# Sodium Bicarb.



## Sasha (Jan 23, 2009)

I've asked all my instructors and preceptors, and I've gotten answers that range from "Uhhhh.. hmm.. I don't know" to "Well, our protocols say to push this much, so we do." So I'm hoping someone here can enlighten me. 

I don't get sodium bicarb. You push it if someone is acidodic, correct? But with out lab values or something, which is not obtainable in the field, how do you know that by pushing sodium bicarb, it's not too much and you're not just sending them from acidosis to alkalosis? Is alkalosis less damaging to cells and tissue and such that it's a better state to be in than acidosis?


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## jrm818 (Jan 23, 2009)

bicarb is a buffer, meaning it acts to resist changes in pH outside of the normal range, rather than simply raising pH under all circumstances.  This is where acid/base homeostasis comes into play - the simplified version is that as the body becomes acidodic the [H]+ ions react with the bicarbonate anion to form carbonic acid and eventually water and CO2, which is blown off by the body. 


HCO3- + H+  ---> H2O + CO2 (through H2CO3 as an intermediate)

 If the pH shifts too much towards alkaline, the reaction operates in reverse and produces H20/[H]+.  It is the nature of the chemicals that acidic conditions encourage the reaction above, and alkaline conditions encourage the reverse reaction.

Basically it's self correcting - bicarb is the bodies way of maintaining stable pH, and adding more simply increases the bodies ability to cope with excess acid. 

for more

http://www.anaesthesiamcq.com/AcidBaseBook/ab2_2.php

or wikipedia


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## JPINFV (Jan 23, 2009)

^
I think the key quote from that link is this:


> On chemical grounds, a substance (NaH2CO3) with a pKa of 6.1 should not be a good buffer at a pH of 7.4 if it were a simple buffer. The system is more complex as it is ‘open at both ends’ (meaning both [HCO3] and pCO2 can be adjusted) and this greatly increases the buffering effectiveness of this system. The excretion of CO2 via the lungs is particularly important because of the rapidity of the response. The adjustment of pCO2 by change in alveolar ventilation has been referred to as physiological buffering.
> The bicarbonate buffer system is an effective buffer system despite having a low pKa because the body also controls pCO2



Here's another good link: http://www.chemistry.wustl.edu/~edudev/LabTutorials/Buffer/Buffer.html that I found today.


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## jrm818 (Jan 23, 2009)

right...a buffer will have a sort of "set point" that it will direct the pH. the set point is determined by the chemistry of the buffer itself...whatever the pH is when the acid/base reaction is in equilibrium.  

The setup in the body is a bit more complicated, as the end products can all be removed  or added (CO2 by respiration, bicarb via renal excretion or production...and renal activity in acid/base homeostasis is a whole topic unto itself).  That allows the "set point" to be precisely controlled.

basically, what he said ^


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## JPINFV (Jan 23, 2009)

jrm818 said:


> right...a buffer will have a sort of "set point" that it will direct the pH. the set point is determined by the chemistry of the buffer itself...whatever the pH is when the acid/base reaction is in equilibrium.



The thing with bicarb (which I honestly didn't realize till now) is that the set point for the buffer system is about a pH below the ideal physiological point.


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## piranah (Jan 23, 2009)

as far as I have been taught... there are 3 buffers in the body and they range from fastest reaction to slowest....Bicarb being the fastest,exhalation being the second, and renal being the third....i would never giv Bicarb unless it was a long state of cardiac arrest(due to the shutdown of the buffer system), and a TCA overdose(trycyclic antidepressant)......as for use on metabolic acidosis for any reason unknown.....i would not, just because the acid base balance is so sensitive its not worth the risk in the pre-hospital setting....my 2cents


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## JPINFV (Jan 23, 2009)

To be fair, though, the renal system and respirtory system are essentially adjusting the bicarb buffer system via Le Chatelier's principle.


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## MSDeltaFlt (Jan 23, 2009)

Sasha said:


> I've asked all my instructors and preceptors, and I've gotten answers that range from "Uhhhh.. hmm.. I don't know" to "Well, our protocols say to push this much, so we do." So I'm hoping someone here can enlighten me.
> 
> I don't get sodium bicarb. You push it if someone is acidodic, correct? But with out lab values or something, which is not obtainable in the field, how do you know that by pushing sodium bicarb, it's not too much and you're not just sending them from acidosis to alkalosis? Is alkalosis less damaging to cells and tissue and such that it's a better state to be in than acidosis?



