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bluestar
Forum Guru Topics: 236 Posts: 724 
I totally can't understand this entry of P. 278 of FA. First it gives a winter's formula which I never saw before: Pco2 = 1.5 (Hco3) + 8 +/ 2 then the 4 combination of acidosis and alkalosis seem to align wrong. but I'll just put them here in the way FA put it: :arrow: metabolic acidosis: Pco2 increases 0.7 mmHg for every increase of 10 mmHg Pco2 :arrow: metabolic alkalosis: :arrow: rspiratory acidosis: acute  increase 1 mEq/L Hco3 for every increase of 10 mmHg Pco2; chronic  increase 3.5 mEq/L Hco3 for every increase of 10 mmHg Pco2 :arrow: rspiratory alkalosis: acute  decrease 2 mEq/L Hco3 for every decrease of 10 mmHg Pco2; chronic  decrease 5 mEq/L Hco3 for every decrease of 10 mmHg Pco2 What does the Winter's formula mean? And how did they get those conclusions, can anybody explain for me?  
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mash
Forum Guru Topics: 147 Posts: 1299 
hey bluestar check this out http://www.fpnotebook.com/REN54.htm  
bluestar
Forum Guru Topics: 236 Posts: 724 
thank you mash for the website. Now I know these are different formulas we can apply to diff conditions. But do you think we need to memorize them all? without these formulas, we can still judge what kind of acidbase abnormality there is, even though not so accurately shown in figures.  
mash
Forum Guru Topics: 147 Posts: 1299 
of course we can judge frm figures and dat is wat they test on usmle (this is wat i think ) coz i vent come across any ques where these formulae r reqd..... wat do u say?  
Idiopathic
Forum Guru Topics: 19 Posts: 639 
Any HCO3 under 15, you know you have a primary metabolic acidosis (possibly mixed also) Any CO2 over 45, you know you have a primary respiratory acidosis (possibly mixed also) I do not think you have to know the formulas, the clinical picture should mark the situation very clearly.  
bluestar
Forum Guru Topics: 236 Posts: 724 
I agree with you both. btw, idiopathic, where does the figure 15 and 45 come from?  
Idiopathic
Forum Guru Topics: 19 Posts: 639 
Just a standard that we were told by a clinician. He said it is a certainty.  
Sakaki
Forum Senior Topics: 1 Posts: 238 
Those are the bedside rules for assessment of acidbase compensation, and from what I remember, they are empirical. And Winter's formula is just as it says: the 1.5 + 8 rule. Basically, as mentioned above, we compare the actual values obtained from the lab with the expected values in order to assess the nature of the compensation in the disorder. I really doubt the utility of these rules. I can explain them, but I'm pretty sure that you don't need to know them anyways.  
bluestar
Forum Guru Topics: 236 Posts: 724 
thank you all very much! :P  
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