A 50-year-old man on ICU with ARDS is receiving VV-ECMO. His SpO2 measured by pulse oximetry is 82%, but the PaO2 on ABG from the right radial artery is 9.5 kPa (normal). What explains this discrepancy?APulse oximetry is always accurateBIn VV-ECMO, oxygenated blood from the circuit mixes with deoxygenated blood in the right heart; if recirculation is significant, the SaO2 (and thus SpO2) may be lower than expected despite adequate PaO2 - additionally, the mixing point varies with native cardiac output, and upper body SpO2 may differ from lower body if there is differential flowCThe ABG is wrongDThe pulse oximeter is brokenESpO2 and PaO2 always correlate perfectlyCheck my answer