Abstract.
BACKGROUND: Recirculation of oxygenated blood in venovenous extracorporeal membrane oxygenation (VV ECMO) can decrease the oxygen delivery provided by the ECMO support. This study investigated the influence of central hemodynamics and catheter position on the amount of recirculation and oxygen delivery during VV ECMO.
METHODS: Recirculation was measured in seven newborn lambs (mean weight 4.7 kg) during VV ECMO using the ELSA Monitor (Transonic Systems, Inc., Ithaca, NY) and using the central venous line (CVL) method. The ECMO pump was set at the prescribed flow of 110–120 mL/kg/min for a targeted oxygen delivery rate of 6cc/kg/min without recirculation. Hemodynamic status before and during ECMO was also measured by the COstatus Monitor (Transonic Systems, Inc.,Ithaca, NY).
RESULTS: Lambs with a higher cardiac index (>160 ml/min/kg), had a tendency to have higher percent oxygen delivery (65–94%, at prescribed flow) while lambs with lower cardiac index (<150 ml/min/kg), tended to have lower percent oxygen delivery (39–62%, at prescribed flow). ELSA recirculation measurements had a squared correlation coefficient R2 = 0.8 with the CVL method.
CONCLUSIONS: The ELSA monitor provides an easy to use, non-invasive method to measure recirculation in VV ECMO. The data suggests that cardiac function may play an important prognostic role in achieving effective VV ECMO support.