• Rima N Bektas, Annette P N Kutter, Sonja Hartnack, Rahel S Jud, Manuela Schnyder, José M Matos, and Regula Bettschart-Wolfensberger.
• Section of Anaesthesiology, Equine Department, Vetsuisse Faculty, University of Zurich, Switzerland. rbektas@vetclinics.uzh.ch
• Vet Anaesth Analg. 2012 Sep 1;39(5):464-71.

ObjectiveTo evaluate the accuracy of a new cardiac output monitor (FloTrac/Vigileo), originally designed for humans, in dogs. This pulse contour cardiac output monitoring system cannot be calibrated and measures cardiac output (Q̇t) from a standard arterial catheter.Study DesignProspective experimental trial.AnimalsEight adult Beagle dogs weighing 13.1 (9.8-17.1) kg [median (range)].MethodsAnaesthesia in the dogs was maintained using isoflurane. A pulmonary artery catheter and a metatarsal arterial catheter (22 gauge) were placed. Cardiac output was measured simultaneously 331 times by thermodilution and FloTrac technique. A broad spectrum of Q̇t measurements was achieved through alterations of isoflurane concentration, administration of propofol boluses and dobutamine infusions. Agreement between the methods was quantified with Bland Altman analysis and disagreement was assessed with linear mixed models. Results  Median (10th and 90th percentile) cardiac output as measured with thermodilution was 2.54 (1.47 and 5.15) L minute(-1) and as measured with FloTrac 8.6 (3.9 and 17.3) L minute(-1) . FloTrac measurements were consistently higher with a mean bias of 7 L minute(-1) and limits of agreement of -3.15 to 17.17 L minute(-1) . Difference between the methods was most pronounced in high Q̇t measurements. Linear mixed models showed an estimated difference between the two methods of 8.05 (standard error 1.18) L minute(-1) and a significant interaction between mean arterial pressure and method. Standard deviation (4.45 higher) with the FloTrac method compared to thermodilution was increased.ConclusionCompared to thermodilution measurements, the FloTrac system was influenced to a higher degree by arterial blood pressure, resulting in consistent overestimation of cardiac output.Clinical RelevanceThe FloTrac monitor, whose algorithms were developed based on human data, cannot be used as an alternative for thermodilution in dogs.© 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

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