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Tweetorial: An amp of 8.4% NaBicarb in the ICU 
. Panacea or poison?
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Normally, at a pH of 7.4, what is the concentration of H+ in the arterial plasma?
. Panacea or poison? #NephTwitter #askrenal #medtwitter @askrenal
Normally, at a pH of 7.4, what is the concentration of H+ in the arterial plasma?
Let’s begin with a mind excercise 
!
How efficient is Bicarbonate as a buffer?
Remember:
[H+] = 24 x PCO2/[HCO3-]
pCO2 = 40
[HCO3-] = 24
Hence, normally:
[H+] = 24 x 40/24 = 40 nanoeq/L
If [H+] exceeds 160 nanoeq/L
pH = 6.8 DEATH 
! How efficient is Bicarbonate as a buffer?
Remember:
[H+] = 24 x PCO2/[HCO3-]
pCO2 = 40
[HCO3-] = 24
Hence, normally:
[H+] = 24 x 40/24 = 40 nanoeq/L
If [H+] exceeds 160 nanoeq/L
pH = 6.8 DEATH
Say a healthy individual presents after attempting suicide 
by ingesting an acidic substance 
, adding 12 MILLION nanoeQ/L (12 meQ/L) of H+ to circulating plasma (300,000 times normal [H+])- what pH do you expect at presentation, assuming NO respiratory compensation?
by ingesting an acidic substance , adding 12 MILLION nanoeQ/L (12 meQ/L) of H+ to circulating plasma (300,000 times normal [H+])- what pH do you expect at presentation, assuming NO respiratory compensation?
Adding 12 MILLION nanoeq/L (12 meq/L) of H+ to the circulating plasma 
will result in the consumption of 12 meQ/L of HCO3 to buffer the 12meQ/L of H+Now [H+] = 24 x 40/12 = 80 nanoeq/L
pH = 7.1Hence, increasing [H+] by 300,000x only moderately decreases pH!
WOW!
That speaks to the remarkable efficacy of bicarbonate in buffering acid and improving acidemia! 
Should we give acidemic pts in ICU IV NaHCO3?
In an 84 kg male, administering 1 amp (50 meQ) of NaHCO3 will increase serum bicarbonate concentration by:
Should we give acidemic pts in ICU IV NaHCO3
?In an 84 kg male, administering 1 amp (50 meQ) of NaHCO3 will increase serum bicarbonate concentration by:
Nl serum [HCO3]-: 24 meq/L
1 amp 8.4% NaHCO3 injection has 50 meq bicarbonate
Administered IV NaHCO3 distributes in total body water
(TBW=60% body weight)
1 amp 8.4% NaHCO3 injection
has 50 meq bicarbonateAdministered IV NaHCO3 distributes in total body water
(TBW=60% body weight)
Let’s go through a typical ICU case:
84 kg male TBW = 50L
Severe ARDS, on LTV ventilation
Shock, on multiple pressors
Serum Bicarb = 10 ; pCO2 = 35
[H+] = 24 x 35/10 = 84 nanoeq/L pH = 7.10
84 kg male
TBW = 50LSevere ARDS, on LTV ventilation
Shock, on multiple pressors
Serum Bicarb = 10 ; pCO2 = 35
[H+] = 24 x 35/10 = 84 nanoeq/L
pH = 7.10
Let’s administer 1 amp (50meQ) of NaHCO3
TBW= 84kg x 0.6 = 50L
50meq bicarb distributed over 50L will increase serum bicarb by 1meQ/L
Serum bicarb will increase from 10Meq/L to 11meq/L
[H+] = 24 x 35/11= 76.3 nanoeq/L pH = 7.11
pH increased by 0.01
TBW= 84kg x 0.6 = 50L
50meq bicarb
distributed over 50L will increase serum bicarb by 1meQ/L Serum bicarb will increase from 10Meq/L to 11meq/L
[H+] = 24 x 35/11= 76.3 nanoeq/L
pH = 7.11pH increased by 0.01
Well that’s rather dissatisfying 
But...
Clinically, when I administer an amp of NaHCO3 it works!
I have see an amp of bicarb instantly improve hemodynamics... probably because it improves acidosis...win win...
. Agree?
But...
Clinically, when I administer an amp of NaHCO3 it works!
I have see an amp of bicarb instantly improve hemodynamics... probably because it improves acidosis...win win...
. Agree?
Let’s do another mind excercise!
