oxygenation
OI = (FiO₂ × MAP × 100) ÷ PaO₂
Normal: < 5 (normal neonates)
Normal: 0.21–1.0
Normal: Varies by settings
Normal: 50–80 mmHg neonates
The oxygenation index is primarily used in neonatal and pediatric intensive care. It incorporates mean airway pressure (MAP) — the driving force for oxygenation — in addition to FiO₂ and PaO₂. A higher OI indicates more severe oxygenation failure because the patient requires higher MAP and/or FiO₂ to achieve the same PaO₂.
Used in neonatal respiratory care (RDS, PPHN) and pediatric ARDS to quantify oxygenation failure severity and guide ECMO referral. OI > 25 indicates severe impairment; OI > 40 for 4+ hours is a traditional ECMO threshold in neonates. Adults with ARDS may also have OI calculated.
Normal neonate
→ 2.24
Normal oxygenation index
Severe PPHN on HFOV
→ 40
OI 40 — meets threshold for ECMO consideration in neonates
OI accounts for the 'cost' of oxygenation in terms of ventilator support. A neonate with PaO₂ 60 on FiO₂ 1.0 and MAP 18 has OI = (1.0 × 18 × 100) / 60 = 30 — indicating severe disease. The P/F ratio alone would miss the impact of high airway pressures. In neonates with PPHN, OI > 40 typically indicates ECMO consideration.