The accuracy of pulse oximetry varies significantly in low saturation ranges when analyzing children, according to a new study from researchers at Children’s Hospital Los Angeles and University of Southern California Keck School of Medicine.

For the study, researchers evaluated 225 mechanically ventilated children from five pediatric ICUs with a SpO2 ?97%. Researchers simultaneously obtained an arterial blood gas sample, SpO2 from pulse oximetry and arterial oxygen saturations from CO-oximetry (SaO2).

According to the results, a total of 66% of the samples had a positive bias (SpO2 – SaO2 > 0). The entire range of SpO2 65% to 97% had a mean bias of 3.3% and a median bias of 2%.

The bias was greatest in the SpO2 range 81% to 85% (336 samples, median 6%, mean 6.6%). However, in higher oxygen saturation levels (91% to 97%), the bias was limited (901 samples, median 1%, mean 1.5%).

“This study identified that the accuracy of pulse oximetry varies significantly as a function of the SpO2 range. Saturations measured by pulse oximetry on average overestimate SaO2 from CO-oximetry in the SpO2 range of 76% to 90%,” the authors wrote.

“Better pulse oximetry algorithms are needed for accurate assessment of children with saturations in the hypoxemic range,” the authors concluded.