycocalyx and the revised Starling principles. For anyone interested in fluid resuscitation, this is an area you have to delve into. The basic principles we all learned (which are still being taught) are basically the physiological equivalent of the stick man we all started drawing as toddlers: overly simplified and far from an accurate representation of reality.
Now my first disclaimer is that I have been a colloid supporter for many years. My physiological logic for that had been to minimize the crystalloid spillover into inflamed/septic areas, particularly the lungs and abdomen, when those are the septic sources. However, I was likely misled by my education and lack of knowledge about the endothelium.
So I stumbled upon the whole glycocalyx thing a couple years ago, and this prompted me to try more enteral fluids – the only way fluids normally ever enter the vasculature – but little else. Aware that it’s there, but unsure what to do about it.
Now a year and a half ago, Andre Denault, my closest thing to a mentor, casually dropped the line to me about albumin not working. “Don’t use it. It doesn’t act the way we think it does.” But it was a brief chat, and I didn’t get to pick his brain about it. Just a few weeks ago, I discuss with Jon Emile (Kenny), and he’s coming to the same conclusion. Damn. I’m finding it a bit harder to hang on to my albumin use, which is beginning to look a bit dogmatic and religious.
Here is Tom Woodcock’s site and article – another must-read.
And here is my discussion (in two parts) with Tom (to skip the silence, skip forward to about 30 seconds into each – sorry my editing skills are limited!)
Bottom line?
Probably stick to isotonic crystalloids, and some hypertonics.
I was really psyched when Jon-Emile mentioned he would like to talk about the glycocalyx. I first blogged about it here, basically when I stumbled on the extensive literature on this huge organ we have been completely ignoring in terms of physiology and therapeutics. It lines our entire endothelium, which is where most of our therapeutic interventions go, and we only heard of it in passing, possibly in histology class as med 1’s. Hmmm. Anyhow, here, Jon-Emile and I talk about it a little, discuss possible clinical implications, but more importantly Jon mentions the relatively new blog of Dr. Thomas Woodcock (@thomaswoodcock), http://www.fluidtherapy.org, who is one of the pioneer clinicians who have studied the glycocalyx, and who is now trying to bridge the bench to the bedside.
I’ve been fortunate enough to get in touch with him and we’re planning to record some discussions soon.
So, in my view, the glycocalyx is a formidable force we have been ignoring, and have been damaging often with our interventions. I’m hoping to see some developments allowing glycocalyx assessment outside of the labs in order to give us the tools to reassess every fluid in terms of the relative damage it does to what is essentially the gatekeeper between the blood and the tissues.
thinking critical care 