Lack of enrollment

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."

Inclusion Criteria:

• Patients aged > 21 years
• Patients undergoing surgery involving cardiopulmonary bypass
• Patients instrumented with a thermodilution catheter

Exclusion Criteria:

• Patients aged < 21 years
• Patients undergoing surgery "off pump" (not involving cardiopulmonary bypass)

Measurement of cardiac output before and after cardiopulmonary bypass in adult patients.