Background In patients with severe cardiorespiratory instability ECMO can be used as lifesaving therapy. Many of these patients are at risk of cerebral hypoxia preECMO. As such greater focus is turned to neuro-protective strategies in order to provide the best possible outcome.

Methods Observational study during veno-venous and veno-arterial ECMO. Real-time regional oxygenation, right and left cerebral cortex of the watershed region, was measured with the INVOS 5100 continuously.

Results 21 patients where measured, 17 on veno-arterial (VA) mode, 4 on veno-venous (VV) mode. The difference of right minus left rSO₂ compared in VV-ECMO versus VA-ECMO (resp. 23457 and 53821 measured points) is VV median difference of 0 (interquartile range −7 to 7), VA difference of 4 (interquartile range −9 to 17).

Secondly we evaluated the correlation of the mean rSO₂ and central venous oxygen saturation (SvO₂); resp. VV (160 measured points) −0.078 (p = 0.327) versus VA (339 measured points) 0.384 (p = 0.000).

Conclusions We found no significant difference between VV and VA right and left rSO₂ mean difference, which suggests no decrease in right oxygen supply in VA-ECMO patients despite right carotid artery ligation.

Secondly we found no significant correlation between rSO₂ and SvO₂ in VV-ECMO compared to a significant correlation in VA-ECMO. In VA-ECMO SvO₂ also is a measurement of oxygen supply versus oxygen demand at the tissue level, whereas in VV-ECMO SvO₂ is considered to be a parameter of recirculation rather than oxygen consumption of the individual patient.