Research Paper| Volume 43, ISSUE 2, P153-162, March 2016

Evaluation of the non-calibrated pulse contour cardiac output monitor FloTrac/Vigileo against thermodilution in standing horses



      To evaluate the non-calibrated, minimally invasive cardiac output (CO) monitor FloTrac/Vigileo (FloTrac) against thermodilution (TD) CO in standing horses.

      Study design

      Prospective, experimental trial.


      Nine adult horses weighing a median (range) of 535 (470–602) kg.


      Catheters were placed in the right atrium, pulmonary artery and carotid artery under local anaesthesia. CO was measured 147 times by TD and FloTrac and indexed to body weight. Changes in CO were achieved with romifidine or xylazine and dobutamine constant rate infusions. Bland–Altman analysis, concordance and polar plot analysis were used to assess agreement and ability to track changes in CO.


      Mean ± standard deviation COTD of 48 ± 16 mL kg−1 minute−1 (range: 19–93 mLkg−1 minute−1) and mean COFloTrac of 9 ± 3 mLkg−1 minute−1 (range: 5–21 mL kg−1 minute−1) were measured. Low agreement with a large mean bias of 39 mL kg−1 minute−1 and wide limits of agreement of 8–70 mL kg−1 minute−1 were found. The percentage error of 108% and precision of TD of ±18% resulted in an estimated precision of FloTrac of ±106%. Comparison of changes in COFloTrac with changes in COTD gave a concordance rate of 52% in the four-quadrant plot, and a mean polar angle of -11° with radial limits of agreement of ±61 ° in the polar plot. Mean arterial pressure (MAP) and COFloTrac were positively correlated (r = 0.5, p < 0.0001). No correlation of MAP with COTD was observed.

