Discordance Between Invasive and NonInvasive Oxygen Saturation in Critically Ill COVID-19 Patients.

Area of Science:

• Critical Care Medicine
• Pulmonary Medicine
• Infectious Diseases

Background:

• Accurate monitoring of oxygenation is crucial for critically ill patients.
• Pulse oximetry (SpO2) and arterial blood gas (ABG) analysis (SaO2) are standard methods for measuring oxygen saturation.
• Discordance between SpO2 and SaO2 can impact clinical decision-making.

Purpose of the Study:

• To compare the rate of discordance between SpO2 and SaO2 in critically ill patients with and without COVID-19.
• To investigate if SpO2 readings could misclassify the severity of hypoxemia in COVID-19 patients.
• To identify factors confounding the observed discordance.

Main Methods:

• Retrospective analysis of paired SpO2 and SaO2 readings from adult ICU admissions (March-May 2020).
• Primary outcome: rate of discordance (|SaO2-SpO2|>4%) in COVID-19(+) vs. COVID-19(-) patients.
• Multivariate regression assessed confounding by pH, temperature, renal replacement therapy, and race.

Main Results:

• Higher saturation discordance observed in COVID-19(+) patients (27.9%) compared to COVID-19(-) patients (16.7%).
• COVID-19(+) patients had increased odds of SpO2 misclassifying their oxygenation status.
• The association between COVID-19 status and discordance was lost after controlling for self-identified race.

Conclusions:

• Pulse oximetry showed greater discordance with ABG in critically ill COVID-19 patients.
• Racial differences between the studied cohorts appear to be the primary driver of this observed discordance.
• Further research is needed to understand and address racial disparities in SpO2 accuracy.