Sodium Bicarb for treatment of Acidosis?

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RemyMcswain

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Was in a case the other day (Im an intern, so I was basically shadowing a CA-3) and we got an intraop ABG which showed a pH of 7.18. Attending asked for sodium bicarb to correct acidosis.

Its my understanding that when you give bicarb youre basically just dumping CO2 in the patient, and that any increase in pH is secondary to an increase in SID (i.e. increasing strong cation ion sodium, while not increasing strong anion.)
http://www.ncbi.nlm.nih.gov/pubmed/10631227


Do you guys use bicarb to correct metabolic acidosis?

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Was in a case the other day (Im an intern, so I was basically shadowing a CA-3) and we got an intraop ABG which showed a pH of 7.18. Attending asked for sodium bicarb to correct acidosis.

Its my understanding that when you give bicarb youre basically just dumping CO2 in the patient, and that any increase in pH is secondary to an increase in SID (i.e. increasing strong cation ion sodium, while not increasing strong anion.)
http://www.ncbi.nlm.nih.gov/pubmed/10631227


Do you guys use bicarb to correct metabolic acidosis?

you are correct.

in general, i do not use bicarb.

except, when a sudden intolerable decrease in pH is expected (ie release of a clamp or tourniquet), or when all else is failing (ie during a code when i want the pressors to work long enough to gain a foothold - little evidence for this).
 
Agreed. Bicarb is only masking the acidosis and it is better to treat the cause rather than correct the pH. However, if things are beginning to go south in a hurry and you can't correct the problem rapidly enough then bicarb can be a benefit. Mostly by increasing the effectiveness of your inotropes, as Slavin said. Remember, some of the criticism of bicarb came from codes where removal of CO2 was impaired. We don't usually have that issue so some say it won't harm anything to give bicarb. I disagree, CO2 will be trapped intracellularly and therefore, we don't know what the real pH is.

This is a great topic to read up on as an intern. If you grasp it well you will be far ahead of most interns and from what it sounds like even ahead of some of your attendings. Also read about THAM.
 
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ill give it in life threatening acidosis, usually pH<7.0 and when I need my vasopressors to work (usually keep pH above 7.15). our cardiac surgeons want it postop if the pH is below 7.30 :rolleyes: they dont always get it

tham is nice when you cant breathe off the CO2 byproduct, but it isnt cheap, so i usually reserve it for those cases. for the most part, fixing the primary issue (volume depletion, hypoperfusion, pump function, infection) will allow you to fix the pH without bicarb
 
you are correct.

in general, i do not use bicarb.

except, when a sudden intolerable decrease in pH is expected (ie release of a clamp or tourniquet), or when all else is failing (ie during a code when i want the pressors to work long enough to gain a foothold - little evidence for this).

i feel like this is pretty well supported, maybe its just that we all do it. i mean its nice to say "artifical raising of the pH" but truth of the matter is that enzymes just dont work at pH of 7.1 and lower and sometimes you need to help correct that number.
 
HCO3's role in organic acidosis (DKA, Lactic acidosis) is not well founded except for the reasons above ( pH <7.20, pressors not working, etc). The main focus in these sort of problems is to reverse the source/cause of acidosis.

Having said that I frequently give bicarb when there is a non-oragnic component of acidosis such as renal failure, larger volume diarrhea etc. In process such as cardiogenic shock it is not uncommon to start with a pure organic problem and then cause renal failure and resultant inability of the kidney to produce titratable acid and retain bicarb as it should.
 
Its my understanding that when you give bicarb youre basically just dumping CO2 in the patient, and that any increase in pH is secondary to an increase in SID (i.e. increasing strong cation ion sodium, while not increasing strong anion.)
http://www.ncbi.nlm.nih.gov/pubmed/10631227

I didn't read your article, and judging by the previous replies it doesn't look like anyone read it either.

Regardless, is there something wrong with "dumping CO2" on a patient? Assuming they have normal paCO2 and are not hard to ventilate? The CO2 will be gone before you have a chance to draw another blood gas.

Ketafol20: I disagree, CO2 will be trapped intracellularly and therefore, we don't know what the real pH is.

?????
Care to tell us how CO2 is trapped inside cells, considering it diffuses about 40 times faster than O2?
 
I first correct any respiratory acidosis. If pH < 7.2 with a NORMAL pCO2 then I consider administration of bicarb if the patient is hemodynamically unstable with poor response to pressors.

Use caution in any situation where you have increased CO2 production and/or decreased ventilation (e.g. ARDS, uncorrected hypercarbic respiratory failure).

Sodium bicarb to correct metabolic acidosis has not been demonstrated to improve mortality. It is no longer recommended for any ACLS/code situation and has not been for a while. Understand that when you choose to use it, there is oftentimes some wishful thinking involved.

Similar examples of wishful thinking include the use of steroids in refractory hypotension, use of aminocaproic acid in recalcitrant bleeding, use of Factor VIIa in refractory bleeding in a non-hemophiliac, etc. Somewhere out there, someone (maybe even you) has seen it work once so that's why we do it. 90% of the time we cannot see it really working -- but there's always hope it might.....
 
it's good for a 7.5% sodium bolus if you want to give some volume expansion in a small bolus.
 
