Hemodynamic Monitoring and Fluid Responsiveness in Venovenous Extracorporeal Membrane Oxygenation (VV ECMO) - "HemodynamECMOnitoring-VV Study"

Validation of Techniques for Hemodynamic Monitoring and Prediction of Fluid Responsiveness in Patients Undergoing Venovenous Extracorporeal Membrane Oxygenation - A Prospective Diagnostic Accuracy Study ("HemodynamECMOnitoring-VV Study")

In extracorporeal membrane oxygenation (ECMO), blood is drawn out of the body via tubes, oxygenated in an artificial lung; and then pumped back into the blood vessels. This allows the supply of oxygen-rich blood to the organs (brain, heart, lungs, kidneys, liver, intestines, etc.) to be maintained.

Continuous monitoring of cardiac function and circulatory status (blood pressure, blood flow to organs) is very important in intensive care medicine in order to control the administration of circulation-supporting medication and infusions. Various devices are routinely used for this task. However, in the specific situation of ECMO treatment, the measurements of these devices could be affected due to the artificial circulation; outside the body.

The purpose of this study is therefore to test the accuracy of different methods of circulation monitoring during ECMO treatment.

Hemodynamic monitoring and tests for fluid responsiveness are cornerstones of intensive care medicine.

Generally, hemodynamic measurements can be obtained, for instance, with the following methods: pulmonary artery catheter, transthoracic echocardiography (TTE), esophageal doppler, transpulmonary thermodilution, pulse contour analysis and bioreactance, amongst others.

Maneuvers for assessing volume responsiveness include passive leg raising (PLR), respiratory pulse pressure variation (PPV), stroke volume variation (SVV), inferior vena cava ultrasound (IVC), and end-inspiratory or end-expiratory occlusion tests.

While these commonly used methods of hemodynamic assessment have been validated in various clinical scenarios, data are lacking in the setting of venovenous extracorporeal membrane oxygenation (VV ECMO). VV ECMO is commonly used for respiratory support in patients with severe acute respiratory failure. Blood is usually drained from a femoral vein, pumped through an oxygenator, where it is oxygenated and decarboxylated, and thereafter reinfused into the patient via a central venous, most commonly jugular, return cannula. Theoretically, the artificial circulation with its blood drainage and return flows may interfere with common hemodynamic monitoring techniques and lead to erroneous measurements.

The aim of this study therefore is to validate select techniques of hemodynamic monitoring and assessment of fluid responsiveness in patients on VV ECMO.

In the context of this study, the performance of different hemodynamic monitoring tools and techniques for predicting fluid responsiveness will be compared.

Inclusion Criteria:

• Patient receiving VV-ECMO support
• Age 18 - 75 years

Exclusion Criteria:

• Pregnancy
• Conditions not allowing for passive leg raising maneuvers, e.g. "open abdomen", known or suspected elevation of intracranial pressure, recent leg or spinal trauma or orthopedic conditions not permitting leg raising
• Known ischemic or hemorrhagic stroke within 3 months prior to study enrollment.

Suspicion of raised intracranial pressure is defined as pupil divergence (if not yet further clarified radiographically/neurologically/ophthalmologically) or signs detected in routine computed tomography scans (compressed or elapsed basal cisterns or midline shift > 5 mm.