Optimising fluid therapy during venoarterial extracorporeal membrane oxygenation: current evidence and future directions

Abstract

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) offers an immediate and effective mechanical cardio-circulatory support for critically ill patients with refractory cardiogenic shock or selected refractory cardiac arrest. As fluid therapy is routinely performed as a component of initial hemodynamic resuscitation of ECMO supported patients, this narrative review intends to summarize the rationale and the evidence on the fluid resuscitation strategy in terms of fluid type and dosing, the impact of fluid balance on outcomes and fluid responsiveness assessment in VA-ECMO patients. Several observational studies have shown a deleterious impact of positive fluid balance on survival and renal outcomes. With regard to the type of crystalloids, further studies are needed to evaluate the safety and efficacy of saline versus balanced solutions in terms of hemodynamic stability, renal outcomes and survival in VA-ECMO setting. The place and the impact of albumin replacement, as a second-line option, should be investigated. During VA-ECMO run, the fluid management approach could be divided into four phases: rescue or salvage, optimization, stabilization, and evacuation or de-escalation. Echocardiographic assessment of stroke volume changes following a fluid challenge or provocative tests is the most used tool in clinical practice to predict fluid responsiveness. This review underscores the need for high-quality evidence regarding the optimal fluid strategy and the choice of fluid type in ECMO supported patients. Pending specific data, fluid therapy needs to be personalized and guided by dynamic hemodynamic approach coupled to close monitoring of daily weight and fluid balance in order to provide adequate ECMO flow and tissue perfusion while avoiding harmful effects of fluid overload.

Keywords: Critically ill patients; Extracorporeal membrane oxygenation; Fluid management; Fluid responsiveness.

Fig. 1

Intravascular volume deficit and triggers of fluid resuscitation in VA-ECMO setting. ROS: reactive oxygen species, iNOS: inducible nitric oxide synthase, ETCO₂: End-tidal carbon dioxide, CRT: Capillary refill time, MAP: Mean arterial pressure, SvO₂: Venous oxygen saturation, S_cvO₂: Central venous oxygen saturation

Fig. 2

ECMO drainage insufficiency: potential causes and pitfalls. VR: venous return, R_v: venous resistances, R_a: arterial resistances, Ao: aorta, CO: cardiac output. Created with BioRender.com

Fig. 3

Key determinants of ECMO flow rate and complications associated with inadequate fluid management in veno-arterial ECMO supported patients. MAP, mean arterial pressure, CO: cardiac output

Fig. 4

The ROSE concept of fluid therapy in VA-ECMO supported cardiogenic shock patients. IRI: ischemia-reperfusion injury, FR: Fluid responsiveness, CO: cardiac output, IABP: intra-aortic balloon pump, MAFP: Microaxial flow pump, MAP: mean arterial pressure, VTI: Velocity Time Integral, CRRT: continuous renal replacement therapy, GDFR: Goal directed fluid removal. Adapted from Malbrain et al. [73]