Fetal .respiratory gas equilibria are more complicated than in the case of adult blood because the fetus has several hemoglobins,´. HbF and HbA, change with gastational age. Despite the great clinically importance of this area, oxygen binding properties of fetal blood currently are known only at one point on the curves i, e, the affinity at halfsaturation, pso. Continnous dygnamic isocapneic oxygen equilibrium curve (O2EC) was measured on fetal cord blood sample.
O2EC was generated by a recently developed dual wavelength (430-453nm) spectrophotometry and electrode oximetry on thin blood films technique for measuring the complete dynamic ligand equilibrium curve from zero to complete saturation.
Affinities and interaction coefficients were determined at all saturations. The gool of this work was to synthesize the results of this measurements into useful practical
modified Hill´s equation describing oxggen equilibrium curve in normal fetal blood.
Results are summarized as follows:
1. HbF content of cord blood was 66.2±1.35% of total Hb by isoelectric focussing.
2. 2. 3-DPG content of cord blood was 5.31 nM/ml of RBC
3. O2EC of normal fetal blood under standard condition (pH=7.4, Pco2=40mmHg and 37°C) was obtained and pso was 22. 38±0. 026 mmHg.
4. CO2 Bohr coefficient(Alog pso/ApH) was -0. 433±0.025 and fixed acid Bohr coefficient (Alog pso/APH, OH+) was -0.208.
5. Hill´s constant "n" was 2.714±0.012 and constant K was 2.19x10-4.
6. Empiric modification of Hill´s equation may be used to compute po2(mmHg) from saturation (s) for 0.05?´O.95 in normal fetal blood under standard conditions was as Follow: po2(s) = (s/2.19 x 10-`(1?s))12´714?C(2.55(s?O.195))2) 2.63+0.06
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