What is a sign of recirculation in ECMO?

A sign of recirculation in ECMO is indicated by an SVO2 difference of only 10-15%. Recirculation occurs when oxygenated blood from the ECMO circuit is reintroduced into the venous blood returning to the pump, leading to inadequate oxygenation of the patient. The SVO2 (mixed venous oxygen saturation) reflects the amount of oxygen remaining in the blood after it has passed through the body's tissues. When there is effective oxygenation and perfusion, an SVO2 difference of greater than 20% is typically expected. Therefore, a reading of only 10-15% suggests that the ECMO is not functioning optimally due to the recirculation phenomenon.

Monitoring the SVO2 differences is crucial in diagnosing potential complications, including recirculation, as significant deviations from expected values indicate that there may be inadequate oxygen delivery despite the ECMO support.