In this Hurricane Sandy episode of the EMCrit podcast, I talk about the confirmation of two of my clinical prejudices.
Chloride Poisoning
So I've always preached that grabbing normal saline for every ED patient is poor thinking and poor practice. We discussed this topic in the 4th Acid-Base Podcast on Fluids. Up until now, I did not have great evidence for my prejudice; now at least, I have reasonably good evidence:
Major complications, mortality, and resource utilization after open abdominal surgery: 0.9% saline compared to Plasma-Lyte (Ann Surg. 2012 May;255(5):821-9)
Association Between a Chloride-Liberal vs Chloride-Restrictive Intravenous Fluid Administration Strategy and Kidney Injury in Critically Ill Adults (JAMA. 2012 Oct 17;308(15):1566-72)
Definitive? Nope, but it just seems like good medicine to treat fluids like any other drug and actually choose the ideal one for the clinical situation.
Resus.me Post: What’s with all the chloride? An assault on salt | Resus M.E!
Upate:
Association Between the Choice of IV Crystalloid and In-Hospital Mortality Among Critically Ill Adults With Sepsis
Karthik Raghunathan (Crit Care Med 2014 citation pending)
A Diversion on Osmolality
Peter Sherren made a great comment in the podcast on the Brain Code regarding my statement that lactated ringers is an inappropriate fluid in high ICP. So I had a bit of a think on the topic and then was baffled as to why LR has a Na of 130 and yet a Osm of 272-5.
Brian Hayes responded to a tweet on the topic with what is probably self-evident to everyone but me: the Osm calculation we use is actually a crappy short cut; all components of a fluid need to be calculated to get the real Osm. Yet, when I thought about this still further, I realized that what is written on the bag is not actually the in-vivo Osm effects. Instead, the Na is probably the key.
Want proof of this concept? D5W has an Osm of 252 on the bag, but the effective Osm is 0 as soon as your cells take up the glucose.
So can you use LR in high ICP, yes probably not too big a deal, but the net Osm effects will probably be to lower the serum Na and Osm. If you buy choosing the ideal fluid for acid-base, it probably makes sense to choose the ideal fluid for Osm as well. Maybe this prejudice will be verified 5 years from now with a real article.
Here is the article I mentioned on the Osm effects of LR on healthy volunteers: (Anesth Analg 1999;88:999 –1003)
Here is an Osm calculator from GlobalRPH.
A Diversion on the need for Conversion of the Buffer Bases
Want what I think is the ideal resus fluid? Mix this on the fly:
Ultimate Resus Fluid? 1 amp of 44.6 bicarb in 500 ml of NS makes 550 of total volume= Na 121.6 Cl 77 Bicarb 44.6 to extended out to 1 liter= Na 217 Cl 138.6 BiCarb 80 1.3% Balanced Saline solution
There is ABSOLUTELY no evidence for this. If someone wants to do the study, please just put in me in the authorship somewhere.
Pressure Poisoning
Now I can say it: 8 ml/kg Vt by IBW for ALL ED PATIENTS should be your starting dose.
Association Between Use of Lung-Protective Ventilation With Lower Tidal Volumes and Clinical Outcomes Among Patients Without Acute Respiratory Distress Syndrome – A Meta-analysis JAMA. 2012;308(16):1651-1659
Resus.me Post: Not just in ARDS | Resus M.E!
Like this episode? Then tweet the hell out of it
Confirmation of 2 clin prejudices is the basis of EMCrit 85 with hat tips to @PBSherren, @PharmERToxGuy and @cliffreid: http://t.co/w3Tr9KSQ
— the EMCrit Crew (@emcrit) October 29, 2012
Additional New Information
More on EMCrit
You Don't Understand the Osm Gap – Guest Post by Rory Spiegel(Opens in a new browser tab)
EMCrit Lecture – Dominating the Vent: Part I
EMCrit 237 – Vent & PreVENT – An Update
Additional Resources
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Professor
Nassau University Medical Center
No conflicts of interest (coi).
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Aaaaack! I was going to stroke out until you wrote “Definitive? Nope”. My blood pressure is bakc down and i probably only had a small bleed. Certainly not definitive, but the evidence is a mounting. Might be time to author that “Plea for Normalcy” essay. You know, normal pco2, normal pao2 in head injury, normal ventilation strategy, normalish bp in ich, normal volume in sepsis, now a more normal fluid in fluid resusc. Hmmm, making things normal seems like what we ought to be doing in most cases of critical anything?
trying hard to never utter any axiomatic statements that are not ready for prime time. and if i forget, you’ll be there to keep me honest, my friend.
Making things normal (“euboxia”) isn’t always the way to go however… You could put your patient in a different kind of box:
http://lifeinthefastlane.com/2010/01/dont-put-your-patient-in-a-box/
Chris
What are your thoughts about a solution of 1 lt of 1/2NS+ 2 amps of bicarb with regards to using a hypochloremic fluid/ high Osmolar fluid?
1/2 NS + 1 1/2 amps bicarb is an isotonic slightly alkalotic balanced solution. 2 amps would be fine as well. 2 Bags Isolyte/Plasmalyte for every bag of saline is not a bad way to go either.
I just noticed that there’s 2 flavors of Voluven.
