Low pO2 Contributes to Potential Error in Oxygen Saturation Calculations Using a Point-of-Care Assay

Ian L. Gunsolus, Sara A. Love, Louis P. Kohl, Martin Schmidt, Fred S. Apple

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Objectives: The present study addressed the accuracy of calculated oxygen saturation (sO2) using point-of-care (POC) testing compared with measured values on a blood gas analyzer. Methods: In total, 3,323 sO2 values were measured in 1,180 patients using a CO-oximeter (ABL 800 Flex; Radiometer, Copenhagen, Denmark). Measured parameters were then used to calculate an expected sO2 for the POC method (Abbott i-STAT; Abbott POC, Princeton, NJ). Cases in which calculated sO2 differed from measured sO2 by 10% or more were analyzed. Results: Of the 3,323 comparisons performed, 260 (8%) showed discrepancies (± ≥10%) between measured and calculated sO2 values. Ninety-four of discrepant measurements (245 of 260) occurred when pO2 was less than 50 mm Hg. pH and bicarbonate distributions shifted to lower values in discrepant vs nondiscrepant cases. Conclusions: Our results suggest that the likelihood of discrepant sO2 is 27% among patients with pO2 less than 50 mm Hg. Direct measurement of sO2 by CO-oximetry is strongly suggested in this clinical scenario.

Original languageEnglish (US)
Pages (from-to)82-86
Number of pages5
JournalAmerican journal of clinical pathology
Volume149
Issue number1
DOIs
StatePublished - Jan 1 2018

Keywords

  • ISTAT
  • Oxygen saturation
  • Point-of-care testing

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