Abstract
IntroductionDifferential hypoxia is a pivotal problem in patients with femoral veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) support. Despite recognition of differential hypoxia and attempts to deliver more oxygenated blood to the upper body, the mechanism of differential hypoxia as well as prevention strategies have not been well investigated.MethodsWe used a sheep model of acute respiratory failure that was supported with femoral VA ECMO from the inferior vena cava to the femoral artery (IVC-FA), ECMO from the superior vena cava to the FA (SVC-FA), ECMO from the IVC to the carotid artery (IVC-CA) and ECMO with an additional return cannula to the internal jugular vein based on the femoral VA ECMO (FA-IJV). Angiography and blood gas analyses were performed.ResultsWith IVC-FA, blood oxygen saturation (SO2) of the IVC (83.6 ± 0.8%) was higher than that of the SVC (40.3 ± 1.0%). Oxygen-rich blood was drained back to the ECMO circuit and poorly oxygenated blood in the SVC entered the right atrium (RA). SVC-FA achieved oxygen-rich blood return from the IVC to the RA without shifting the arterial cannulation. Subsequently, SO2 of the SVC and the pulmonary artery increased (70.4 ± 1.0% and 73.4 ± 1.1%, respectively). Compared with IVC-FA, a lesser difference in venous oxygen return and attenuated differential hypoxia were observed with IVC-CA and FA-IJV.ConclusionsDifferential venous oxygen return is a key factor in the etiology of differential hypoxia in VA ECMO. With knowledge of this mechanism, we can apply better cannula configurations in clinical practice.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-015-0791-2) contains supplementary material, which is available to authorized users.
Highlights
Differential hypoxia is a pivotal problem in patients with femoral veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) support
Upper body hypoxia in the acute respiratory failure (ARF) sheep model supported with inferior vena cava (IVC)-femoral artery (FA) Hemodynamic parameters, including heart rate (HR) and mean arterial pressure (MAP), were stable in each group of animals throughout the experiment and no significant differences were present among groups
In conclusion, our study indicates that differential venous oxygen return is a key factor in the etiology of differential hypoxia in veno-arterial ECMO (VA ECMO)
Summary
Differential hypoxia is a pivotal problem in patients with femoral veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) support. Because hypoxemia occurs in the upper body, dual circulation has been proposed as the major reason for differential hypoxia in patients with femoral VA ECMO (from the inferior vena cava to the femoral artery, IVC-FA) [14,15]. According to this theory, in VA ECMO, oxygenated blood from the ECMO circuit enters the descending aorta to perfuse the lower body, whereas the blood flow of the upper body is from the left ventricle [14]. To deliver more oxygenated blood to the upper body, some clinicians have suggested: (1) to modify FA cannulation to the axillary artery or carotid artery cannulation (IVC-CA) [20,21]; or (2) to use veno-arterio-venous ECMO by adding an additional venous reinfusion cannula in the internal jugular vein to IVCFA (FA-IJV) [17]
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