Characterizing the Racial Discrepancy in Hypoxemia Detection in VV-ECMO: An ELSO Registry Analysis.

Importance: Skin pigmentation influences peripheral oxygen saturation (SpO ₂ ) measured by pulse oximetry compared to the arterial saturation of oxygen (SaO ₂ ) measured via arterial blood gas analysis. However, data on SpO ₂ -SaO ₂ discrepancy are limited in venovenous-extracorporeal membrane oxygenation (VV-ECMO) patients.
Objective: To determine whether there is racial/ethnical discrepancy between SpO ₂ and SaO ₂ in patients receiving VV-ECMO. We hypothesized VV-ECMO cannulation, in addition to race/ethnicity, accentuates the SpO ₂ -SaO ₂ discrepancy due to significant hemolysis.
Design: Retrospective cohort study of the Extracorporeal Life Support Organization Registry from 1/2018-5/2023.
Setting: International, multicenter registry study including over 500 ECMO centers.
Participants: Adults (≥ 18 years) supported with VV-ECMO with concurrently measured SpO ₂ and SaO ₂ measurements.
Exposure: Race/ethnicity and ECMO cannulation.
Main Outcomes and Measures: Occult hypoxemia (SaO ₂ ≤ 88% with SpO ₂ ≥ 92%) was our primary outcome. Multivariable logistic regressions were performed to examine whether race/ethnicity was associated with occult hypoxemia in pre-ECMO and on-ECMO SpO ₂ -SaO ₂ calculations. Covariates included age, sex, temporary mechanical circulatory support, pre-vasopressors, and pre-inotropes for pre-ECMO analysis, plus single-lumen versus double-lumen cannulation, hemolysis, hyperbilirubinemia, ECMO pump flow rate, and on-ECMO 24h lactate for on-ECMO analysis.
Results: Of 13,171 VV-ECMO patients (median age = 48.6 years, 66% male), there were 7,772 (59%) White, 2,114 (16%) Hispanic, 1,777 (14%) Black, and 1,508 (11%) Asian patients. The frequency of on-ECMO occult hypoxemia was 2.0% ( N = 233). Occult hypoxemia was more common in Black and Hispanic versus White patients (3.1% versus 1.7%, P < 0.001 and 2.5% versus 1.7%, P = 0.025, respectively).In multivariable logistic regression, Black patients were at higher risk of pre-ECMO occult hypoxemia versus White patients (adjusted odds ratio [aOR] = 1.55, 95% confidence interval [CI] = 1.18-2.02, P = 0.001). For on-ECMO occult hypoxemia, Black patients (aOR = 1.79, 95%CI = 1.16-2.75, P = 0.008) and Hispanic patients (aOR = 1.71, 95%CI = 1.15-2.55, P = 0.008) had higher risk versus White patients. Furthermore, higher pump flow rate (aOR = 1.29, 95%CI = 1.08-1.55, P = 0.005) and higher on-ECMO 24h lactate (aOR = 1.06, 95%CI = 1.03-1.10, P < 0.001) significantly increased the risk of on-ECMO occult hypoxemia.
Conclusions and Relevance: Hispanic and Black VV-ECMO patients experienced occult hypoxemia more than White patients. SaO ₂ should be carefully monitored during ECMO support for Black and Hispanic patients especially for those with high pump flow and lactate values at risk for occult hypoxemia.
Competing Interests: Dr. Tonna is supported by a Career Development Award from the National Institutes of Health/National Heart, Lung, And Blood Institute (K23 HL141596). Dr. Tonna is the Chair of the Registry Committee of the Extracorporeal Life Support Organization (ELSO). Dr. Brodie receives research support from and consults for LivaNova. He has been on the medical advisory boards for Abiomed, Xenios, Medtronic, Inspira and Cellenkos. He is the President-elect of the Extracorporeal Life Support Organization (ELSO) and the Chair of the Executive Committee of the International ECMO Network (ECMONet), and he writes for UpToDate. Dr. Lorusso is a consultant for Medtronic, LivaNova, Getinge and ASbiomed, and Member of the Medical Advisory Board of Eurosets and Xenios. He is the ELSO Research Committee Chair, and Honorary Secretary of EuroELSO. The authors do not have any additional conflicts of interest to declare. SPK is supported by NHLBI (5K08HL14332). SMC is supported by NHLBI (1K23HL157610).Disclosures: The authors have nothing to disclose