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?

Abstract

OBJECTIVE. Our aim was to define the relationship of Pao2 and pulse oxygen saturation values during routine clinical practice and to evaluate whether pulse oxygen saturation values between 85% and 93% were associated with Pao2 levels of <40 mmHg. METHODS. Prospective comparison of Pao2 and pulse oxygen saturation values in 7 NICUs at sea level in 2 countries was performed. The Pao2 measurements were obtained from indwelling arterial catheters; simultaneous pulse oxygen saturation values were recorded if the pulse oxygen saturation values changed <1% before, during, and after the arterial gas sample was obtained. RESULTS. We evaluated 976 paired Pao2/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 Pao2 was 56 ± 14.7 mmHg and the median 54 mmHg. At this pulse oxygen saturation level, 86.8% of the samples had Pao2 values of 40 to 80 mmHg, 8.6% had values of <40 mmHg, and 4.6% had values of >80 mmHg. When the pulse oxygen saturation values were >93%, the mean Pao2 was 107.3 ± 59.3 mmHg and the median 91 mmHg. At this pulse oxygen saturation level, 39.5% of the samples had Pao2 values of 40 to 80 mmHg and 59.5% had values of >80 mmHg. CONCLUSIONS. High Pao2 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 Pao2 values. Pulse oxygen saturation values of >93% are frequently associated with Pao2 values of >80 mmHg, which may be of risk for some newborns receiving supplemental oxygen.