God, I love the internet, Sasha.  Here's what I found on emedicine's website.


http://emedicine.medscape.com/article/906440-treatment

**********************************************************

*The general recommendation is to replace only half of the total bicarbonate deficit* during the first few hours of therapy.
*Do not overestimate or overcorrect the bicarbonate deficit. Rapid infusion of bicarbonate and overcorrection of the metabolic acidosis can lead to complications such as tetany, seizures, and hypokalemia by worsening the preexisting hypocalcemia and hypokalemia*.
Doses of bicarbonate exceeding 1 mEq/kg per dose may lead to an alkaline overshoot. For each 0.1 increase in pH, oxygen availability may decrease by 10% because of the shift of the oxygen-hemoglobin dissociation curve to the left.
Administered bicarbonate is dissociated into carbon dioxide and water.
*Carbon dioxide diffuses through the blood-brain barrier, whereas bicarbonate does not; this may lead to a paradoxical CNS aci*dosis.
Parenteral forms of sodium bicarbonate are available as 4% (1/2 strength) or 8% solutions. The sodium load can be significant when multiple bolus doses are administered.
If hypernatremia is a concern, consider continuous infusion of sodium bicarbonate as part of the maintenance intravenous solution. For example, 34 mEq/L of sodium bicarbonate can be added to a 0.22% sodium chloride solution to make up a 0.45% salt solution for maintenance intravenous therapy.

**********************************************************

Nothing is going to work in an either an acidic medium or an alkalotic medium.  You only want to bring back *balance*.  At least as best as possible.

Hope this helps.


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## Veneficus (Jan 23, 2009)

*resources that might help*

not much I can add to what everyone else here has said, but if you want some good resources:

lippincotts illustrated reviews of biochemistry and pharmacology are easy reads and have saved me more than a few times.

For your instructor I suggest:

Garrett and Grisham Principles of Biochemistry with a Human Focus. 
(an extremely difficult read but a suitable punishment for somebody teaching who gives you such cop out answers)


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## Ridryder911 (Jan 23, 2009)

Just to make a point, this type of question was on a normal ACLS course (back when ACLS was legitimate 70's & 80's). One was supposed to understand the oxyhemoglobin disassociation curve and the 20:1 ratio, etc. of ABG interpretation. 

My how times have changed and EMS and resuscitation requirements have been diluted and watered down.


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## BLSBoy (Jan 24, 2009)

I was also taught 3 mEqs in a HHN for inhalation injuries secondary to chlorine inhalation.


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## Veneficus (Jan 24, 2009)

Ridryder911 said:


> Just to make a point, this type of question was on a normal ACLS course (back when ACLS was legitimate 70's & 80's). One was supposed to understand the oxyhemoglobin disassociation curve and the 20:1 ratio, etc. of ABG interpretation.
> 
> My how times have changed and EMS and resuscitation requirements have been diluted and watered down.


double post, pay no attention to this one


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## Veneficus (Jan 24, 2009)

Ridryder911 said:


> Just to make a point, this type of question was on a normal ACLS course (back when ACLS was legitimate 70's & 80's). One was supposed to understand the oxyhemoglobin disassociation curve and the 20:1 ratio, etc. of ABG interpretation.
> 
> My how times have changed and EMS and resuscitation requirements have been diluted and watered down.



The ACLS EP course isn't bad I think. it's not perfect, but I think all of those 2 day courses are not meant to teach but show people what to do until somebody who knows what to do shows up.


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## maxwell (Jan 30, 2009)

Can of worms!  I like it!  Short and sweet.  Sodium bicarbonate is like a school voucher.  It makes the numbers look better, but doesn't fix the underlying problem!  

NaHCO_3 is good for hyperkalemic patients (of course with the rest of the drug box we throw at them) - but for acidosis?  No - don't do it.  It improves the intravascular pH but tanks the intracellular pH.  Bad news.  Field NaHCO_3, in my opinion should be left to hyperkalemia.  

"But what if my patients acidotic -all of their enzymes and receptors are denatured - how will other drugs work?"  - Well, yes you're right.  Some drugs require a normal pH!  So fix what's making them acidotic.  Intubate them, for example.


