Introduction: ICU monitor pulse oximetry (SpO2) underestimates hypoxia in individuals with darker skin pigmentation. Newly transplanted hyperbilirubinemic liver failure (LF) patients with jaundiced skin may plausibly also suffer erroneous SpO2 overestimation. We hypothesized that hyperbilirubinemia in newly transplanted LF patients degrades SpO2 pulse oximetry accuracy. Methods: This retrospective single-center study extracted ICU registry data of patients who underwent liver transplantation from 2018-2023. SaO2 (arterial blood gas)/SpO2 (ICU monitor pulse oximetry) ratios were obtained in the 1st 36-hours post-transplant with a ratio of 1 indicating SaO2 and SpO2 concordance. Pearson correlation coefficients identified whether bilirubin concentration affected SaO2/SpO2 ratios, and whether this was influenced by race, sex, age, or BMI. Results: 203 patients (52 Black, 116 White; age 19-72 years) met criteria. 83 patients were female. Common LF etiologies included alcoholic, autoimmune, and viral hepatitis. Bivariate analysis demonstrated a significant inverse relationship between SaO2/SpO2 and bilirubin in all patients (r= -0.26, p< 0.001) with higher bilirubin associated with greater SpO2 overestimation. Overestimation was particularly observed in White (r= -0.33, p< 0.001) but not Black patients (r= -0.11, p=0.42). Males (r= -0.29, p< 0.01) and those with a BMI of 25-30 (r= -0.48, p< 0.001) demonstrated a significant inverse relationship between bilirubin and SaO2/SpO2. Conclusions: Newly transplanted hyperbilirubinemic LF patients suffer from SpO2-based oxygenation overestimation compared to arterial SaO2. This is particularly observed in Whites, males, and individuals with a BMI of 25-30 who demonstrate a significant inverse correlation between bilirubin level and SaO2/SpO2. These factors may lead to overestimation of oxygenation and failure to recognize and rescue patients from hypoxemia during periods of organ vulnerability.
Wynveen et al. (Sun,) studied this question.