Continuous and reliable measurements of oxygen saturation in critically ill newborn infants using a fiberoptic catheter

Background: Non-invasive oxygen monitoring with pulse oximetry or transcuta neous monitoring has gained widespread use in neonatology. Different factor s like arterial hypotension, peripheral vasoconstriction and edema adversel y affect the accuracy of both methods. To ensure reliable monitoring of oxy gen saturation in critically ill patients we measured oxygen saturation wit h a fiberoptic catheter via umbilical artery. Methods: In ventilated premature infants (FiO(2) > 0.4) a 4F-fiberoptic cat heter (Oximetrix(R))-3, Abbott) was inserted to the descending aorta (Th 6- 8). Simultaneous ly pulse oximetry (SaPO(2)) was performed with the Ohmeda Biox 3700. To compare the reliability of both methods, blood was analysed f or arterial partial oxygen pressure (PaO2), fetal hemoglobin (HbF) and arte rial oxygen saturation (SaO(2)) by complete co-oximetry (Radiometer Copenha gen OSM3) as reference. Results: In 10 premature infants (median gestational age 30.5 weeks; median birth weight 1360 g) oxygen saturation was measured with the fiberoptic ca theter (SaFO(2)) over a total period of 935 hours. In all, 137 blood sample s were analysed for arterial saturation (SaO(2)) by co-oximetry. The mean d ifference between the SaO(2) and SaFO(2) was - 1.89% (+/-1.53); the mean di fference between SaO(2), and the values obtained by pulse oximetry (SaPO(2) ) was -3.09% (+/-2.33). The SaFO(2) results correlated closely with the co- oximetry values (r=0.97; p < 0.0001). Conclusion: In critically ill patients, if non-invasive oxygen monitoring f ails, a fiberoptic catheter offers the possibility of continuous and reliab le measurement of oxygen saturation.