A novel oxygenation distension index (ODI): a driving pressure-based metric compared with the oxygenation index in pediatric PARDS.

UNLABELLED: The oxygenation index (OI) is widely used to assess disease severity in pediatric ARDS; however, it relies on mean airway pressure (Pmean), which does not reflect lung-distending forces relevant to ventilator-induced lung injury. Driving pressure (DP) is a determinant of lung strain. We developed and evaluated the oxygenation distension index (ODI) by substituting DP for Pmean in the OI formula. This observational study included children aged 1 month to 18 years with PARDS requiring ≥ 24 h of invasive mechanical ventilation in six centers. Lung ultrasound scores (LUS) and respiratory mechanics, including transpulmonary pressure (PL), transpulmonary driving pressure (DPL), mechanical power (MP), and transpulmonary mechanical power (MPL), were assessed 4-24 h after diagnosis according to PALICC-2 recommendations. Associations of OI and ODI with lung injury markers and clinical outcomes were analyzed. Among 56 patients, 41 (73%) had mild-to-moderate and 15 (27%) had severe PARDS. ODI demonstrated stronger correlations than OI with lung injury markers, including LUS (r = 0.818 vs. 0.501), PL (r = 0.779 vs. 0.697), DPL (r = 0.745 vs. 0.671), MP normalized to predicted body weight (r = 0.518 vs. 0.438), and MPL normalized to predicted body weight (r = 0.634 vs. 0.628). For 30-day mortality prediction, ODI showed higher discriminative performance than OI (AUC 0.740 [95% CI, 0.598-0.866] vs. 0.685 [95% CI, 0.535-0.835]; DeLong p = 0.040).

CONCLUSIONS

By incorporating driving pressure, ODI more closely reflects lung injury severity than the conventional oxygenation index and improves discrimination for mortality in PARDS.

WHAT IS KNOWN: • The oxygenation index is the standard metric used for severity classification in pediatric acute respiratory distress syndrome. • Driving pressure has been increasingly recognized as a key physiological determinant of lung injury and clinical outcomes in ARDS.

WHAT IS NEW: • A driving pressure-based oxygenation metric, the oxygenation distension index (ODI), shows stronger associations with established markers of lung injury than the conventional oxygenation index in PARDS. • ODI provides improved discrimination for 30-day mortality compared with the oxygenation index in mechanically ventilated children with PARDS.