INTRAOPERATIVE EVALUATION OF A CONTINUOUS VERSUS INTERMITTENT BOLUS THERMODILUTION TECHNIQUE OF CARDIAC-OUTPUT MEASUREMENT IN CARDIAC SURGICAL PATIENTS

The purpose of this study was to analyse the clinical agreement betwee n cardiac output measurements, obtained using a newly available contin uous thermodilution technique, and the conventional intermittent bolus technique. Twenty-Sour cardiac surgical patients were intra-operative ly monitored using both techniques. Additionally, two different averag ing modes for the continuous thermodilution technique, either the prev ious 6 min (group 1) or 3 min (group 2) were compared. The mean differ ence between the continuous thermodilution technique and the intermitt ent bolus technique (bias), were calculated at eight selected time poi nts. These ranged from -0.09 to 0.42 litres min(-1) in group 1 and fro m -0.02 to 0.18 litres min(-1) in group 2. There were significant diff erences at any time point between the groups. The relative error betwe en continuous thermodilution and intermittent bolus techniques was <15 % far the majority of measurements and was significantly higher in gro up 1 compared with group 2 just prior to cardiopulmonary bypass. Thus, the continuous thermodilution technique produced a clinically accepta ble level of accuracy compared with the intermittent bolus technique m easurements, especially when using an averaging mode for the previous 3 min.