i got the following scenario:

blood pH: 7.23
bicarbonate: 16
Pco2: 40 mmHG
Po2: 88 mmHG;

which is the most likely diagnostic?
a.metabolic acidosis
b.respiratory acidosis
c.mixed respiratory and metabolic acidosis
d.mixed metabolic acidosis and respiratory alkalosis
e.normal

my first impresion: acidic pH with low bicarbonate makes metabolic acidosis; normal Pco2 makes NO respiratory compensation....i choose answer a.; on explinations they said is c. why? because co2 should be 32 mmHG(after Winter formula); well...here is my question: if we are taking this explination as granted, then ALL the acid base disturbances should have compensation and my concern is how will look the noncompensated acid base disturbances???? that means we should not choose that answer where says 'compansation'; if anybody can give me a real and strong explanation, i will really apreciate it....thanks!

Hi friend,
I have an answer. Respiratory compensation in response to metabolic acidosis can he quantified with
Winter's formula:
Pc:o2= 1.5X(HCO3) + 8+/-2
Pco2 increase .7mmHg for every 1 mEq/L bicarbonate increase.
In this case, Pco2 should be in range of 30 and 34mmHg. 40mmHg is normal Pco2 in individual but in acidosis, it should decrease if there is respiratory compensation. So the answer is
mixed respiratory and metabolic acidosis.

fantastic explanation and thank you for that....very similar to what offer uworld....still i got 1 more question: we ALWAYS have to see which is the respiratory compensation based on Winter formula....how it will look this scenario if we don't have respiratory compansation???? how i am supose to know WHEN we have and IF we have compensation???? you said in your comment that Pco2 should be 30 to 34 IF WE HAVE COMPENSATION!!!!
my frustation is not with the explanation which i agree with it....my opinion: both answers are good...why? if you have compensation, Pco2 should be arround 32(jusy like you explain) but we don't have that; so we remain with 2 options: pure metabolic acidosis WITHOUT compensation or mixed metabolic and respiratory acidosis; if we don't have compensation, Pco2 should be normal and in the question is 40 mmHG=> answer a. is a good choice+based on this logic, it's a pure metabolic acidosis without compensation; second option is with combined acidosis and based on this answer c. is a good option also; but which one is 'the best one' and why is that???again...my frustation is coming from the question posible answers not from your explanation/their explanation regarding winter's formula.

hi,
Normally metabolic acidosis is compensated unless there is any respiratory problem. Uncompensated means there is some sort of respiratory problem. So uncompensated metabolic acidosis is not in my choice.
qingquan

first of all i wanna thank you again for your response. this is my last post regarding this topic. before i'm done, just for the hack of it, i will let you know that this pacient has been diagnose with a chronic pulmonary disease and in the last 3 days he had a mild productive cough and because of this acute situation he is presenting to the doctor....so, like you said, uncompensated metabolic acidosis might go with a respiratory problem; that's all what i have to say. take care now.