Estimating the P50 for Hemoglobin from a Venous Blood Sample

 

Parameters:

(1) pH of the venous blood sample

(2) PvO2 in mm Hg

 

LOG10(PvO2 in mm Hg if the blood was at pH 7.4) =

= LOG10(PvO2 in mm Hg measured) - (0.5 * (7.4 - (measured pH)))

 

1/k = X =

= (10^(2.7 * LOG10(PvO2 at pH 7.4))) * (100- (PvO2)) / (PvO2)

 

AS REC P50 standard =

= 10^(LOG10(X) / 2.7)

 

where:

• 2.7 is the Hill constant for hemoglobin A.

P50 for the Hemoglobin	Interpretation
< 17 mm Hg	mutant hemoglobin with high oxygen affinity
17 to 35 mm Hg	hemoglobin with normal oxygen affinity
> 35 mm Hg	mutant hemoglobin with low oxygen affinity