Pulse Oximetry Overestimates Arterial Oxygen Saturation and Alters Fick-Derived Hemodynamics During Right Heart Catheterization

Pulse oximetry (SpO 2 ) is widely used as a surrogate for arterial oxygen saturation (SaO 2 ); however, device and physiologic limitations can introduce systematic error, particularly in cardiopulmonary disease, low perfusion states, and across varying skin tones. 1,2In invasive hemodynamic assessment, this discrepancy is clinically relevant because SaO 2 directly determines arterial oxygen content and therefore influences Fick-derived cardiac output (CO) and vascular resistance calculations. 3Despite this dependency, SpO 2 is occasionally substituted for SaO 2 during catheterization workflows when arterial sampling is unavailable or delayed.We sought to quantify the frequency and hemodynamic impact of SpO 2 -SaO 2 discordance during routine right heart catheterization.We performed a retrospective cohort analysis of 50 consecutive patients undergoing combined right and left heart catheterization with simultaneous pulse oximetry and direct SaO 2 measurement between August 2023 and March 2024 at a single center.Patients demonstrating an SpO 2 -SaO 2 difference 5 percentage points comprised the analytic cohort.This threshold was selected to capture clearly clinically meaningful discordance beyond expected device variability.