Pulse Oximetry Less Accurate in Low SPO2 Ranges for Children

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.