Cardiac output monitoring during off-pump coronary artery bypass grafting.

OBJECTIVE

To evaluate and compare monitors of cardiac output during repositioning and stabilization of the heart for off-pump coronary artery bypass (OPCAB) surgery.

DESIGN

Prospective, observational, clinical study.

SETTING

University teaching hospital.

PARTICIPANTS

Consecutive patients scheduled to undergo elective OPCAB (n = 19).

INTERVENTIONS

Monitoring, induction, and anesthesia followed a routine protocol for coronary artery bypass patients. This included the use of transesophageal echocardiography (TEE) and pulmonary artery catheter placement.

MEASUREMENTS AND MAIN RESULTS

After positioning and stabilization for OPCAB surgery, the changes in descending aortic flow velocity (VTI) times heart rate (HR) and the mixed venous oxygen saturation (SvO(2)) could be used to predict the changes in thermodilution cardiac output (TDCO) using the following model: deltaTDCO((calc))=-13.15+0.35(deltaVTI*HR)+0.61(deltaSvO(2)) where Delta indicates the percentage change from baseline values. The changes in mean arterial pressure, mean pulmonary artery pressure, and continuous cardiac output did not correlate with the changes in TDCO.

CONCLUSION

The use of the VTIHR, as determined by TEE, in addition to the SvO(2) can strengthen clinical decision making during repositioning and stabilization of the heart during OPCAB. Changes in the VTIHR and SvO(2) can be used as surrogate markers for changes in CO during OPCAB surgery.