Inaccurate pulse oximetry readings delay COVID-19 therapy for Black patients

Key takeaways:

• Black patients were more likely to have pulse oximetry readings that masked the need for COVID-19 treatment.
• Researchers said clinicians should be mindful of possible pulse oximetry errors in all patients.

Pulse oximeters more frequently overestimated arterial oxygen saturation among Black patients hospitalized with COVID-19 compared with white patients, leading to delayed COVID-19 therapy, a recent study found.

According to Ashraf Fawzy, MD, MPH, an assistant professor of medicine at Johns Hopkins University, and colleagues, evidence suggests that pulse oximeters may systematically overestimate arterial oxygen saturation (SaO₂) in underrepresented populations and increase the risk for occult hypoxemia, “generally defined as a true [SaO₂] below 88% with an oxygen saturation by pulse oximetry (SpO₂) in a normal range above 92%.”

In a previous study, Fawzy and colleagues found that overestimations were linked to a greater likelihood of occult hypoxemia in underrepresented patients who were admitted to hospitals with COVID-19. However, because their study relied on statistical modeling, it remained uncertain whether inaccuracies in oxygen saturation truly led to delayed COVID-19 therapy and if these delays were associated with patients’ race and ethnicity.

To learn more, Fawzy and colleagues conducted a cohort study of 24,504 hospitalized patients with COVID-19 and concurrent SpO₂ and SaO₂ pairings to determine potential links between pulse oximeter errors and likelihood of missed recognition for COVID-19 needs, as well as associations between delayed treatment and odds of readmission, in-hospital mortality and length of stay. The patients were hospitalized between March 2020 and October 2021. Among them, 17% were Black.

The researchers classified a patient as having an unrecognized need for COVID-19 if the first SaO₂ during hospitalization was below 94% despite a 10-minute SpO₂ of 94% or higher.

Compared with white patients, Fawzy and colleagues reported that the adjusted mean difference in overestimation of SaO₂ by pulse oximetry was:

• 0.93 (95% CI, 0.74-1.12) for Black patients;
• 0.49 (95% CI, 0.34-0.63) for Hispanic patients; and
• 0.53 (95% CI, 0.35-0.72) for other patients.

Among 8,635 patients with at least one concurrent SpO₂ and SaO₂ pair and without a need for COVID-19 therapy, Black patients were significantly more likely than white patients to have pulse oximetry measurements that hid an indication for COVID-19 therapy (adjusted OR = 1.65; 95% CI, 1.33-2.03).

Regardless of race and ethnicity, patients with unseen needs for COVID-19 therapy were 10% less likely to receive it (adjusted HR = 0.9; 95% CI, 0.83-0.97) and had higher odds of hospital readmission (aOR = 2.41; 95% CI, 1.39-4.18). There were no significant associations between delayed treatment and length of stay or in-hospital mortality, according to the researchers.

Although pulse oximeter overestimations were highest in underrepresented populations, 13% and 43% of patients who experienced occult hypoxemia and whose needs for COVID-19 therapy were unmet, respectively, were white, the researchers noted.

Although the study focused on underrepresented patient populations diagnosed with COVID-19, the researchers noted that clinicians use pulse oximeters for therapy decisions in several other respiratory illnesses, where there could also be inaccuracies and delays.

“While these factors might play a greater role for patients from minority racial and ethnic groups due to the higher incidence of inaccuracies, clinicians need to be mindful of the potential for pulse oximetry inaccuracies in all patients in which oxygenation affects treatment decisions and clinical outcomes,” the researchers wrote.

They concluded that efforts to improve the accuracy of pulse oximeters are critical because these incorrect estimations “likely extend to other acute respiratory illnesses and oxygen supplementation in chronic respiratory disease, which necessitate ongoing investigation.”