A pilot assessment of the FloTrac cardiac output monitoring system

Abstract

Objective: To compare measurement of cardiac output (CO) by means of the FloTrac CO monitor with the pulmonary artery catheter (PAC).

Design: Prospective observational study.

Setting: Intensive care unit of a tertiary hospital.

Patients: Six post-operative cardiac surgery patients with existing arterial cannulas and PACs.

Interventions: Attachment of the FloTrac CO monitor and transducer to an existing arterial cannula. Simultaneous measurements of CO, indexed to body surface area (cardiac index, CI) by the FloTrac CO monitor and by either a bolus thermodilution or continuous CO PAC. Statistical analysis of observations.

Measurements and results: We performed CO measurements in six patients every 1-4 h after cardiac surgery. Comparison of all measurements showed a limited correlation for CI with the two devices (r (2)=0.1218, bias=0.21, 95% limits of agreement -0.81, 1.23). CI measurements obtained with the intermittent bolus PAC had better correlation with the FloTrac CI values (r (2) = 0.2693, bias=-0.0057, 95% limits of agreement -1.2042, 1.1929) than did those obtained with the continuous CO PAC (r (2)=0.0557, bias=0.2436, 95% limits of agreement -0.7350, 1.2222). When analysed according to heart rhythm, CI values measured during atrial pacing showed the best correlation (r (2)=0.377, bias=-0.0244, 95% limits of agreement -0.5226, 0.5714).

Conclusions: CO measurements obtained using the FloTrac CO monitor show a limited correlation with those acquired using the PAC, relatively wide limits of agreement but no clear bias. Further evaluation is required before this device can be recommended for use in the clinical setting.