Comparison of thoracic electrical bioimpedance and thermodilution for the measurement of cardiac index in patients with severe sepsis.

Cardiac index was measured using thoracic bioimpedance (CIbi) and thermodilution (CItd) in 19 patients with proven sepsis, undergoing artificial ventilation of the lungs. There was a poor correlation between the techniques (r = 0.36, 242 data sets, regression line CIbi = 0.16 CItd + 2.56 litre min-1 m-2). The overall bias (CItd-CIbi) was 1.69 litre min-1 m-2 with limits of agreement (precision) of +4.17 to -0.79 litre min-1 m-2. In individual patients the bias was from -0.46 to 4.56 litre min-1 m-2 with the limits of agreement from +/- 0.29 to +/- 2.55 litre min-1 m-2 around the bias values. The two techniques cannot be used interchangeably in this group of patients.