Cardiac output measurement after coronary artery bypass grafting using bolus thermodilution, continuous thermodilution, and whole-body impedance cardiography.

OBJECTIVE

To test the feasibility of continuous cardiac output (CO) monitoring with whole-body impedance cardiography after coronary artery bypass grafting and to compare the values obtained with those measured using the bolus and continuous thermodilution methods.

DESIGN

A prospective study.

SETTING

Intensive care unit in a university hospital.

PATIENTS

Twenty patients after coronary artery bypass grafting.

INTERVENTIONS

CO was measured intermittently using the bolus thermodilution method, and continuously using the continuous thermodilution method, and whole-body impedance cardiography immediately after transfer to the intensive care unit.

MEASUREMENTS AND MAIN RESULTS

Bolus thermodilution CO was measured in triplicate at up to 14 time points overnight. Continuous thermodilution CO and whole-body impedance cardiography CO values were recorded simultaneously. During the study period, the bias in CO values between bolus thermodilution and whole-body impedance cardiography ranged from 0.07 to 1.05 L/min and the precision (standard deviation of differences) ranged from 0.82 to 1.31 L/min. The bias between the bolus and continuous thermodilution methods ranged from 0.06 to 0.58 L/min and the precision from 0.43 to 1.02 L/min. Pulmonary artery temperature and CO level were the major determinants of the bias and precision in both comparisons.

CONCLUSIONS

Agreement between whole-body impedance cardiography and bolus thermodilution is slightly inferior to that between the bolus and continuous thermodilution methods but not to the extent that it hampers the use of whole-body impedance cardiography for the continuous monitoring of CO after coronary artery bypass surgery.