Pulse oximetry may sometimes be inaccurate in hypoxemic children

Pulse oximetry is ubiquitous in anesthesia and critical care but decisions may be made on erroneous data.

Pulse oximeters take advantage of the differing absorption of red and infrared light by oxygenated and deoxygenated hemoglobin to produce a signal. A proprietary algorithm specific to each manufacturer is used to convert absorption to a value for oxygen saturation.

These algorithms have all been developed by asking healthy adult volunteers to breathe various gas mixtures, including hypoxic blends that result in lower oximeter saturation readings. No similar experiments have been performed with children, yet pediatricians routinely use oximetry results to make decisions regarding need for intubation, oxygen support, timing of surgery in congenital heart disease, etc. It is often stated that pulse oximetry overestimates arterial saturations during hypoxemia. Multiple investigators have demonstrated this, however they have also demonstrated very wide confidence intervals in these measurements. In turn, pulse oximeter saturations less than possibly 90% may be inaccurate as well as imprecise.

In the absence of improved technology we must rely on these data. However, these is an appropriate population of subjects that could be used to generate algorithms for hypoxic children. Children undergoing congenital heart surgery could supply the needed data. We should consider coaxing manufacturers to undertake this research and improve the accuracy and precision of their devices.

References

Ross PA, Newth CJL, Khemani RG. Accuracy of pulse oximetry in children. Pediatrics. January 2014.

Griksaitis MJ, Scrimgeour GE, Pappachan JV, Baldock AJ. Accuracy of the Masimo SET LNCS neo peripheral pulse oximeter in cyanotic congenital heart disease. Cardiology in the Young. October 2015.