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.
Parameters:
(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)
