Pulse Oximetry and Race in Critically Ill Adults

OBJECTIVES: For critically ill adults, oxygen saturation is continuously monitored using pulse oximetry (Spo(2)) as a surrogate for arterial oxygen saturation (Sao(2)). Skin pigmentation may affect accuracy of Spo(2) by introducing error from statistical bias, variance, or both. We evaluated relationships between race, Spo(2), Sao(2), and hypoxemia (Sao(2) < 88%) or hyperoxemia (Pao(2) > 150 mm Hg) among adults receiving mechanical ventilation in a medical ICU. DESIGN: Single-center, observational study. SETTING: Medical ICU at an academic medical center. PATIENTS: Critically ill adults receiving mechanical ventilation from July 2018 to February 2021, excluding patients with COVID-19, with race documented as Black or White in the electronic medical record, who had a pair of Spo(2) and Sao(2) measurements collected within 10 minutes of each other. INTERVENTIONS: None. MEASUREMENTS: We included 1,024 patients with 5,557 paired measurements within 10 minutes, of which 3,885 (70%) were within 1 minute. Of all pairs, 769 (14%) were from Black patients and 4,788 (86%) were from White patients. In analyses using a mixed-effects model, we found that across the range of Spo(2) values of 92-98%, the associated Sao(2) value was approximately 1% point lower for Black patients compared with White patients. Among patients with a Spo(2) value between 92% and 96%, Black patients were more likely to have both hypoxemia (3.5% vs 1.1%; p = 0.002) and hyperoxemia (4.7% vs 2.4%; p = 0.03), compared with White patients. CONCLUSIONS: Among patients with a measured Spo(2) of 92-96%, greater variation in Sao(2) values at a given Spo(2) resulted in a higher occurence rate of both hypoxemia and hyperoxemia for Black patients compared with White patients.