Racial Disparities in Occult Hypoxemia and Clinically Based Mitigation Strategies to Apply in Advance of Technological Advancements

BACKGROUND: Pulse oximetry is the mainstay of patient oxygen monitoring. Measurement error from pulse oximetry is more common for those with darker skin pigmentation, yet this topic remains understudied, and evidence-based clinical mitigation strategies do not currently exist. Our objectives were to measure the rate of occult hypoxemia, defined as arterial oxygen saturation (SaO2) < 88% when pulse oximeter oxygen saturation was between 92-96%, in a racially diverse critically ill population; to analyze degree, direction, and consistency of measure-ment error; and to develop a mitigation strategy that minimizes occult hypoxemia in advance of technological advancements. METHODS: We performed a multi-center retrospective cohort study of critically ill subjects. RESULTS: Among 105,467 paired observations from 7,693 sub-jects, we found occult hypoxemia was more common among minority subjects. The frequency of occult hypoxemia was 7.9% versus 2.9% between Black and white subjects, respectively, (P < .001). Pulse oximeter measurement errors were inconsistent throughout a patient encounter, with 67% of encounters having a range of intra-subject measurement errors > 4 percentage points. In 75% of encounters, the intra-subject errors were bidirectional. SaO2 < 88% was less common at higher pulse oximeter oxygenation ranges (4.1% and 1.8% of observations among Black and white subjects at a pulse oximeter threshold of 94-98%). Although occult hypoxemia was further reduced at oxygenation saturation range 95-100%, the frequency of hyperoxemia (partial pressure of arterial oxygen > 110 mm Hg) became more common, occurring in 42.3% of Black and 46.0% of white observations. CONCLUSIONS: Measurement error in pulse oxime-try is common for all racial groups, but occult hypoxemia occurred most commonly in Black subjects. The highly variable magnitude and direction of measurement error preclude an indi-vidualized mitigation approach. In advance of technological advancements, we recommend tar-geting a pulse oximetry saturation goal of 94-98% for all patients.