Fluid selection is always a controversial topic. I polled twitter recently and was surprised to find an almost even division between a normal saline versus balanced crystalloid as a resuscitative fluid:
what fluid would you use to resuscitate an average patient with no electrolyte abnormalities?
— 𝙟𝙤𝙨𝙝 𝙛𝙖𝙧𝙠𝙖𝙨 (he/him) 💊 (@PulmCrit) June 24, 2019
Based on this polling data, 42% of you will hate this chapter. It's a good thing I'm not running for president.
Seriously though, fluid selection remains controversial. This chapter presents an approach which makes sense physiologically and is supported by a substantial amount of animal and human data.
This is a challenging topic because the effect size of the interventions are extremely small, which makes it difficult to prove hard clinical endpoints in an RCT. However, when leveraged over thousands of patients who are treated with fluid, even a tiny effect size will eventually have meaningful clinical consequences.
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I do not have access to 1L of D5W in my setting. So what i often do is to add 70 ml of 8.4% NaHCO3 into my 500ml of D5W (140ml in 1L of D5W). However, i do occasionally come across patient with sepsis complicated with hyponatremia and AKI and met.acidosis. So how do you go about regarding this ? Is isotonic saline too hypotonic in this setting and therefore may worsen the hyponatremia?
1) isotonic saline isn’t hypotonic (it’s hypertonic) – but it’s pretty close to normal tonicity so it generally doesn’t have a big effect on sodium
2) if someone is hypotonic and has AKI and you want to give them bicarb you could just give some ampules of hypertonic bicarbonate as that will fix both problems (assuming that you’re trying to increase the tonicity)
I believe the table comparing Isotonic and Hypertonic Bicarbonate has the 8.4% and ~1.3% reversed.
thanks so much for pointing out that error – it’s fixed now
Hi,
I was wondering if you initiate bicarb therapy as long as the PH is below 7.30 or at lower level. The reason I am asking is because “uptodate” does not recommend bicarb therapy before the PH is below 7.10 and 7.20 when there is a coinciding AKI as well. They mention there is a risk, of among other things, intracellular acidification when you raise the PH. What is your opinion about that ?
Wonderful post, I am really glad I found this “treasure Box” of information!
Link to to the text in uptodate:
https://www.uptodate.com/contents/approach-to-the-adult-with-metabolic-acidosis?search=non%20anion%20gap%20metabolic%20acidosis&source=search_result&selectedTitle=1~111&usage_type=default&display_rank=1#H17
they seem to be trying to create a blanket statement regarding when to treat metabolic acidosis, which in my view is impossible. for example
– for diabetic ketoacidosis, bicarbonate shouldn’t be given regardless of pH (more on this here:
https://emcrit.org/pulmcrit/bicarbonate-dka/)
– for NAGMA, bicarbonate should be given to repair the bicarb deficit (even if the pH is being maintained for example with a compensatory respiratory alkalosis)
We will explore the treatment of these different problems in various chapters of the IBCC. Blanket rules don’t work.
Sodium lactate is an acid wrt plasma – SID of zero! Probably equal to saline in anhepatic phase, metabolism to HCO3 makes it neutral. Hydrogen lactate is of course far more acidic.
What do you do for carrier fluids to give drugs, drips to keep lines open? In fluid-aware icu’s these account for the majority of volume given. Ideally, we should have a balanced and hypotonic (salt balance!) carrier.
Best regards
Lactate is rapidly converted into bicarb so it’s an alkali in the body
We’re usually forced to use saline as a vehicle for various infusions. Our ICU pharmacists can sometimes help us optimize things (e.g. a drug can be reformulated in either normal saline or D5W – so choosing D5W can avoid the chloride load).
Usually by the time NaHCO3 is being considered the pts already been “volume resuscitated” – they got their 30cc/kg in the ED, 250/hr + boluses in the OR, or their 100/hr IVF for 3 days on the floors. And many/most AKI pts with significant acidosis/hyperkalemia present hypervolemic anyway and still get this fluid in the ED. Its too often the ICU gets an acutely hypovolemic acidotic hyperkalemic patient in the ICU who MIGHT benefit from NaHCO3 as the resuscitating fluid. Instead what happens is these eu-hyper-volemic pts get put on NaHCO3 drips by well-meaning providers who think the NaHCO3 has… Read more »
Great post Josh!
