[thedy]

Hi, it holds that NBB = 41,7 + 0,042 x cHb. What does 41,7 and 0,042 mean? Something physical? Or somekinf of constant? How was derived?
Thanks

[AWK]

Please, do not use an ambiguous abbreviation.  Moreover,
http://www.chemicalforums.com/index.php?topic=65859.0

[Borek]

No idea about details, but in my experience this type of things just combine several physicochemical constants into one, so the meaning and the value has to be traced to the definitions and derivation of the equation.

And as AWK said - please give some more details when asking this type of question, buffer base is not a term used in chemistry and as such is quite ambiguous for us.

[thedy]

I am sorry.By NBB I mean normal buffer base. And this euqation should be Siggaard Andersen equation.

[AWK]

Taken from:
Lars Wiklund (1996) Carbon Dioxide Formation and Elimination in Man, Upsala Journal of Medical Sciences, 101:1, 35-68, DOI: 10.3109/03009739609178913
Article is in public domain.

"The neutralization of hydrogen ions (H+) which is caused by other buffer systems in the serum is not revealed in the determination of standard bicarbonate. Of the anions in the plasma, in practice only HC03- and protein- , form a weak acid with H+ and consequently are able to enter into the buffer system within the pH range in question. This constitutes the "buffer base" (BB) in serum and is normally equivalent to 41.7 mmol/L (17 mmol/L of which is protein). When H+ is neutralized, BB decreases. Thus BB provides a principle of the non-respiratory component in the acid-base balance (18,20,21). However, an appreciable part of the metabolic as well as the respiratory supply of hydrogen ions is buffered by Hb in the red blood cells. The value of BB in whole blood (NBB) thus vanes with the haemoglobin (Hb) value, so that for each g/L of Hb the value increases with 0.042 mmol/L. If NBB for plasma is 41.7, the corresponding value for blood with a Hb concentration of 120 g/L = 41.7 + 120 . 0.042 = 46.7 mmol/L"

[thedy]

Taken from:
Lars Wiklund (1996) Carbon Dioxide Formation and Elimination in Man, Upsala Journal of Medical Sciences, 101:1, 35-68, DOI: 10.3109/03009739609178913
Article is in public domain.

"The neutralization of hydrogen ions (H+) which is caused by other buffer systems in the serum is not revealed in the determination of standard bicarbonate. Of the anions in the plasma, in practice only HC03- and protein- , form a weak acid with H+ and consequently are able to enter into the buffer system within the pH range in question. This constitutes the "buffer base" (BB) in serum and is normally equivalent to 41.7 mmol/L (17 mmol/L of which is protein). When H+ is neutralized, BB decreases. Thus BB provides a principle of the non-respiratory component in the acid-base balance (18,20,21). However, an appreciable part of the metabolic as well as the respiratory supply of hydrogen ions is buffered by Hb in the red blood cells. The value of BB in whole blood (NBB) thus vanes with the haemoglobin (Hb) value, so that for each g/L of Hb the value increases with 0.042 mmol/L. If NBB for plasma is 41.7, the corresponding value for blood with a Hb concentration of 120 g/L = 41.7 + 120 . 0.042 = 46.7 mmol/L"

thank you How did you find it?

[AWK]

Google: NBB = 41.7 + 0.042 x Hb Siggaard Andersen
note comma replaced by dot and c omitted