How much Na is in an amp of NaHCO3?
50 ml amp of 8.4% NaBicarb is profoundly concentrated —> 2000 mosm/L = thats 2x hypertonic saline
1 meQ of Na = 23 mg of Na
50meQ of Na = 1150 mg Na
That’s how much Na is in 1/2 teaspoon of salt!
How much Na is in an amp of NaHCO3?
50 ml amp of 8.4% NaBicarb is profoundly concentrated —> 2000 mosm/L = thats 2x hypertonic saline
1 meQ of Na = 23 mg of Na
50meQ of Na = 1150 mg Na
That’s how much Na is in 1/2 teaspoon of salt!
So... don’t be fooled! 
The amp of NaBicarb instantly, BUT transiently, improves BP NOT due to improvement in acidemia...
... but rather due to the injection of 1/2 teaspoon of salt into the patients IV 
Now lend thought to those soaked ARDS inflicted lungs
The amp of NaBicarb instantly, BUT transiently, improves BP NOT due to improvement in acidemia...
... but rather due to the injection of 1/2 teaspoon of salt
into the patients IV Now lend thought to those soaked ARDS inflicted lungs
Note, we are assuming:
http://1.No ongoing acid production
2.Constant pCO2
In reality, minor increments in Bicarb/pH via injection are defeated by ongoing acid production
Naload leads to uninvited volume retention worse ARDS pCO2 retention worse acidemia
http://1.No ongoing acid production
2.Constant pCO2
In reality, minor increments in Bicarb/pH via injection are defeated by ongoing acid production
Na
load leads to uninvited volume retention worse ARDS pCO2 retention worse acidemia
In summary, with an amp of bicarb:
The improvement in pH is negligible and likely quickly negated by ongoing acid production (continued shock/ARDS)
We have subjected an ARDS patient to a load of Nawhich may lead to stiffer lungs
In this patient, harm>>benefit
:The improvement in pH is negligible and likely quickly negated by ongoing acid production (continued shock/ARDS)We have subjected an ARDS patient to a load of Nawhich may lead to stiffer lungsIn this patient, harm>>benefit
What if we use an isotonic bicarbonate drip?
Suppose we administer an isotonic NaHCO3 gtt with 3 amps bicarb (150 meq) in 1 L D5W
@ 100cc/hr
150meQ/50L=3meQ/L
Serum bicarb: 10Meq/L 13meQ/L
[H+] = 24 x 35/13= 64 nanoeq/L pH = 7.2
We have increased pH by 0.1 in 10 hrs
Suppose we administer an isotonic NaHCO3 gtt with 3 amps bicarb (150 meq) in 1 L D5W
@ 100cc/hr150meQ/50L=3meQ/L
Serum bicarb: 10Meq/L
13meQ/L[H+] = 24 x 35/13= 64 nanoeq/L
pH = 7.2We have increased pH by 0.1 in 10 hrs
Key points 
:
An amp of NaBicarb contains 50meQ bicarbonate that distributes in TBW
An amp of Nabicarb contains 1150 mg of Na
An isotonic drip of Nabicarb has 150meQ of bicarbonate that distributes in TBW
This drip contains 3450 mg of sodium equal to 1.5 tsp salt
:An amp of NaBicarb contains 50meQ bicarbonate that distributes in TBWAn amp of Nabicarb contains 1150 mg of NaAn isotonic drip of Nabicarb has 150meQ of bicarbonate that distributes in TBWThis drip contains 3450 mg of sodium equal to 1.5 tsp salt
Key points :
Na load is what causes instant improvement in BP when an amp of Nabicarb is administered
Na load may prove harmful in overloaded pts
Weigh risks/benefits when administering bicarb in volume overloaded pts w acidemia
Treat underlying etiology of acidosis
:Na load is what causes instant improvement in BP when an amp of Nabicarb is administeredNa load may prove harmful in overloaded ptsWeigh risks/benefits when administering bicarb in volume overloaded pts w acidemia Treat underlying etiology of acidosis
Most benifit from an amp of Bicarb can be derived once ongoing acid production has decreasedVolume depleted patients will not suffer the harm of a Na loadMeasuring serum Bicarbonate within 2 hrs of administration may be misleading as it has not yet distributed in TBW.
An amp of NaBicarb has the following amounts of Na(mg) and Bicarb(meQ), respectively:
No drug is a panacea (except fish oil?) 
Every drug can be a poison
Every drug can be a poison
