Introduction

Veno-arterial ECMO allows gas exchange and pumps blood from a vein to an artery. It is used to support failing lungs and can be used to support a failing heart.

Veno-arterial ECMO allows stabilization of the patient by perfusing vital organs with oxygenated blood. During veno-arterial ECMO, both the ECMO and the heart pump blood around the patient’s body.

If no gas is flowing through the oxygenator, deoxygenated venous blood will be pumped into the arterial circulation, creating a veno-arterial shunt.

Veno-arterial ECMO will be continued until the clinical team has decided the best treatment for a specific patient. Two circulations having to work in parallel renders the management of the patient on veno-arterial ECMO much more complex than veno-venous ECMO. Patients may rapidly develop complications.

Patients supported with veno-arterial ECMO frequently have other organ failure and require a high level of critical care support. The day-to-day management of patients on veno-arterial ECMO is the same as for all critically ill patients, plus some specific elements. This chapter describes these specific elements.

Locally agreed protocols for the care of ECMO patients should be incorporated into training.

Monitoring of the patient on veno-arterial ECMO has been described in Chapter 4.

Stabilization on veno-arterial ECMO

Insertion of ECMO cannulas should ideally take place in an operating room. A variety of configurations can be used.

Peripheral cannulation can be achieved percutaneously and does not require surgery. Central and direct cannulation require surgery.

It can be striking how rapidly pharmacological support can be modified after veno-arterial ECMO support has been started. Inotropes and other vasoactive drugs can often be decreased.

It is essential to ensure that the heart continues to eject to avoid thrombosis in the cardiac cavities. Maintaining pulmonary blood flow may also prevent the formation of intrapulmonary thrombi. The absence of ventricular ejection will lead to cardiac distension and prevent possible cardiac recovery.

Lung ventilation can be adapted immediately after veno-arterial ECMO has been established. Similar principles of applying the least-damaging ventilation, as in veno-venous ECMO, should be applied (see Chapter 8). It is essential to ensure that the lungs still provide gas exchange, as the blood going through the lungs will need to be oxygenated (and CO₂ removed) to avoid a hypoxic mixture being delivered to some tissues (e.g. the coronary arteries). Changes in mechanical ventilation can affect the venous return and modify both cardiac output and ECMO flow.

After stabilization, the patient can undergo multiple non-invasive tests to determine the cause and decide subsequent management.