Comparison of bioimpedance versus thermodilution cardiac output during cardiac surgery: Evaluation of a second-generation bioimpedance device

Objective: To compare a second-generation thoracic electrical bioimpedance (TEB) hemodynamic monitoring system with the clinically used pulmonary arte ry catheter thermodilution (TD-PAC) system. Design: Blinded, simultaneous measurements at specified key time points dur ing surgery. Setting: University teaching hospital cardiac surgical operating rooms. Participants: Forty-seven patients undergoing primary elective coronary art ery bypass surgery. Interventions: Timed cardiac output measurements by the rmodilution and continuous monitoring of bioimpedance were performed. Measurements and Main Results: Cardiac index (TEB and TD-PAC) and other hem odynamic parameters were measured at 4 time points: (1) after anesthesia in duction, (2) with the mediastinum open, (3) immediately after cardiopulmona ry bypass, and (4) at the end of the case. Pearson's correlation and Bland- Altman analysis were carried out. Cardiac index by TEB and TD-PAC had an ov erall correlation of r = 0.71 (p < 0.0001). The Bland-Altman statistics sho wed a mean difference of -0.28 L/min/m(2) and precision of 0.67 L/min/m2. T he best correlation was at time 1, and the lowest correlation was at time 4 . Mediastinal opening and cardiopulmonary bypass had little or no effect on the correlation between technologies. Conclusion: TEB reporting of cardiac index during coronary artery surgery g enerally agreed with TD-PAC cardiac index except at the end of the case (ti me 4). Copyright (C) 2001 by W.B. Saunders Company.