NON-INVASIVE SPO₂/FIO₂ RATIO IS AN ACCURATE AND RELIABLE SURROGATE FOR PAO2/FIO2 RATIO IN SWINE WITH SEVERE SMOKE INHALATION/BURN-INDUCED ARDS AND 72-HOURS OF ICU CARE irubalca@student.uiwtx.edu

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NON-INVASIVE SPO₂/FIO₂ RATIO IS AN ACCURATE AND RELIABLE SURROGATE FOR PAO2/FIO2 RATIO IN SWINE WITH SEVERE SMOKE INHALATION/BURN-INDUCED ARDS AND 72-HOURS OF ICU CARE

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Andriy I. Batchinsky abatchinsky@genevausa.org Autonomous Reanimation and Evacuation Research Institute and Innovation Center, The Geneva Foundation Department of Translational Medicine San Antonio United States

United States

Oral or Poster

Burn patients are high-risk for acute-respiratory-distress-syndrome (ARDS), facing increased morbidity and mortality. Timely ARDS recognition enables appropriate triage and improved patient outcomes. PaO₂/FiO₂ ratio (PFR) is standard for ARDS classification but requires invasive arterial blood gas (ABG) sampling, often unavailable in low-resource or rapidly-evolving critical care settings. The noninvasive SpO₂/FiO₂ ratio (SFR) has shown promise in pediatric burns and in our prior severe injury models. Objective: Evaluate SFR as a continuous, noninvasive surrogate for intermittent PFR in severely burned, smoke-inhaled swine during 72-hr ICU management.

Anesthetized female Yorkshire swine (50-60kg, N=51) received 40% TBSA, full-thickness burns and smoke inhalation. Animals were randomly assigned to 1) standard-of-care-mechanical-ventilation (MV, n=14), or 2) MV+continuous extracorporeal-carbon-dioxide-removal (ECCO2R, n=17) or mesenchymal-stem-cell(MSC) administration at 0, 24, and 48hrs post-injury(n=20). Continuous SpO₂/FiO₂ monitoring yielded SFR; intermittent ABG provided PFR. Agreement was assessed by linear regression and Bland–Altman; ROC curves evaluated ARDS classification. SFR trends were analyzed over 72hrs, with p<0.05 considered significant.

SFR significantly and strongly correlated with PFR across 583 matched points(Spearman ρ = 0.71, R² = 0.69, p < 0.0001). Linear regression(Figure.1A) and Bland–Altman(Figure.1B) analyses confirmed SFR-PFR agreement, while ROC curves(Figure.2) demonstrated excellent discrimination across ARDS classifications. High threshold sensitivity and specificity demonstrated SFR’s ability to independently identify clinically relevant oxygenation ranges.

SFR is a reliable surrogate for PFR in burn-induced ARDS, remaining accurate across treatment effects. Its practicality in settings without ABG access, including resource-limited burn centers, forward surgical units, and preoperative triage, supports its integration into early burn evaluation to enable timely intervention.