Pulse oximetry is ubiquitous in anesthesia and is generally a reliable noninvasive measure of arterial oxygen saturation. Concerns regarding the impact of skin pigmentation and race/ethnicity on the accuracy of pulse oximeter accuracy exist. The authors hypothesized a greater prevalence of occult hypoxemia (arterial oxygen saturation [Sao2] less than 88% despite oxygen saturation measured by pulse oximetry [Spo2] greater than 92%) in patients undergoing anesthesia who self-reported a race/ethnicity other than White.


Demographic and physiologic data, including self-reported race/ethnicity, were extracted from a departmental data warehouse for patients receiving an anesthetic that included at least one arterial blood gas between January 2008 and December 2019. Calculated Sao2 values were paired with concurrent Spo2 values for each patient. Analysis to determine whether Black, Hispanic, Asian, or Other race/ethnicities were associated with occult hypoxemia relative to White race/ethnicity within the Spo2 range of 92 to 100% was completed.


In total, 151,070 paired Sao2–Spo2 readings (70,722 White; 16,011 Black; 21,223 Hispanic; 8,121 Asian; 34,993 Other) from 46,253 unique patients were analyzed. The prevalence of occult hypoxemia was significantly higher in Black (339 of 16,011 [2.1%]) and Hispanic (383 of 21,223 [1.8%]) versus White (791 of 70,722 [1.1%]) paired Sao2–Spo2 readings (P < 0.001 for both). In the multivariable analysis, Black (odds ratio, 1.44 [95% CI, 1.11 to 1.87]; P = 0.006) and Hispanic (odds ratio, 1.31 [95% CI, 1.03 to 1.68]; P = 0.031) race/ethnicity were associated with occult hypoxemia. Asian and Other race/ethnicity were not associated with occult hypoxemia.


Self-reported Black and Hispanic race/ethnicity are associated with a greater prevalence of intraoperative occult hypoxemia in the Spo2 range of 92 to 100% when compared with self-reported White race/ethnicity.

Editor’s Perspective
What We Already Know about This Topic
  • Pulse oximetry is part of the American Society of Anesthesiologists’ Standards for Basic Anesthetic Monitoring
  • Pigmentation in dark skin has been associated with overestimation of pulse oximeter values
  • Recent critical care literature has renewed concerns regarding the accuracy of pulse oximetry in detecting hypoxemia in Black versus White patients
What This Article Tells Us That Is New
  • Among 46,523 patients with 151,070 paired arterial oxygen saturation (Sao2)–oxygen saturation measured by pulse oximetry (Spo2) intraoperative readings at a single center, the prevalence of occult hypoxemia (Sao2 less than 88% despite concurrent Spo2 greater than 92%) was significantly increased in patients self-reporting Black (2.1%) and Hispanic (1.8%) race/ethnicity compared with patients self-reporting White (1.1%) race/ethnicity
  • After adjusting for other clinical factors, Black or Hispanic race/ethnicity was independently associated with occult hypoxemia