The results of the Stewart-Fencl approach for interpretation of acid-base status can vary according to the analyzer used. These differences may have important clinical and research implications..

Many devices are available to assess cardiac output (CO) in critically ill patients and in the operating room. Classical CO monitoring via a pulmonary artery catheter involves continuous cardiac output (CCO) measurement. The second generation of Flotrac/Vigileo TM monitors propose an analysis of peripheral arterial pulse waves to calculate CO (APCO) without calibration. The aim of our study was to compare the CO between the Swan Ganz catheter and the Vigileo TM. In this observational study, nine patients undergoing coronary artery bypass grafting were prospectively included. APCO, mean (CCO) and instantaneous CO (ICO) were measured. Perioperative and postoperative assessments were performed up to 24 hours post-surgery. Measurements were recorded every minute, resulting in the collection of 6492 data pairs. Comparison of APCO and ICO showed a limited bias of-0.1 l/min but an important percentage error of 48%. Corresponding values were-0.1 l/min and 46% for the APCO versus CCO comparison, and 0 and 17% for ICO versus CCO comparison. Large inter-individual variability does exist. During cardiac surgery and after leaving the operating room, Vigileo TM is not clinically equivalent to continuous thermodilution by pulmonary artery catheter. Nevertheless, the connection between CCO and ICO relates the difference between APCO and CCO more to the different algorithms used. Further efforts should be concentrated on assessing the ability of this device to track changes in cardiac output.