Clinical validation of a new thermodilution system for the assessment of cardiac output and volumetric parameters (Critical Care)

IntroductionTranspulmonary thermodilution is used to measure cardiac output (CO), global end-diastolic volume (GEDV), and extravascular lung water (EVLW). A system has been introduced (VolumeView/ EV1000TM system, Edwards Lifesciences, Irvine CA, USA) that employs a novel algorithm for the mathematical analysis of the thermodilution curve. Our aim was to evaluate the agreement of this method with the established PiCCOTM method (Pulsion Medical Systems SE, Munich, Germany, clinicaltrials.gov identifier: NCT01405040) Methods: 72 critically ill patients with clinical indication for advanced hemodynamic monitoring were included in this prospective, multicenter, observational study. During a 72 hour observation period, 443 sets of thermodilution measurements were performed with the novel system. These measurements were electronically recorded, converted into an analog resistance signal and then re-analyzed by a PiCCO2TM device (Pulsion Medical Systems SE). Results: For CO, GEDV, and EVLW, the systems showed high correlation (r2=0.981, 0.926 and 0.971, respectively), minimal bias (0.2 l/min, 29.4 ml and 36.8 ml), and low percentage error (9.7%, 11.5% and 12.2%). Changes in CO, GEDV, and EVLW were tracked with high concordance between the two systems, with a traditional concordance for CO, GEDV, and EVLW of 98.5%, 95.1%, and 97.7% and a polar plot concordance of 100%, 99.8% and 99.8% for CO, GEDV, and EVLW. Radial limits of agreement for CO, GEDV and EVLW were 0.31 ml/min, 81 ml and 40 ml. Precision of GEDV measurements was significantly better using the VolumeViewTM algorithm compared to the PiCCOTM algorithm (0.033 (0.03) vs. 0.040 (0.03; median (interquartile range), p=0.000049). Conclusions: For CO, GEDV, and EVLW, agreement of both the individual measurements as well as measurements of change showed interchangeability of the two methods. For the VolumeView method, the higher precision may indicate a more robust GEDV algorithm.Trial registration: clinicaltrials.gov NCT01405040