EMCrit Podcast 44 – Acid Base: Part I

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 3 or 4 parts. They are segmented from a lecture I gave to my residents recently. Part II discusses the mathematics of acid base and Part III goes through actual problems. Part IV then discusses the acid-base of administered solution.

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.

After listening to the podcast, I recommend reading this article:

Kaplan LJ,Frangos S. Clinical review: Acid–base abnormalities in the intensive care
unit. Critical Care 2005;9(2):198
For the next part of the series, you will need a print out of this sheet:
EMCrit Acid-Base Sheet

Want to read more?

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

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Comments

  1. Matt Messa says:

    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

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

  3. MIke Jasumback says:

    Scott,

    No mp3 version????

    Mike

  4. Mike Jasumback says:

    Thanks Scott,

    I am I-literate! But I have a towel

    Mike

  5. Zach Webb says:

    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!

    • 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

      • Zach Webb says:

        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.

  6. Chris Fedoruk says:

    Hey Scott:

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

  7. Christopher Hapner says:

    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.

  8. Austin Johnson says:

    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

Trackbacks

  1. [...] [Click here to read more and watch the vodcast] [...]

  2. [...] 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 [...]

  3. [...] You should listen to Acid-Base Part I first. [...]

  4. [...] 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). [...]

  5. [...] 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 [...]

  6. The so-called answer to the 'Really Tricky ABG' challenge says:

    [...] 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). [...]

  7. [...] 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 [...]

  8. [...] 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 [...]

  9. Blodgas | Kurs i Akutsjukvård says:

    [...] 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 [...]

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

  11. [...] EMCRIT – Blood Gases Part 1 [...]

  12. […] 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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