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## Ridryder911 (Jan 30, 2009)

maxwell said:


> Can of worms!  I like it!  Short and sweet.  Sodium bicarbonate is like a school voucher.  It makes the numbers look better, but doesn't fix the underlying problem!
> 
> NaHCO_3 is good for hyperkalemic patients (of course with the rest of the drug box we throw at them) - but for acidosis?  No - don't do it.  It improves the intravascular pH but tanks the intracellular pH.  Bad news.  Field NaHCO_3, in my opinion should be left to hyperkalemia.
> 
> "But what if my patients acidotic -all of their enzymes and receptors are denatured - how will other drugs work?"  - Well, yes you're right.  Some drugs require a normal pH!  So fix what's making them acidotic.  Intubate them, for example.



That's all good if it respiratory acidosis, but not all acidosis are respiratory. Again, treat the patient accordingly. 

R/r 911


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## firecoins (Jan 30, 2009)

Veneficus said:


> double post, pay no attention to this one



Than don't pay any attention to the man behind the curtain. That is all.


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## Jon (Jan 30, 2009)

Ridryder911 said:


> Just to make a point, this type of question was on a normal ACLS course (back when ACLS was legitimate 70's & 80's). One was supposed to understand the oxyhemoglobin disassociation curve and the 20:1 ratio, etc. of ABG interpretation.
> 
> My how times have changed and EMS and resuscitation requirements have been diluted and watered down.


I'm going to take a wild guess and say you were an instructor for that curriculum, too.

Anything you haven't done?




Bicarb and the acid/base balance has been a big discussion in my class on a regular basis. I understand it well enough, but I can't draw out the chemical formulas here.


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## JPINFV (Jan 30, 2009)

H2O+CO2<->H2CO3<->H+ + NaHCO3


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## maxwell (Jan 31, 2009)

Ridryder911 said:


> That's all good if it respiratory acidosis, but not all acidosis are respiratory. Again, treat the patient accordingly.
> 
> R/r 911



You're right - that's for respiratory acidosis.  However, true a metabolic acidosis can't be definitively diagnosed in the field.  Keep bicarb sacred!


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## Ridryder911 (Jan 31, 2009)

maxwell said:


> You're right - that's for respiratory acidosis.  However, true a metabolic acidosis can't be definitively diagnosed in the field.  Keep bicarb sacred!



Neither can respiratory acidosis either yet we try to tx it. Alike respiratory, metabolic also has clinical symptomatology than indicate the need of correcting it. Also dialysis patients can be treated as one should be able to get a recent lab value.

R/r 911


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## emtbill (Feb 1, 2009)

Ridryder911 said:


> Neither can respiratory acidosis either yet we try to tx it.



How useful/accurate is sidestream capnography for determining respiratory acidosis? Even if it was useful I don't see myself giving bicarb for a presumed acidemia stemming from a respiratory problem. Oxygen seems like a better intervention.


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## Ridryder911 (Feb 1, 2009)

Remember, Oxygen is the first line not the whole line treatment regime. 

R/r 911


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## Hastings (Feb 1, 2009)

Sodium Bicarb is responsible for every complete cardiac arrest recovery that I've had. On patients that are in cardiac arrest because they skipped dialysis (very common around here), it's a wonder drug. From Asystole to Sinus with a pulse almost instantly. Very selective use, but for that purpose, it's golden.

If you ever have a renal patient in cardiac arrest and the regular ACLS bit isn't working, push Sodium Bicarb and Calcium Chloride. Again, never seen it fail in that specific case.


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## emtbill (Feb 2, 2009)

The normal stimulus to breathe is a high level of carbon dioxide. If one alkalizes the blood incorrectly when acidosis is not present the H2O+CO2<->H2CO3<->H+HCO3 equilibrium will become imbalanced and the patient may become apneic. How do you reconcile this with the inability to determine acidosis in the field? The only signs and symptoms of this I can think of would be hyperventilation, which may be the patient trying to blow off excess CO2 from acidemia, or it might just be an anxious dyspneic patient whose labs are normal. Either way, I think improving ventilation if necessary with positive pressure and oxygenation with bronchodilators and supplemental oxygen would be a better treatment. Am I just wrong here? It's just that I was never taught to think about bicarb for respiratory distress, and the theory of its benefit in this situation seems shady for field use.


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