Ultrasound Dilution Measurement of Cardiac Output Before and After Adult Cardiopulmonary Bypass

Cardiac output, the amount of blood pumped by the heart in one minute, will be measured in adults undergoing surgery involving cardiopulmonary bypass. Cardiac output will be measured before and after cardiopulmonary bypass using a device that employs ultrasound dilution technology. The ultrasound dilution cardiac output measurements will be validated or compared with cardiac output measurements made using thermodilution, which is the current "gold standard."