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You are here: Home / EMCrit-RACC / EMCrit Podcast 44 – Acid Base: Part I

EMCrit Podcast 44 – Acid Base: Part I

April 11, 2011 by Scott Weingart 50 Comments

I have spoken about it for a while, but I've finally gotten it done: the acid-base podcast.

The podcast is going to be in 5 parts. They are segmented from a lecture I gave to my residents recently.

  • Part I lays out the background of the quantitative approach
  • Part II puts it in mathematical terms to allow calculation of acid base status
  • Part III takes you through some real world examples
  • Part IV discusses the Acid-Base Effects of IV Fluids
  • Part V specifically discusses some of the Bicarb Controversy

The Acid Base Series

  • EMCrit Podcast – Acid Base Ep. 7 – Bicarb Updates, Quantitative Approach, and Prof. David Story
  • Podcast 97 – Acid-Base VI – Chloride-Free Sodium
  • Podcast 96 – Acid Base in the Critically Ill – Part V – Enough with the Bicarb Already
  • EMCrit Podcast 50 – Acid Base Part IV – Choose the Solution Based on the Problem
  • EMCrit Podcast 46 – Acid Base: Part III
  • EMCrit Podcast 45 – Acid Base: Part II
  • EMCrit Podcast 44 – Acid Base: Part I
For the next part of the series, you will need a print out of this sheet:
EMCrit Acid-Base Sheet

 

This lecture discusses a quantitative approach to acid base management. This is also known  as the Fencl-Stewart approach, the strong-ion approach or the physicochemical approach. It provides explanations for why acid base disorders occur in human pathophysiology. The classic method used in the USA is the Henderson-Hasselbalch (misspelled on my slides) approach. I find this method to provide no comprehensive explanation for why things are as they are. Through the quantitative approach, you can also understand the H&H approach and continue to use it with new insight.

This first part deals with the preliminaries. Part II will go into clinical applications.

For the next part of the series, you will need a print out of this sheet:
EMCrit Acid-Base Sheet

Want to read more?

  • AcidBase.org
  • Anaesthetist.com
  • facing-acid-base-disorders-in-the-third-millennium
  • Propofology Quick-Ref PDF

After listening to the podcasts, I recommend reading these articles

  • Kaplan LJ,Frangos S. Clinical review: Acid–base abnormalities in the intensive care unit. (Critical Care 2005;9(2):198)
  • Clinical review The meaning of acidbase abnormalities in the intensive care unit
  • Facing Acid-Base Abnormalities in the Third Millenium
  • (Am J Emerg Med 2015;33(3):378)  Evaluation of acid-base status in patients admitted to ED—physicochemical vs traditional approaches
  • Story D. (Open Mind) Stewart Acid-Base: A Simplified Bedside Approach. Anesthesia and Analgesia, 2016 (ePub ahead of print)
  • 10 Acid Base Assertions
  • A critique of Stewart and Bicarb approach

Need an Audio Only Version?
Acid Base Part I MP3 [Play]
(Right Click and Choose Save as)

…

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Podcast: Play in new window | Download (Duration: 25:00 — 43.8MB) | Embed

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  • Author
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Scott Weingart

An ED Intensivist from NY. No conflicts of interest (coi).

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Filed Under: EMCrit-RACC Tagged With: acid base, acid-base-series, acidosis, albumin, anion, archive podcasts, bicarbonate, cation, Fencl-Stewart, lactate, lactic acid, physicochemical, podcasts, strong-ion, weak acids

Cite this post as:

Scott Weingart. EMCrit Podcast 44 – Acid Base: Part I. EMCrit Blog. Published on April 11, 2011. Accessed on December 14th 2019. Available at [https://emcrit.org/emcrit/acid-base-i/ ].

Financial Disclosures

Unless otherwise noted at the top of the post, the speaker(s) and related parties have no relevant financial disclosures.

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This Post was by the EMCrit Crew, published 9 years ago. We never spam; we hate spammers! Spammers probably work for the Joint Commission.

