Study site collaborators withdrew from participating due to time constraints.

This study is to test the usefulness of ultrasound dilution measurements in patients on extracorporeal membrane oxygenation. Measurements may include; efficiency of support (recirculation), amount of clotting in the oxygenator (oxygenator blood volume), and how well the heart is working (cardiac output). At the present time there are no devices available to perform these functions.

At the present time there are no devices available to measure recirculation, oxygenator blood volume and cardiac output in patients on extracorporeal membrane oxygenation. The study uses an external monitor, laptop computer, clamp on flowsensors and ultrasound dilution technology to measure blood flow. Measurements are made by injecting 0.5 - 1 ml/kg of sterile isotonic saline into the patient's extracorporeal circuit. The subject will be monitored throughout the measurements. The measurements will be coordinated with the regular care of the extracorporeal circuit.

Inclusion Criteria:

• Neonatal, pediatric or adult patients receiving venoarterial or venovenous extracorporeal membrane oxygenation.

Exclusion Criteria:

• Patients not receiving venoarterial or venovenous extracorporeal membrane oxygenation.

Measurement of cardiac output in venoarterial extracorporeal membrane oxygenation patients, recirculation in venovenous extracorporeal membrane oxygenation patients and oxygenator blood volume in venoarterial and venovenous extracorporeal membrane oxygenation patients.