      Conclusions and clinical relevance

      The FloTrac system, originally designed for use in humans, neither measured absolute CO in standing horses accurately nor tracked relative changes in CO measured by TD correctly. The false dependence of COFloTrac on arterial blood pressure further discourages the use of this technique in horses.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Veterinary Anaesthesia and Analgesia
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Ambrisko TD
        • Kabes R
        • Moens Y
        Influence of drugs on the response characteristics of the LiDCO sensor: an in vitro study.
        Br J Anaesth. 2013; 110: 305-310
        • Amory H
        • Linden AS
        • Desmecht DJ
        • et al.
        Technical and methodological requirements for reliable haemodynamic measurements in the unsedated calf.
        Vet Res Commun. 1992; 16: 391-401
        • Bektas RN
        • Kutter AP
        • Hartnack S
        • et al.
        Evaluation of a minimally invasive non-calibrated pulse contour cardiac output monitor (FloTrac/Vigileo) in anaesthetized dogs.
        Vet Anaesth Analg. 2012; 39: 464-471
        • Bland JM
        • Altman DG
        Agreement between methods of measurement with multiple observations per individual.
        J Biopharm Stat. 2007; 17: 571-582
        • Cecconi M
        • Malbrain M
        Cardiac output obtained by pulse pressure analysis: to calibrate or not to calibrate may not be the only question when used properly.
        Intensive Care Med. 2013; 39: 787-789
        • Cecconi M
        • Rhodes A
        • Poloniecki J
        • et al.
        Bench-to-bedside review: the importance of the precision of the reference technique in method comparison studies – with specific reference to the measurement of cardiac output.
        Crit Care. 2009; 13: 201
        • Connors AF
        • Speroff T
        • Dawson NV
        • et al.
        The effectiveness of right heart catheterization in the initial care of critically ill patients. SUPPORT Investigators.
        JAMA. 1996; 276: 889-897
        • Corley KT
        • Donaldson LL
        • Durando MM
        • et al.
        Cardiac output technologies with special reference to the horse.
        J Vet Intern Med. 2003; 17: 262-272
        • Critchley LA
        Pulse contour analysis: is it able to reliably detect changes in cardiac output in the haemodynamically unstable patient.
        Crit Care. 2011; 15: 106
        • Critchley LA
        • Critchley J
        A meta-analysis of studies using bias and precision statistics to compare cardiac output measurement techniques.
        J Clin Monit Comput. 1999; 15: 85-91
        • Critchley LA
        • Lee A
        • Ho AM-H
        A critical review of the ability of continuous cardiac output monitors to measure trends in cardiac output.
        Anesth Analg. 2010; 111: 1180-1192
        • Critchley LA
        • Yang XX
        • Lee A
        Assessment of trending ability of cardiac output monitors by polar plot methodology.
        J Cardiothor Vasc Anesth. 2011; 25: 536-546
        • De Backer D
        • Marx G
        • Tan A
        • et al.
        Arterial pressure-based cardiac output monitoring: a multicenter validation of the third-generation software in septic patients.
        Intensive Care Med. 2011; 37: 233-240
        • Egan JR
        • Festa M
        • Cole AD
        • et al.
        Clinical assessment of cardiac performance in infants and children following cardiac surgery.
        Intensive Care Med. 2005; 31: 568-573
        • Eleftheriadis S
        • Galatoudis Z
        • Didilis V
        • et al.
        Variations in arterial blood pressure are associated with parallel changes in FlowTrac/Vigileo-derived cardiac output measurements: a prospective comparison study.
        Crit Care. 2009; 13: R179
        • Grissom CK
        • Morris AH
        • Lanken PN
        • et al.
        Association of physical examination with pulmonary artery catheter parameters in acute lung injury.
        Crit Care Med. 2009; 37: 2720-2726
        • Gruenewald M
        • Renner J
        • Meybohm P
        • et al.
        Reliability of continuous cardiac output measurement during intra-abdominal hypertension relies on repeated calibrations: an experimental animal study.
        Crit Care. 2008; 12: R132
        • Hadian M
        • Kim HK
        • Severyn DA
        • et al.
        Cross-comparison of cardiac output trending accuracy of LiDCO, PiCCO, FloTrac and pulmonary artery catheters.
        Crit Care. 2010; 14: R212
        • Hallowell GD
        • Corley KT
        Use of lithium dilution and pulse contour analysis cardiac output determination in anaesthetized horses: a clinical evaluation.
        Vet Anaesth Analg. 2005; 32: 201-211
        • Linton RA
        • Young LE
        • Marlin DJ
        • et al.
        Cardiac output measured by lithium dilution, thermodilution, and transesophageal Doppler echocardiography in anesthetized horses.
        Am J Vet Res. 2000; 61: 731-737
        • Marque S
        • Cariou A
        • Chiche J
        • et al.
        Comparison between FloTrac-Vigileo and Bioreactance, a totally noninvasive method for cardiac output monitoring.
        Crit Care. 2009; 13: R73
        • Mayer J
        • Boldt J
        • Poland R
        • et al.
        Continuous arterial pressure waveform-based cardiac output using the FloTrac/Vigileo: a review and meta-analysis.
        J Cardiothorac Vasc Anesth. 2009; 23: 401-406
        • McGee WT
        A simple physiologic algorithm for managing hemodynamics using stroke volume and stroke volume variation: physiologic optimization program.
        J Intensive Care Med. 2009; 24: 352-360
        • Metzelder S
        • Coburn M
        • Fries M
        • et al.
        Performance of cardiac output measurement derived from arterial pressure waveform analysis in patients requiring high-dose vasopressor therapy.
        Br J Anaesth. 2011; 106: 776-784
        • Morgaz Rodriguez J
        • Munoz-Rascon P
        • Navarrete-Calvo R
        • et al.
        Comparison of the cardiopulmonary parameters after induction of anaesthesia with alphaxalone or etomidate in dogs.
        Vet Anaesth Analg. 2012; 39: 357-365
        • Nilsson LB
        • Nilsson JC
        • Skovgaard LT
        • et al.
        Thermodilution cardiac output – are three injections enough?.
        Acta Anaesthesiol Scand. 2004; 48: 1322-1327
        • Ostergaard M
        • Nielsen J
        • Nygaard E
        Pulse contour cardiac output: an evaluation of the FloTrac method.
        Eur J Anaesthesiol. 2009; 26: 484-489
        • Rhodes A
        • Sunderland R
        Arterial pulse power analysis: the LiDCOplus system.
        in: Pinsky MR Payen D Functional Hemodynamic Monitoring. Springer, Germany2005: 183-192
        • Ringer SK
        • Schwarzwald CC
        • Portier KG
        • et al.
        Effects on cardiopulmonary function and oxygen delivery of doses of romifidine and xylazine followed by constant rate infusions in standing horses.
        Vet J. 2013; 195: 228-234
        • Schauvliege S
        • Gasthuys F
        Drugs for cardiovascular support in anesthetized horses.
        Vet Clin North Am Equine Pract. 2013; 29: 19-49
        • Schauvliege S
        • van den Eede A
        • Duchateau L
        • et al.
        Comparison between lithium dilution and pulse contour analysis techniques for cardiac output measurement in isoflurane anaesthetized ponies: influence of different inotropic drugs.
        Vet Anaesth Analg. 2009; 36: 197-208
        • Senn A
        • Button D
        • Zollinger A
        • et al.
        Assessment of cardiac output changes using a modified FloTrac/Vigileo algorithm in cardiac surgery patients.
        Crit Care. 2009; 13: R32
        • Shih A
        Cardiac output monitoring in horses.
        Vet Clin North Am Equine Pract. 2013; 29: 155-167
        • Shih AC
        • Giguere S
        • Sanchez LC
        • et al.
        Determination of cardiac output in anesthetized neonatal foals by use of two pulse wave analysis methods.
        Am J Vet Res. 2009; 70: 334-339
        • Slagt C
        • de Leeuw MA
        • Beute J
        • et al.
        Cardiac output measured by uncalibrated arterial pressure waveform analysis by recently released software version 3.02 versus thermodilution in septic shock.
        J Clin Monit Comput. 2013; 27: 171-177
        • Suga H
        • Nakagawa T
        • Soga Y
        • et al.
        Reinforcement therapy using nitric oxide synthase inhibitors against endotoxin shock in dogs.
        Surg Today. 2006; 36: 811-817
        • Tibballs J
        • Hochmann M
        • Osborne A
        • et al.
        Accuracy of the BoMED NCCOM3 bioimpedance cardiac output monitor during induced hypotension: an experimental study in dogs.
        Anaesth Intensive Care. 1992; 20: 326-331
        • Valverde A
        • Gianotti G
        • Rioja E
        • et al.
        Comparison of cardiac output determined by arterial pulse pressure waveform analysis method (FloTrac/Vigileo) versus lithium dilution method in anesthetized dogs.
        J Vet Emerg Crit Care. 2011; 21: 328-334
        • Young LE
        • Blissitt KJ
        • Bartram DH
        • et al.
        Measurement of cardiac output by transoesophageal Doppler echocardiography in anaesthetized horses: comparison with thermodilution.
        Br J Anaesth. 1996; 77: 773-780