Don't hold PAT: watch for and correct oximetry artifact

Abstract

This study evaluated the accuracy of the algorithmic oxygen saturation (SpO₂) nadir detection of WatchPAT (Zoll/Itamar, Caesarea, Israel) compared with visual inspection in a real-world setting. SpO₂ tracings for 209 consecutive adult WatchPAT recordings were reviewed for SpO₂ artifact, with erroneous SpO₂ data removed manually. Error rates for SpO₂ minima were determined across all studies, and relationships between correct and erroneous studies examined. The overall error rate for SpO₂ nadir was 22.5%. Erroneous studies had overall less time spent at SpO₂ ≤ 88%, higher true SpO₂ nadir, lower mean body mass index, and greater artifact time; however, these variables were not associated with the magnitude of discrepancy between manual and algorithmically derived SpO₂ minima. These data demonstrate that SpO₂ nadir determined by WatchPAT algorithms should not be considered universally accurate. Like other home sleep apnea tests, visual inspection and manual correction of the study data are often required to derive accurate clinical results.

Citation: Plante DT, Rumble ME. Don't hold PAT: watch for and correct oximetry artifact. J Clin Sleep Med. 2023;19(12):2113-2116.

Keywords: WatchPAT; hypoxemia; sleep apnea; tonometry.

Figure 1. Erroneous SpO₂ minima detected by WatchPAT.

(A) Individual differences between erroneous and corrected SpO₂ nadirs across all individual participants (n = 47). Participant denoted by blue asterisks is shown in detail in parts B and C as an example. (B) 100-s SpO₂ tracing derived from the native WatchPAT algorithm. Note failure of the algorithm to fully exclude artifactual data, which resulted in a reported SpO₂ nadir of 73%. (C) Manual expansion of the excluded artifactual segment (denoted by the white text box) after visual inspection resulted in a change in SpO₂ nadir from 73% to 87% for the study. SpO₂ = oxygen saturation.