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Chris Nickson
Guest
Chris Nickson

(Na + K+ Mg + Ca) – (Cl + lactate) = Answer to the Ultimate Question of Life, the Universe, and Everything
(when SID is normal)
C

Vote Up2Vote Down  Reply
8 years ago
Scott Weingart
Author
Scott Weingart

I thought 42 was the ultimate answer to everything; remember your towel.

Vote Up1Vote Down  Reply
8 years ago
Chris Nickson
Guest
Chris Nickson

Exactly (if you fudge the numbers a little)
😉
C

Vote Up1Vote Down  Reply
8 years ago
trackback
ABG app review | keepcaring

[…] A while back I asked the twitterverse whether anyone could recommend a good app for arterial blood gas (ABG) interpretation. The deafening silence showed me that (a) I have very few followers and (b) if I want an ABG app review, I have to write it myself. Hence this blog post. A few preliminary remarks are in order. If you don’t already know how to interpret tricky blood gases, go listen to the four-part podcast series by Scott Weingart  part one can be found here […]

Vote Up1Vote Down  Reply
7 years ago
trackback
Acid Base: Part I « The Central Line

[…] [Click here to read more and watch the vodcast] […]

Vote Up0Vote Down  Reply
8 years ago
Matt Messa
Guest
Matt Messa

Hey Scott,

From what I can tell, the first day your new Podcast comes out, it is not yet on the i-Tunes list. So the only way to listen to it is as a quicktime file on my PC. Is there another way? I usually just have to wait painfully to see that i-tunes has your latest but this is sometimes a day or two. Thanks for your hard work!

Matt

Vote Up0Vote Down  Reply
8 years ago
Scott Weingart
Author
Scott Weingart

Refresh button on the bottom right of your itunes podcast screen will cause instant updates.

Vote Up0Vote Down  Reply
8 years ago
MIke Jasumback
Guest
MIke Jasumback

Scott,

No mp3 version????

Mike

Vote Up0Vote Down  Reply
8 years ago
Scott Weingart
Author
Scott Weingart

Added inside the post, just for you Mike.

Vote Up0Vote Down  Reply
8 years ago
Mike Jasumback
Guest
Mike Jasumback

Thanks Scott,

I am I-literate! But I have a towel

Mike

Vote Up0Vote Down  Reply
8 years ago
Zach Webb
Guest
Zach Webb

Great first part of the acid-base lecture. In fact, great website overall.

I start 3rd year of med school in July, and these lectures will no doubt improve my understanding of medicine and what goes on in the hospital.

Thanks!

Vote Up0Vote Down  Reply
8 years ago
Scott Weingart
Guest
Scott Weingart

Zach, thanks for the feedback. Get back to us and let us know how this version of acid-base fits in to what you learned years 1-2.

scott

Vote Up0Vote Down  Reply
8 years ago
Zach Webb
Guest
Zach Webb

Here they teach us H-H pretty religiously. What’s CO2 doing? What’s bicarb doing? What’s the pH? A little bit on anion gap. It all stays pretty superficial, and every discussion leaves you wanting more.

So, it’s nice to get a fresh perspective on the topic. Thanks again.

Vote Up0Vote Down  Reply
8 years ago
trackback
The LITFL Review 015 - Life in the FastLane Medical Blog

[…] spot this week go’s to Scott over @ EMCrit for tackling the tough topic of Acid Base in the Critically Ill. Part 1 in this series of podcast discusses a quantitative approach to acid base management. A […]

Vote Up0Vote Down  Reply
8 years ago
Chris Fedoruk
Guest
Chris Fedoruk

Hey Scott:

I light of this paper, do you guys still use NS at Hurst, or are you prefering LR. Just curious.

Vote Up0Vote Down  Reply
8 years ago
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[…] You should listen to Acid-Base Part I first. […]

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[…] in blood gas interpretation and acid-base – then you should check out the latest episode of EMCrit which has a technique which might be new to you (NOT the old Henderson-Hasselbach approach). […]

Vote Up0Vote Down  Reply
8 years ago
Christopher Hapner
Guest
Christopher Hapner

This lecture is very helpful for my understanding of Acid/base coming from a 1st year. I really enjoy coming to the website to clarify and solidify many of the concepts we are covering in class.

