Correctly Establishing and Interpreting Oxygenation Status in Sickle Cell Disease

Abstract

Background As hypoxemia and hypoxia are central elements of disease pathophysiology and disease-related morbidity and mortality in individuals affected by sickle cell disease (SCD), clinical management aims to optimize oxygenation. Content Hypoxemia is primarily screened for with pulse oximetry. However, in SCD pulse oximetry can inaccurately reflect arterial saturation, posing the risk of undetected (occult) hypoxemia. Solely relying on pulse oximetry might therefore lead to misdiagnosis or mismanagement, with devastating effects on tissue oxygenation. The interpretation of oxygenation status is multifaceted, and “oxygen saturation” is often used as an umbrella term to refer to distinctly different measured quantities—estimated oxygen saturation (O2Sat), hemoglobin oxygen saturation (SO2) by either pulse oximetry or co-oximetry, and fractional oxyhemoglobin (FO2Hb). While in many clinical situations this ambiguous use is of little consequence, O2Sat, SO2, and FO2Hb cannot be used interchangeably in the setting of SCD, as dyshemoglobins, anemia, cardiopulmonary comorbidities, concomitant medications, and frequent transfusions need to be accounted for. This article describes the parameters that determine blood and tissue oxygen concentration, discusses laboratory method performance characteristics and the correct interpretation of currently available clinical laboratory testing, and reviews the literature on noninvasive vs invasive oxygenation measurements in SCD. Summary By correctly establishing and interpreting oxygenation parameters, clinical and laboratory teams can ensure high-quality, equitable healthcare, counteracting systemic exacerbations of health disparities frequently experienced by individuals with SCD.

Oxygen saturation thresholds in managing sickle cell disease at US children's hospitals

“…Altered oxyhemoglobin affinity due to hemoglobin S, dyshemoglobins, anemia, poor peripheral perfusion, impaired pulmonary diffusion, ventilation-perfusion mismatch, hypoventilation, and pulmonary hypertension often impair the accuracy of SpO 2 measurements in this population. 6,18 Furthermore, inaccurate pulse oximeter readings in patients from marginalized racial and ethnic groups has gained recent attention. Those with darker skin tones likely experience increased occult hypoxemia, 19,20 posing an added layer of risk to an already vulnerable SCD population who often encounter barriers to care, including racism and stereotyping.…”

“…Altered oxyhemoglobin affinity due to hemoglobin S, dyshemoglobins, anemia, poor peripheral perfusion, impaired pulmonary diffusion, ventilation‐perfusion mismatch, hypoventilation, and pulmonary hypertension often impair the accuracy of SpO 2 measurements in this population 6,18 . Furthermore, inaccurate pulse oximeter readings in patients from marginalized racial and ethnic groups has gained recent attention.…”