The cord blood oxygen affinity from normal human newborns: 1) A methodological approach

A correct analysis of O2 affinity in neonatal whole blood puts some important, still unsolved problems of methodology, mainly based upon the fact that this kind of blood is a mixture of at least two major hemoglobins, i.e. 2/3 Hb-F and 1/3 Hb-A, having different affinities. Whereas adult blood mainly contains Hb-A. Within such a perspective, the Authors have checked if the empirical Davenport's nomogram, correcting the pO2s of adult blood to the same standard pH of 7.4, can also be used for neonatal blood. The answer is affirmative, and in addition the nomogram can also be replaced, with some advantage, by an only mathematical correction of the measured pO2s, in which pH differences from 7.4 (either positive or negative) are converted in proportional differences of pO2 and either added or subtracted to the values of these latter. Hb-CO level is undoubtedly higher in newborns than in non-smoker adults, but no factor for T50 calculation of neonatal blood has been till now identified. The Authors have determined a factor of -0.36, which can be obtained from the homologous (experimental) "adult" factor of -0.27, by multiplying this latter for 1.35.