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Accuracy of Pulse Oximetry and Risk Factors Associated With Discrepancy From Arterial Oxygenation in Asian Patients
Toshishige Takagi1, Tomoko Fujii1, Sae Nakamura1
1Department of Intensive Care, Jikei University Hospital, Tokyo, Japan.
Background:
Oxygen administration is often guided by pulse oximeter readings. However, inaccuracies have been reported, particularly in patients with darker skin tones. During the COVID-19 pandemic, racial and ethnic disparities in hypoxemia detection emerged, with studies showing a higher incidence of hidden hypoxemia in Black and Hispanic patients. However, limited data exist regarding the Asian population.
Research Question:
How accurate are oxygen saturation (Spo2) readings in Asian patients with critical illness, and what factors contribute to discrepancies with arterial oxygen saturation (Sao2)?
Study Design And Methods:
We conducted a single-center observational study in an ICU at a tertiary care hospital in Japan, including all adult patients admitted from October 2013 through September 2021. We collected data from electronic records and analyzed for agreement between Spo2 and Sao2 using modified Bland-Altman plots. We performed multivariable regression analysis to identify factors associated with Spo2-Sao2 differences. We used cubic splines to model associations between the differences and mortality. To further explore potential mechanisms of dissociation, subgroups of patients with chronic dialysis and sepsis were analyzed.
Results:
Clinical data from 10,698 patients admitted to the ICU were analyzed. The mean bias between Spo2 and Sao2 was -1.2%, with the largest discrepancies occurring 24.7 hours after ICU admission. Hidden hypoxemia (Sao2 < 88%, Spo2 ≥ 88%) occurred in 0.8% of patients, and serious hidden hypoxemia (Spo2 ≥ 92%) occurred in 0.6% of patients. Overestimation of Sao2 was associated with high creatinine levels, particularly among patients with chronic hemodialysis, whereas underestimation was associated with sepsis, mechanical ventilation, and signs of impaired systemic perfusion. We observed a U-shaped relation between the Spo2 and Sao2 differences and mortality, indicating a nonlinear association.
Interpretation:
Our results show that dissociation between Spo2 and Sao2 in Asian patients in the ICU was small; however, overestimation and underestimation were associated with increased mortality risk, particularly among patients with chronic hemodialysis or impaired peripheral perfusion.
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