For patients with either saline-induced hyperchloremic acidosis or metabolic acidosis (NAGMA & AGMA) I have been using a McGuyvered fluid that provides some bicarb, that maintains the SID and provides a reasonable dose of bicarb.
Recipe:
IL D5W – Remove 140 mL
Add 200 mL of 3% NaCl = ~ 100 mmol Na/100 mmol Cl
Add 40 mL of Bicarb (8.4%) = 40 mmol Na/40 mmol Bicarb
Final: Na 140 mmol; Cl 100 mmol; Bicarb 40 mmol
Hasn’t killed anyone yet, and provides a nice slow correction .
I’m going to try this recipe on my next shift!
That’s a neat solution, but it’s not my preferred approach. I don’t like customizing the solutions too much for a few reasons (1) can cause errors in formulation (2) doesn’t allow you to titrate at the bedside (3) your pharmacists may kill you So my preferred approach here (if you’re trying to infuse a fluid with SID of 40) would be a *simultaneous* infusion of two solutions (you could Y-site them together and use a single IV) (a) Isotonic bicarbonate (1.4%) at 36 ml/hour (b) Normal saline at 100 ml/hour The two fluids will mix in the patient’s body to… Read more »
Oh God… I’m going to have to agree with Josh’s point 3… In an individual sense I understand that it can be done safely… but when this is done 100 times, 1000 times, when interns and residents start seeing it done… what is an acceptable error rate? Because Baxter’s is incredibly low. How are you going to explain to a patients family that it was worth is to pull a MacGruber because you wanted 40 mmol of Bicarb versus the 27 of acetate in Plasmalyte? I’m speaking from experience… In the last 10 years, I have screwed up at least… Read more »
My pharmacy provides a 1meq/1ml concentration of bicarbonate to be run at a rate of 10-20 meq an hour via a CVC in volume overloaded patients, generally trying to match what they would receive in the more dilute version.. These are usually very sick patients, often in need of HD/CRRT for acidosis and overload, but maybe not tolerating due to profound shock. I understand the concerns of hypertonic bicarbonate administration in general, but would its use in this fashion be theoretically any more or less harmful. Thank you
Hypertonic bicarb is hypertonic bicarb. Running it slowly will avoid rapid shifts in sodium or pCO2 levels, which is good, but at the same time it won’t provide a ton of bicarb (e.g. you’ll be giving the equivalent of an ampule ever 2.5-5 hours). Depending on the clinical context that could be perfect, or it could be insufficient – depends on the patient. Overall this seems like a totally reasonable strategy for the right patient.
Please be careful when intepreting AB balance using HH equations, AG or BE. Those models are useful in practice, but explanations are chemicaly and physically wrong. When dissolved in water, CO2 equilibrium is between CO2 (dissolved gas), HCO3 and carbonic acid. Please read about total CO2 content, which adds HCO3 to pCO2.. They are all the same! Bicarb changes pH because it is eliminated and Sodium stays increasing SID (please read Stewart’s textbook). As pH changes, CO2 equilibrium shifts towards more HCO3, therefore measured HCO3 will even increase (due to equilibrium shift). Yoi should know that for.the very same reason,… Read more »
Hi Josh, great concept. One thing I thought about: would it be reasonable to use isotonic bicarb in patients with DKA? Probably potassium substitution would be also needed. But wouldn’t that be the perfect fluid for the patient with severe DKA and a pH of 7.0? I am a resident in Austria and we use a lot of Elomel isoton, which is quite similar to plasmalyte in the US. A problem with isotonic bicarb is that here in Austria nobody knows about this. So when you tell the nurses you want 3 amps of bicarb 8.4 percent in 1000ml of… Read more »
Hi
I would love to give LR rather than NS in almost all situations, at my new hospital I get a popup warning when I try to give it to anyone getting ceftriaxone, is the risk of a calcium precipitate legit in adult patients? Ceftriaxone seems to be the default abx for our common caps and utis so it is seriously limiting my LR use