Higher prevalence of occult hypoxemia found during anesthesia in Black patients compared to White patients

Background about the condition: Pulse oximeters are one of the most commonly utilized medical devices and a standard intraoperative monitor for patients under anesthesia. Studies have provided mixed results on the impact of dark skin pigmentation on pulse oximeter accuracy, but one recent study demonstrated a higher prevalence of unrecognized low oxygen levels in the blood despite normal pulse oximeter values in hospitalized patients. This has never been investigated in patients under anesthesia, but is important as pulse oximeter values impact patient care included removal of a breathing tube at the end of surgery or where the patient goes following surgery (e.g., home, recovery room, critical care unit).

What is the paper about: This large retrospective cohort study evaluated patients at a single center under anesthesia for surgery. All patients who had a measurement of blood oxygenation (e.g., arterial blood gas) during surgery were included in the study and their measured blood oxygen saturation was compared to their pulse oximeter reading at the same time. The primary outcome was occult hypoxemia, or a measured blood oxygen saturation (SaO2) < 88% despite a pulse oximeter reading (SpO2) > 92% as stratified by self-reported race/ethnicity. The study found the prevalence of occult hypoxemia to be significantly higher in Black (2.1%) and Hispanic (1.8%) patients when compared to White patients (1.1%), even after adjusting for other patient factors.