Vote Up0Vote Down  Reply
7 years ago
Scott Weingart
Author
Scott Weingart

thanks for the feedback, Christopher.

Vote Up0Vote Down  Reply
7 years ago
trackback
The so-called answer to the 'Really Tricky ABG' challenge

[…] Using the physicochemical/ Stewart approach, the Strong Ion Difference (normal is 38) is markedly low (Na – Cl = 146 – 129 = 17). The causes of this are the same as the causes of NAGMA (see also EMCrit — Acid Base in the Critically Ill – Part I). […]

Vote Up0Vote Down  Reply
7 years ago
trackback
ABG app review | My Website

[…] A while back I asked the twitterverse whether anyone could recommend a good app for arterial blood gas (ABG) interpretation. The deafening silence showed me that (a) I have very few followers and (b) if I want an ABG app review, I have to write it myself. Hence this blog post. A few preliminary remarks are in order. If you don’t already know how to interpret tricky blood gases, go listen to the four-part podcast series by Scott Weingart  part one can be found here […]

Vote Up0Vote Down  Reply
7 years ago
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Medical myths debunked No 2: Everything about ABGs « drcrunch

[…] which does not take into account important determinants of blood pH.  I recently came across EmCrit’s  podcast on Acid Base and it has revolutionised my […]

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7 years ago
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[…] del tycker att detta är ett betydligt enklare sätt att tänka. Se, lyssna och lär från emcrit del I, II, III och IV Share this:TwitterFacebookGillaGillaBe the first to like this. This entry was […]

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7 years ago
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Acid Base and DKAs, Bs, and Cs | Targeted Utilization of the Best Education in EM

[…] Shownotes: https://emcrit.org/podcasts/acid-base-i/, https://emcrit.org/podcasts/acid-base-part-ii/, https://emcrit.org/podcasts/acid-base-part-iii/, […]

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6 years ago
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[…] Shownotes: https://emcrit.org/podcasts/acid-base-i/, https://emcrit.org/podcasts/acid-base-part-ii/, https://emcrit.org/podcasts/acid-base-part-iii/, […]

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6 years ago
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Acid Base | Critical Care Practitioner

[…] Scott Weingart starts a series of podcasts discussing acid base and its interpretation. Starts off by NOT using the Henderson-Hasslebach equation! Link here […]

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6 years ago
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The ED Arterial Blood Gas (ABG) | EmergencyPedia

[…] EMCRIT – Blood Gases Part 1 […]

Vote Up0Vote Down  Reply
6 years ago
Austin Johnson
Guest
Austin Johnson

Hey Scott, a quick question (but afraid its a long answer)
When the SID is decreased by giving NS, where does the H+ come from? Why does the decreased SID really cause an acidosis? It can’t be from the H2CO3 dissociating to H+ as that would also increase your HCO3-, right? I have been reading everything on Stewart’s approach that we have access to (Kaplan, Morgan, etc) but no one really explains it (and we can’t get a copy of the Stewart paper).
Thanks
Austin

Vote Up0Vote Down  Reply
6 years ago
Scott Weingart
Author
Scott Weingart

Short answer–
Go right to the source:
http://www.acidbase.org/index.php?show=sb&action=explode&id=22&sid=24
Stewarts book for free. Short answer is H+lives attached to water molecules just waiting to emerge.