Voluven (with Na 154, Cl 154)
Voluven balanced (Na 137, Cl 110, K 4, Acetate 34)
Never paid attention to this, my unit has the balanced one. I wonder if the CHEST study was done with one or the other, since the amount of Cl seems relevant to kidney injury…
Check in here after you look it up.
From the methods: “Patients were assigned to receive either 6% HES (130/0.4) in 0.9% saline (Voluven, Fresenius Kabi) or 0.9% saline”. I’m afraid we don’t have that level of detail, but it’s probably the unbalanced one… So is the difference in AKI due to Chloride poisoning or starch?
From the methods: “Patients were assigned to receive either 6% HES (130/0.4) in 0.9% saline (Voluven, Fresenius Kabi) or 0.9% saline”. I’m afraid we don’t have that level of detail, but it’s probably the unbalanced one since they mention it’s diluter in 0.9% saline… So is the difference in AKI due to Chloride poisoning or starch?
agree it was prob. the unbalanced. I’m not sure if it was the starch or not though there have been balanced starch studies that have also shown unimpressive results. I would love to see a balanced albumin study for septic shock.
Hi Scott. As always, great privilege listening to you. A few points of discussion on the topic of intravenous fluids. 1.The anions. Although lots of chloride may not be great for our patients the physiological effects of the other anions used in more “balanced” fluids also merits a little circumspection. Gluconate (that other plasmalyte buffer) it seems has not been rigorously studied. A little more is known about acetate – evidence of adverse immunological, metabolic and cardio-toxic effects led to its abandonment in renal replacement fluids in Australia and elsewhere not too long ago. Also interesting in this respect is… Read more »
Adam, Fantastic comments; I agree with you on all of your points. The surrogate buffer bases are all an unk quantity. That is why these two studies are important. We don’t know if LR or plasmalyte are “good”; we merely can now suspect (not confirmed yet) that they seem better than NS in the populations studied. This is why pt-important outcomes are so key. Brilliant acid-base folks like Kellum have believed for a while that hyperchloremia may actually be problematic, but as you mention, up until now there hasn’t been evidence. Now there is a bit, unless saline is causing… Read more »
Great podcast as always. The podcast was a bit unclear as to what would you use (assuming like in my dept only NS or LR no plasmalyte) for a DKA patient or a septic shock pt with lactic acidocis
If they are severe acidosis, LR would be a better choice than NS.
Hi EMCrit
In the pt in severe DKA with severe acidosis and high potassium should we stick to normal saline not Hartmanns as Hartmanns has potassium in it?
Thanks
Steve young
Swansea
Wales
Hey Scott, Having a great intellectual week following this post. Looking at your “ideal balanced” solution I see some potential side reactions. Ion pairing may become an issue. As you know all protanation states of the bicarb are gonna exist in solution. The pair of Na2CO3 may tie up some of your sodium thus effecting the overall deliverable sodium. While aqueous chemistry usually disreagrds side reactions and ion pairing this -2 charge carbonate ion WILL exist in solution and WILL bond up some sodium. Given the pH of the solution the concentration can be determined. It is likely to be… Read more »
Fascinating! The fluid has a larger buffer to still be balanced, so even if there was some sodium binding, the Na/Cl difference would still be >40 from my back-of-envelope calcs, correct?
Overall yes I expect to see a Na/Cl difference above the 40 limit. However Two considerations. 1. If you are doing a calculation you would want to account for Ion pairing, afterall you are doing a modified systematic treatment of equilibria so you do want to account for some. Assuming negligibility, assume <5% ,of your sodium loss due to pairing and you are still ok. 2. Le Chatliers principle, the more basic this solution the greater the concentration of Carbonate in solution therefore the more of the carbonate that is gonna look to get back to a neutral state, taking… Read more »
Great Podcast Scott. I quite like the mash up. I have to agree with Adam Drenzla’s comments, and he’s also written a small post on his topic having been inspired by you and Cliff here:
http://intensivecarenetwork.com/index.php/component/content/article/913-forum/401-drenzla-on-the-fluid-debate
After SAFE, and now CHEST, the logical next step for ANZICS CTG would be N/saline vrs a”balanced” solution…. But what that should be is still up for debate I guess. I do think a big, pragmatic MC RCT is the only way to settle this one.
Absolutely, Oli. I think ANZICS is one of the few groups that could get this done.
Scott, you’re killing me. I’ve spent the last several weeks going over all of the acid base podcasts you’ve posted plus this one.
It’s all good though, well worth the time!
Thanks for expanding my all too often cookbook ways.
Thanks buddy; sorry for the time suck : )
Is there such thing as an ‘ideal’ resus fluid to fit all situations? Wouldn’t it depend on the aetiology of both the water deficit and the associated acid/base electrolyte disturbances. And why bicarb? What if you have a severely volume-depleted bulimic with metabolic alkalosis. Furthermore, for shock associated with Type A lactic acidosis or DKA, the answer is to improve perfusion or halt ketogenesis – not give bicarb. In situations of iatrogenic hyperchloraemic metabolic acidosis, my understanding the issue is more with excessive chloride administration once adequate perfusion is established. Regarding the JAMA articles, was it just the chloride restriction… Read more »