?????
Care to tell us how CO2 is trapped inside cells, considering it diffuses about 40 times faster than O2?

So are you telling me that you have never heard of paradoxical intracellular acidosis?

Now there is still a lot of controversy regarding the administration of bicarb as we will probably see just in this thread alone.

Paradoxical intracellular acidosis has been described plenty but it has been refuted as well.
 
This issue is one of my pet peeves.

I agree with those posters who have said they reserve it for those times when the pH is<7.2 and catechols aren't working, for hyperkalemic emergencies, for reperfusion/unclamping, and for bicarb-wasting acidoses. Otherwise, fixing the reason for the acidosis should be the focus of therapy.

I love how in some ICUs people get their panties in a wad over a pH of 7.28 and start blasting bicarb in, when in the bed next door they're hyperventilating some poor bastard to a pH of 7.58, which is much worse physiologically, and they don't bat an eye.
 
So are you telling me that you have never heard of paradoxical intracellular acidosis?

Now there is still a lot of controversy regarding the administration of bicarb as we will probably see just in this thread alone.

Paradoxical intracellular acidosis has been described plenty but it has been refuted as well.
There is conflicting evidence on the intracellular effect of bicarb, but part of the theory about why bicarb is ineffective or even harmful is the idea that freely formed CO2 (dissociated from the breakdown of carbonic acid after bicarb infusion) diffuses freely intracellularly, which is where the mitochondria lie and, ultimately is what matters with respect to whole body metabolic function. There is a great article by Gauthier in Critical Care Clinics from 2002 that describes it well.
 
I first correct any respiratory acidosis. If pH < 7.2 with a NORMAL pCO2 then I consider administration of bicarb if the patient is hemodynamically unstable with poor response to pressors.

Use caution in any situation where you have increased CO2 production and/or decreased ventilation (e.g. ARDS, uncorrected hypercarbic respiratory failure).

Sodium bicarb to correct metabolic acidosis has not been demonstrated to improve mortality. It is no longer recommended for any ACLS/code situation and has not been for a while. Understand that when you choose to use it, there is oftentimes some wishful thinking involved.

Similar examples of wishful thinking include the use of steroids in refractory hypotension, use of aminocaproic acid in recalcitrant bleeding, use of Factor VIIa in refractory bleeding in a non-hemophiliac, etc. Somewhere out there, someone (maybe even you) has seen it work once so that's why we do it. 90% of the time we cannot see it really working -- but there's always hope it might.....

Factor VIIa is sweet in big suture line otherwise recalcitrant pedi-cardiac.
 
There is conflicting evidence on the intracellular effect of bicarb, but part of the theory about why bicarb is ineffective or even harmful is the idea that freely formed CO2 (dissociated from the breakdown of carbonic acid after bicarb infusion) diffuses freely intracellularly, which is where the mitochondria lie and, ultimately is what matters with respect to whole body metabolic function. There is a great article by Gauthier in Critical Care Clinics from 2002 that describes it well.

Yes the evidence is very conflicting and currently does not seem to support paradoxical intracellular acidosis. But either way, it is something that every anesthesiologist should be familiar.
 
does anyone know of any articles on using bicarb for ph <7.2?
 
Was in a case the other day (Im an intern, so I was basically shadowing a CA-3) and we got an intraop ABG which showed a pH of 7.18. Attending asked for sodium bicarb to correct acidosis.

Its my understanding that when you give bicarb youre basically just dumping CO2 in the patient, and that any increase in pH is secondary to an increase in SID (i.e. increasing strong cation ion sodium, while not increasing strong anion.)
http://www.ncbi.nlm.nih.gov/pubmed/10631227


Do you guys use bicarb to correct metabolic acidosis?

The Strong Ion Difference equation is complicated - like a 4rth order equation or something like that. Anyway, you are correct that the reason bicarb corrects pH is PROBABLY from the sodium load which is a big part of that equation. Studies that tag the carbon in bicarb show that it is blown away very rapidly. The pH changes have nothing to do with the bicarb part.

I agree with others, THAM all the way.
 
does anyone know of any articles on using bicarb for ph <7.2?

There aren't many, but I found a couple old ones:
Mathieu, D, Neviere, R, Billard, V, et al Effects of bicarbonate therapy on hemodynamics and tissue oxygenation in patients with lactic acidosis: a prospective, controlled clinical study. Crit Care Med 1991;19,1352-1356

Cooper DJ, Walley KR, Wiggs BR, Russell JA.
Ann Intern Med. 1990 Apr 1;112(7):492-8.


This is a nice review of the different buffers and why or why not to use them.
Brian K Gehlbach and Gregory A Schmidt
Bench-to-bedside review: Treating acid&#8211;base abnormalities in the intensive care unit &#8211; the role of buffers
Critical Care 2004, 8:259-265
 
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