Effects of fetal hemoglobin on accurate measurements of oxygen saturation in neonates.

PURPOSE

To examine the accuracy of oxygen saturation (So(2)) in relation to blood oxyhemoglobin (Hbo(2)) measurements with the effects of fetal hemoglobin (HbF) determined and their oxyhemoglobin dissociation curves.

METHOD

Twenty neonates with gestational ages ranging from 25 to 34 weeks, who had umbilical arterial or venous lines inserted, were investigated. Analyses were performed with 169 arterial and 41 venous blood samples from these infants by employing HbF- and HbA-mode (as controls) blood analyses, using a hemoximeter.

RESULTS

Without adjusting the effects of HbF when using HbA-mode analyses, mean So(2) measurements were elevated for 5% (+/-1.38) compared with the results of HbF-mode analyses, with 3.5% elevated HbCO levels for the total blood samples. With left-shifted oxyhemoglobin dissociation curves in neonates, for the critical values of oxygen tension values between 50 and 75 mm Hg, arterial Hbo(2) ranged from 94% to 96%, Sao(2) from 97% to 98%, and Spo(2) from 96% to 97% (compared to 85%-94% in healthy adults).

CONCLUSIONS

The left-shifted oxyhemoglobin curves warrant the importance of accurate measurements of oxygenation status for neonates. Fetal hemoglobin determination is essential for accurate So(2) measurements and the assessment of proper oxygenation status in neonates.