Vote Up0Vote Down  Reply
6 years ago
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Ventilation and Perfusion | Welcome to Jeremy Jaramillo's Blog

[…] EMCrit Podcast 44 – Acid Base: Part I […]

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6 years ago
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The so-called answer to the 'Really Tricky ABG' challenge

[…] Using the physicochemical/ Stewart approach, the Strong Ion Difference (normal is 38) is markedly low (Na – Cl = 146 – 129 = 17). The causes of this are the same as the causes of NAGMA (see also EMCrit — Acid Base in the Critically Ill – Part I). […]

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6 years ago
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[…] Podcast 44 – Acid Base: Part I […]

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[…] If you are interested in blood gas analysis then why not try AnaesthesiaMCQ or if you are feeling like a challenge listen to all five podcasts on acid-base from the EMCRIT podcast […]

Vote Up0Vote Down  Reply
4 years ago
Dr. O. Ballo
Guest
Dr. O. Ballo

My name is Olivier, MD at the university hospital of frankfurt.

So when you give diuretics (Furosemid, Torasemid) you will get low serum sodium leading to a small SID and thus acidosis but on the other hand there will be more sodium in the Collecting duct system in the kidney that will be taken into the principal cells causing a Transepithelial potential difference that will lead to H+ excretion by the H+-ATPase.

So will diuretics rather cause azidosis or alcalosis?

Vote Up0Vote Down  Reply
4 years ago
Leo
Guest
Leo

Hi Olivier,
it might not be a sound explanation but if you consider that the loop diuretics inhibit the NKCC which has a stoichometry of 1:1:2, you might loose more chloride than sodium and end up with a hypochloremic alkalosis.
I took this argument from this article in the NEJM: N Engl J Med. 2015 Jan 22;372(4):391-2

Vote Up0Vote Down  Reply
3 years ago
trackback
Dr. Michael Chansky: Acid-Base (Made Easy) - MarylandCCProject.org

[…] Part 1 […]

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4 years ago
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[…] Paeds Resus “Nails”.  However, if you follow the blog or are a fan of the excellent Emcrit series on acid-base therapy then you will know that “normal” SALINE is in fact a nett acidotic fluid which will […]

Vote Up0Vote Down  Reply
4 years ago
James Garvey
Guest
James Garvey

Is there any way of estimating how much a mild element of renal failure would account for a certain strong ion gap?
Could you use the urea / BUN value to calculate this?

Vote Up0Vote Down  Reply
3 years ago
Scott Weingart
Author
Scott Weingart

nope
and mild shouldn’t do it. that usually causes SID effects. To cause SIG, there is significant renal damage

Vote Up0Vote Down  Reply
3 years ago
Stacy Turner
Guest
Stacy Turner

Hi Scott.
In addition to this, is it possible to add a ketone concentration to our ‘unmeasured anions’ (to ensure there are no other unmeasured anions other than ketones)?
I can’t find a way to do this. From what I’ve read, serum ketone testing only measures acetoacetate and the ratios of hydroxybutyrate:acetoacetate:acetone vary, so ketone measurement is only semi-quantitative. Is this correct?
Thanks,
Stacy

Vote Up1Vote Down  Reply
3 years ago
trackback
Base Excess

[…] hole you’re willing to travel, I highly recommend EMCrit’s amazing talk on Acid-Base (HERE), along with these other excellent […]

Vote Up0Vote Down  Reply
3 years ago
Leo
Guest
Leo

Dear Scott,
I just discovered your great blog a few month ago and I’m trying to work my way through it now.
Reading your Acid-Base-sheet I came up with a question with a question of no practical implications but i would be happy if someone could come up with a good explanation:

You wrote that if the urine anion gap is negative one can rule out RTA. I found a paper (N Engl J Med. 2015 Jan 8;372(2):195 ) that put proximal RTA with a negative UAG. On the other hand Medline goes with you, on uptodate i could not find a clear statement. In my opinion a positive UAG would make sense since RTA II individuals will not have increased NH4-excretion and the HCO3 in the urine will lower the Cl-conc.

Could anyone comment on this: proximal RTA with positive or negative UAG, and why?

Thank a lot,Leo

Vote Up0Vote Down  Reply
3 years ago
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[…] of how to perform the calculations at the bedside. For further learning I suggest visiting the Acid-Base section on the EMCrit Website. Details of the Acid-Base Calculator App can be found […]

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1 year ago
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Vote Up0Vote Down  Reply
4 months ago

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