Oxygenation Index Calculator
OI = (FiO₂ × mean airway pressure × 100) / PaO₂
Version 1.0.0
Inspired oxygen (FiO₂)
Mean airway pressure
cm H₂O
Arterial oxygen tension (PaO₂)
Mean airway pressure helper
For non-invasive ventilation/bilevel positive airway pressure. This is a time-weighted pressure estimate, not a measured mean airway pressure.
Inspiratory positive airway pressure
cm H₂O
Expiratory positive airway pressure
cm H₂O
Inspiratory time (TI)
s
Respiratory rate
/min
Estimated mean airway pressure
— cm H₂O
Oxygenation Index
—
Dimensionless; interpret in the relevant clinical context.
Unable to calculate.
No clinical values are intentionally saved by this control.
Equations
Oxygenation Index
OI = (FiO₂ × MAP × 100) / PaO₂FiO₂ is entered as a fraction (or converted from percentage); MAP is mean airway pressure in cm H₂O; PaO₂ is arterial oxygen tension in mm Hg. PaO₂ entered in kPa is converted using 1 kPa = 7.5 mm Hg. The displayed OI is rounded to the nearest integer.
Mean airway pressure helper (NIV/BiPAP estimate)
Ttot = 60 / RR; TE = Ttot − TI; estimated MAP = IPAP × (TI / Ttot) + EPAP × (TE / Ttot)IPAP and EPAP are in cm H₂O, TI and Ttot are in seconds, and RR is breaths/min. TI must be shorter than Ttot and IPAP must not be lower than EPAP. The helper display and the value transferred to the primary calculation are rounded to the nearest integer.
References
- Montgomery AB, Stager MA, Carrico CJ, Hudson LD. Causes of mortality in patients with the adult respiratory distress syndrome. Am Rev Respir Dis. 1985;132(3):485-489. PMID: 3929686 DOI: 10.1164/arrd.1985.132.3.485
- Flori HR, Glidden DV, Rutherford GW, Matthay MA. Pediatric acute lung injury: prospective evaluation of risk factors associated with mortality. Am J Respir Crit Care Med. 2005;171(9):995-1001. PMID: 15665325 DOI: 10.1164/rccm.200404-544OC
- Palmero J, Lasa JJ, Del Castillo J, et al. Oxygenation index as predictor of outcome in pediatric acute lung injury. Pediatr Pulmonol. 2010;45(2):123-129. PMID: 20013769 DOI: 10.1002/ppul.21143