CONTINUOUS CARDIAC-OUTPUT MEASUREMENTS IN THE PERIOPERATIVE PERIOD

Management of critically ill patients is based on knowledge of fundame ntal physiologic variables. Automatized and continuous measurement of these variables is preferable. A new system based upon the thermodilut ion method has been developed to measure cardiac output automatically and continuously. We evaluated the system in the potentially unstable perioperative period with possible great and rapid changes in cardiac output. Twenty patients, scheduled for open heart or abdominal aortic aneurysm surgery, were included in the study, which was approved by th e local ethical committee. The patients were monitored up to 30 hours. At random intervals five, iced, bolus thermodilution cardiac output ( BCO) determinations were made and compared to the continuous cardiac o utput measurements (CCO). Two hundred and thirty-one pairs of data wer e obtained. The cardiac outputs ranged from 2.5-14.9 l . min(-1). The absolute bias was 0.31 l . min(-1) (95% limits of agreement -1.4 l . m in(-1) to 2.0 l . min(-1)). The mean relative error was 4.7% with a st andard deviation of the relative error of 15.4%. The linear regression was represented by: CCO=1,1352 . BCO-0.36. The correlation coefficien t R was 0.90 (P<0.001). In conclusion, the CCO measurement technique i s a promising clinical method. The method is straightforward, requires no calibration, is independent of vascular geometry and measures with its limitations volumetric Bow. Finally automatic and continuous pati ent monitoring provides more information and has potential to reveal p reviously undetected haemodynamic events.