Pulse Oxygen Saturation Levels and Arterial Oxygen Tension Values in Newborns Receiving Oxygen Therapy in the Neonatal Intensive Care Unit: Is 85% to 93% an Acceptable Range?

OBJECTIVE. Our aim was to define the relationship of Pao 2 and pulse oxygen saturation values during routine clinical practice and to evaluate whether pulse oxygen saturation values between 85% and 93% were associated with Pao 2 levels of METHODS. Prospective comparison of Pao 2 and pulse oxygen saturation values in 7 NICUs at sea level in 2 countries was performed. The Pao 2 measurements were obtained from indwelling arterial catheters; simultaneous pulse oxygen saturation values were recorded if the pulse oxygen saturation values changed RESULTS. We evaluated 976 paired Pao 2 /pulse oxygen saturation values in 122 neonates. Of the 976 samples, 176 (18%) from infants breathing room air had a mean pulse oxygen saturation of 93.9 ± 4.3% and a median of 95.5%. The analysis of 800 samples from infants breathing supplemental oxygen revealed that, when pulse oxygen saturation values were 85% to 93%, the mean Pao 2 was 56 ± 14.7 mmHg and the median 54 mmHg. At this pulse oxygen saturation level, 86.8% of the samples had Pao 2 values of 40 to 80 mmHg, 8.6% had values of 80 mmHg. When the pulse oxygen saturation values were >93%, the mean Pao 2 was 107.3 ± 59.3 mmHg and the median 91 mmHg. At this pulse oxygen saturation level, 39.5% of the samples had Pao 2 values of 40 to 80 mmHg and 59.5% had values of >80 mmHg. CONCLUSIONS. High Pao 2 occurs very rarely in neonates breathing supplemental oxygen when their pulse oxygen saturation values are 85% to 93%. This pulse oxygen saturation range also is infrequently associated with low Pao 2 values. Pulse oxygen saturation values of >93% are frequently associated with Pao 2 values of >80 mmHg, which may be of risk for some newborns receiving supplemental oxygen.