Messai et al reported an equation for estimating the arterial oxygen saturation during venovenous extracorporeal membrane oxygenation (VV ECMO). The authors are from Centre Hospitalier de Cholet, Universite de Souk-Ahras (Algeria), University of Florence and Careggi Teaching Hospital (Florence).

Patient selection: VV ECMO for severe ARDS


The arterial oxygen saturation is about the same as the oxygen saturation in the pulmonary artery.



(1) EF = effective flow rate in L/min

(2) R = recirculation rate in percent

(3) PF = pump flow in L/min

(4) SmO2 = oxygen saturation of the blood leaving the oxygenator in percent

(5) CO = cardiac output in L/min

(6) SvO2 = oxygen saturation of mixed venous blood in percent

(7) PmO2 = partial oxygen pressure of the blood leaving the oxygenator in mm Hg

(8) delta oxygen saturation in mm Hg

(9) SdO2 = oxygen saturation in the drainage cannula


R =

= (SdO2 - SvO2) / (SmO2 - SvO2) * 100


EF =

= (1 - R) * PF


delta oxygen saturation =

= (0.01 * (PmO2))


arterial oxygen saturation in percent =

= ((EF / (CO) * SmO2) + ((1 - (EF/CO)) * SvO2) + (delta oxygen saturation)

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