Inaccuracy of pulse oximeter readings could impact care of Black patients with HF
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Key takeaways:
- Pulse oximeter readings are often less accurate in Black patients compared with white patients.
- Inaccurate pulse oximeter readings may lead to denial of needed therapies to Black patients with heart failure.
Inaccuracy of pulse oximeter readings in Black patients could mean that those with HF may have the severity of their disease underestimated and not receive appropriate care, researchers reported.
As Healio previously reported, in 2022, an FDA panel concluded that pulse oximeters do not perform as well in patients with darker skin pigmentation as they do in those with lighter pigmentation. On Feb. 2, the panel reviewed and generally accepted proposed changes to premarket assessment of pulse oximeter performance.
“After a publication showing that Black patients were at risk for unidentified low oxygen saturation when using a pulse oximeter instead of measuring oxygen directly from the blood, we worried that this discrepancy could impact Black patients with heart failure since we use the oxygen saturation to calculate important hemodynamic parameters,” Sarah K. Adie, PharmD, BCCP, clinical pharmacy specialist in cardiology at University of Michigan Health and adjunct clinical assistant professor in the University of Michigan College of Pharmacy, told Healio. “These hemodynamic parameters are used to guide management decisions including candidacy for heart pumps or heart transplants.”
Adie and colleagues wrote in Circulation: Cardiovascular Quality and Outcomes that peripheral oxygen saturation (SpO2) has been reported to be inaccurately measured by pulse oximeters in Black patients compared with arterial oxygen saturation (SaO2), and SpO2 is sometimes used instead of SaO2 in the Fick equation to calculate cardiac output in patients with HF.
Inaccuracies in measurements
The researchers analyzed 204 Black or white patients (mean age, 65 years; 39% women; 22% Black) admitted to an ICU in the Michigan Medicine system who required pulmonary artery catheterization from January 2016 to August 2022. Using an estimated oxygen consumption, the researchers calculated for all patients Fick cardiac output, cardiac index, systemic vascular resistances and pulmonary vascular resistances by both SpO2 and SaO2.
After adjustment for covariates, median SpO2 was higher than median SaO2 by 6% in Black patients (P < .001) but by only 1% in white patients (P = .074), according to the researchers.
“The higher melanin content in darker skin tones can interfere with absorption of light that is used to measure the amount of oxygenated blood using pulse oximeters,” Adie told Healio.
The Fick cardiac output calculations using SpO2 and those using SaO2 were equal to within 1 decimal point in 88.1% of white patients but in only one Black patient (2.2%; P < .001), Adie and colleagues wrote.
The average absolute difference in Fick cardiac output calculations using SpO2 and those using SaO2 was 0.93 in Black patients but 0.05 in white patients (P < .001), according to the researchers. In patients with low cardiac output, the average absolute difference was 0.46 in Black patients and 0.02 in white patients (P < .001).
Compared with white patients, for Black patients, the average difference in cardiac output was lower when using SpO2 instead of SaO2 (weighted linear regression slope, –0.9; 95% CI, –1.37 to –0.43; P < .001), the researchers wrote, noting that there were also differences in cardiac index, systemic vascular resistances and pulmonary vascular resistances. In particular, overestimation of pulmonary vascular resistances could lead to denial of appropriate therapies for advanced HF such as transplantation, they wrote.
‘Move closer toward equity’
“Inaccuracies in hemodynamic measurements could lead to the use of medications that, while intended to be helpful, could result in harm,” Scott W. Ketcham, MD, fellow in cardiovascular medicine at University of Michigan Health, told Healio. “More importantly, these inaccuracies could preclude Black patients with heart failure from receiving potentially lifesaving therapies such as heart transplantation.
“We need to be more vigilant about the use of pulse oximetry in not just Black patients with heart failure, but in all patients with darker skin tones,” Ketcham told Healio. “That being said, in Black patients with heart failure, we should use alternative methods of measuring oxygen content in the blood or alternative methods of measuring hemodynamics in order to move closer toward equity in care.”
For more information:
Sarah K. Adie, PharmD, BCCP, can be reached at adies@med.umich.edu.
Scott W. Ketcham, MD, can be reached at ketchams@med.umich.edu.
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