CONTINUOUS CARDIAC-OUTPUT MONITORING DURING ADULT LIVER-TRANSPLANTATION - THERMAL FILAMENT TECHNIQUE VERSUS BOLUS THERMODILUTION

Continuous thermodilution (CT) using a pulmonary artery (PA) catheter with a thermal filament has the potential for intraoperative on-line m onitoring of cardiac output. Liver transplantation frequently requires rapid fluid administration and often includes the use of an extracorp oreal veno-venous bypass. To assess the agreement between CT and bolus thermodilution (BT) in such a setting, we conducted a prospective int raoperative study in 14 liver transplant patients. Throughout the oper ation, CT cardiac output was recorded and paired with BT measurements taken every 30 min and whenever indicated for clinical reason. Corresp onding data were assigned to acquisition periods when patients were on or off veno-venous bypass (flow rate 2.5 +/- 0.2 L/min) and were disc riminated by the various range of intravenous infusion rates (<150 mL/ h, 150-1000 mL/h, 1000-2000 mL/h, and 2000-4000 mL/h) and the magnitud e of cardiac output (less than or equal to 7.5 L/min, 7.5- 10.0 L/min, >10.0 L/min). A total of 270 data pairs was obtained and examined by analysis of agreement (mean difference +/- SD), variance, error, and w eighted regression. Trend analysis was performed for significant CT an d BT cardiac output changes, defined as changes greater than 15%. Agre ement of both methods was best at peripheral intravenous fluid infusio n rates less than or equal to 1000 mL/h and BT cardiac output >10 L/mi n (0.0 +/- 0.6 L/min) and was unaffected by veno-venous bypass. Discre pancy was most evident at intravenous fluid infusion rates >2000 mL/h and BT cardiac output less than or equal to 7.5 L/min(2.1 +/- 1.7 L/mi n). Correlation of CT and BT cardiac output was excellent (r = 0.95, P < 0.001) for combined data from all patients. Changes in CT cardiac o utput >15% (n = 116) correctly indicated the direction in 93% of BT ca rdiac output changes and were 74% sensitive and 75% specific for signi ficant BT cardiac output changes. The thermal filament technique enhan ces the usefulness of PA catheterization during liver transplantation but reflects BT cardiac output with clinically acceptable error only a t low peripheral intravenous fluid infusion rates. Implications: Cardi ac output determines organ perfusion. In clinical practice, it is meas ured by intermittent thermodilution using right heart catheterization. This intraoperative study compared the intermittent method with a tec hnique based on continuous thermodilution. The new technique provides logistical advantages and challenges the accuracy of the intermittent method during liver transplantation.