The saga of equitable oxygen saturation measurement continues: The role of arterial blood gases

When patients develop critical illness, we anticipate their need for more frequent and timely care: more clinical assessments, diagnostic testing, and therapeutic interventions. Indeed, the concept of modern intensive care originated in the 1850s when clinicians recognized that some acute illnesses benefitted from more frequent nursing care; current ICU practice expands this routine monitoring to include frequent serum blood testing, which in some cases is performed several times in a given hour for a particular patient. Our hope is that more frequent and earlier diagnostic testing translates to earlier recognition of disease, more timely delivery of therapies, and prevention and reversal of organ dysfunction caused by critical illness.

We might therefore expect that arterial blood gas (ABG) testing would follow this paradigm given its central importance for guiding diagnosis and treatment of respiratory and metabolic disease syndromes. Additionally, growing recognition of diagnostic inaccuracy inherent to peripheral pulse oximeters might serve as further impetus for ABG testing, which is the gold standard for measuring arterial oxygen saturation. Recognized now for nearly four decades yet brought into public attention during the COVID-19 pandemic, skin-tone and racial disparities inherent to pulse oximeters—specifically over-estimation of arterial oxygen saturation in the setting of darker skin tone—exist despite the ubiquity of these devices for vital sign monitoring. This diagnostic inaccuracy disproportionately affects Black, Hispanic, and Asian patients, and creates a barrier to appropriate and equitable clinical treatment, notably for COVID-19 treatments.

Christopher F Chesley, George L Anesi