Impact of bypass flow rate and catheter position in veno-venous extracorporeal membrane oxygenation on gas exchange in vivo

Abstract

The clinical use of veno-venous extracorporeal membrane oxygenation (VVECMO) in adult patients with respiratory failure is rapidly increasing. However, recirculation of blood oxygenated by ECMO back into the circuit may occur in VVECMO, resulting in insufficient oxygenation. The cannula position and bypass flow rate are two major factors influencing recirculation, but the relationship and ideal configuration of these factors are not fully understood. In the present study, we attempted to clarify these parameters for effective gas exchange. VVECMO was performed in eight adult goats under general anesthesia. The position of the drainage cannula was fixed in the inferior vena cava (IVC), but the return cannula position was varied between the IVC, right atrium (RA), and superior vena cava (SVC). At each position, the recirculation rates calculated, and the adequacy of oxygen delivery by ECMO in supplying systemic oxygen demand was assessed by measuring the arterial oxygen saturation (SaO2) and pressure (PaO2). Although the recirculation rates increased as the bypass flow rates increased, SaO2 and PaO2 also increased in any position of return cannula. The recirculation rates and PaO2 were 27 ± 2% and 162 ± 16 mmHg, 36 ± 6% and 139 ± 11 mmHg, and 63 ± 6% and 77 ± 9 mmHg in the SVC, RA and IVC position at 4 L/min respectively. In conclusion, the best return cannula position was the SVC, and a high bypass flow rate was advantageous for effective oxygenation. Both the bypass flow rates and cannula position must be considered to achieve effective oxygenation.

The Role of Echocardiography in Neonates and Pediatric Patients on Extracorporeal Membrane Oxygenation

“…The return cannula is usually inserted into the internal jugular vein and advanced through the SVC to the mid-right atrium. If the two tips are located too close together, recirculation may occur, resulting in hypoxemia ( 87 , 88 ).…”

Optimal drainage cannula position in dual cannulation for veno-venous extracorporeal membrane oxygenation

“…In the SVC return cannula position, the recirculation fraction was the lowest and the blood oxygenation was the highest. 4 In previous study, as the distance between the drainage and return ports was large, the recirculation fraction was low and the blood oxygenation tended to get better. Therefore, we hypothesized that the preferable drainage cannula position would be the lower IVC because the distance between the drainage and return ports was large.…”

“…This finding is consistent with our previous report. 4 Although above findings included several limitations: (1) flow rate was lower than 3 L/min, (2) small number of trials was done (n = 4), (3) no disease models were investigated, and so on. Further study may be necessary to answer the effect of these factors together with the numerical analysis with the fluid dynamic simulation software.…”

“…Previously, we investigated the return cannula position when the drainage cannula was fixed in the IVC. 4 With respect to blood oxygenation, the optimal return cannula position was the SVC; however, the optimal drainage cannula position has not yet been fully clarified. Therefore, this study evaluated the preferred drainage cannula position among the lower IVC, the upper IVC, and the RA.…”

Establishment of a novel miniature veno‐venous extracorporeal membrane oxygenation model in the rat

“…In previous studies, we studied recirculation and cannulas during V-V ECMO in large animal models. 20,21 This time, we are not considering recirculation in this V-V ECMO model, though conventional V-V ECMO usually includes double cannulation (cannulation of two venous vessels). The possibility of recirculation cannot be excluded in this method.…”