Comparison of Cardiac Output With LiDCO Rapid and TEE Against Thermodilution Technique in Cardiac Surgery

Measurement of the cardiac output is one of the important hemodynamic monitoring tools in
cardiac surgery. It helps determine the type of medications needed to maintain optimal
hemodynamic status in the entire perioperative period. Thermodilution method using pulmonary
artery catheter is considered has the gold standard for the measurement of cardiac output,
however over the past 10 to 15 years it has been questioned about its safety and efficacy.
There has been a surge in recent years of less invasive devices capable of measuring cardiac
output by various means, including bioimpedance, transpulmonary thermodilution,
transthoracic and transesophageal echocardiography, and arterial waveform analysis.

There is a variety of devices currently available for cardiac output measurement by
arterial-waveform analysis. These devices have been compared to each other, and to the
pulmonary artery catheter as the gold standard. However, the companies manufacturing these
devices have made software upgrades that they believe improves their performance. No studies
have been performed comparing the uncalibrated arterial waveform based cardiac output
measurement device,LiDCORapid since the software upgrades. In addition to baseline cardiac
output measurements, Investigators intend to study the effect of volume loading (by
trendelenburg position), sympathetic stimulus (incision), a vasodilated state (15 minutes
after separation from CPB) and chest closure on cardiac output measured by the three
different techniques.

In addition to cardiac output the investigators would like to measure stroke volume
,Systemic Vascular Resistance, stroke volume variation with LiDCO . The main purpose is to
validate the accuracy of measurements by these two minimally-invasive methods in comparison
with thermodilution method in various hemodynamic states.

Inclusion Criteria:

- Elective cardiac procedures other than those specified in the exclusion criteria

Exclusion Criteria:

- All emergency cardiac procedures, prisoners and pregnant women, patients who are
scheduled for ventricular assist devices and those with severe aortic, mitral and
tricuspid insufficiency will be excluded.