Overt and Occult Hypoxemia in Patients Hospitalized With COVID-19. (20th January 2023)

• Record Type: Journal Article
• Authors: Gadrey, Shrirang M.; Mohanty, Piyus; Haughey, Sean P.; Jacobsen, Beck A.; Dubester, Kira J.; Webb, Katherine M.; Kowalski, Rebecca L.; Dreicer, Jessica J.; Andris, Robert T.; Clark, Matthew T.; Moore, Christopher C.; Holder, Andre; Kamaleswaran, Rishi; Ratcliffe, Sarah J.; Moorman, J. Randall
• Is Part Of: Critical care explorations. Volume 5:Number 1(2023)
• Page Start: e0825
• Publication Date: 2023-01-20
• Subjects: COVID-19 -- hospital mortality -- organ dysfunction scores -- prognosis -- respiratory failure
• DOI: 10.1097/CCE.0000000000000825
• Languages: English
• ISSNs: 2639-8028

Abstract

Abstract : IMPORTANCE: Progressive hypoxemia is the predominant mode of deterioration in COVID-19. Among hypoxemia measures, the ratio of the Pao 2 to the Fio 2 (P/F ratio) has optimal construct validity but poor availability because it requires arterial blood sampling. Pulse oximetry reports oxygenation continuously (ratio of the Spo 2 to the Fio 2 [S/F ratio]), but it is affected by skin color and occult hypoxemia can occur in Black patients. Oxygen dissociation curves allow noninvasive estimation of P/F ratios (ePFRs) but remain unproven. OBJECTIVES: Measure overt and occult hypoxemia using ePFR. DESIGN, SETTING, AND PARTICIPANTS: We retrospectively studied COVID-19 hospital encounters ( n = 5, 319) at two academic centers (University of Virginia [UVA] and Emory University). MAIN OUTCOMES AND MEASURES: We measured primary outcomes (death or ICU transfer within 24 hr), ePFR, conventional hypoxemia measures, baseline predictors (age, sex, race, comorbidity), and acute predictors (National Early Warning Score [NEWS] and Sequential Organ Failure Assessment [SOFA]). We updated predictors every 15 minutes. We assessed predictive validity using adjusted odds ratios (AORs) and area under the receiver operating characteristic curves (AUROCs). We quantified disparities (Black vs non-Black) in empirical cumulative distributions using the Kolmogorov-Smirnov (K-S) two-sample test. RESULTS: Overt hypoxemia (low ePFR) predicted bad outcomes (AOR for a 100-point ePFR drop: 2.7 [UVA]; 1.7 [Emory]; p < 0.01) with better discrimination (AUROC: 0.76 [UVA]; 0.71 [Emory]) than NEWS (0.70 [both sites]) or SOFA (0.68 [UVA]; 0.65 [Emory]) and similar to S/F ratio (0.76 [UVA]; 0.70 [Emory]). We found racial differences consistent with occult hypoxemia. Black patients had better apparent oxygenation (K-S distance: 0.17 [both sites]; p < 0.01) but, for comparable ePFRs, worse outcomes than other patients (AOR: 2.2 [UVA]; 1.2 [Emory]; p < 0.01). CONCLUSIONS AND RELEVANCE: The ePFR was a valid measure of overt hypoxemia. In COVID-19, it may outperform multi-organ dysfunction models. By accounting for biased oximetry as well as clinicians' real-time responses to it (supplemental oxygen adjustment), ePFRs may reveal racial disparities attributable to occult hypoxemia.