Comparison of Accuracy of Estimation of Cardiac Output by Thermodilution Versus the Fick Method Using Measured Oxygen Uptake

      The thermodilution (TD) method is routinely used for the estimation of cardiac output (Q̇C). However, its accuracy, compared with the gold-standard Fick method, where systemic oxygen uptake (V̇O2) is directly measured, and Q̇C calculated from V̇O2 and the arterio-venous oxygen difference (“direct” Fick), has not been well validated. The present study determined the agreement between TD and Fick methods in consecutive patients who underwent pulmonary artery catheterization for a broad range of clinical conditions. This is a subanalysis of a previous study comparing the indirect versus Fick method based on a prospective, consecutive patient registry of 253 patients who underwent pulmonary artery catheterization for clinical indications at a single center between 1999 and 2005. We included patients that had an estimation of Q̇C both by the Fick method using measured V̇O2 by exhaled gas analyses from timed Douglas bag collections and by TD. Cardiac index was classified as low when ≤2.2 L/min/m2 or normal when >2.2 L/min/m2. The median (25th, 75th percentile) age of the cohort was 59 (50,67) years, and 50% were female. A total of 43.5% had normal left ventricular function by ventriculography, and 25.7% had ischemic heart disease. Median overall Fick and TD Q̇C were 4.4 (3.5, 5.5) and 4.3 (3.7, 5.2) L/min, respectively (p = 0.04). The median absolute percent error between Fick and TD Q̇C was 17.5 (7.7, 28.4)%, with a typical error of 0.88 L/min (95% confidence interval [CI] 0.82 to 0.95). Median absolute percent error was comparable in the low (n = 118) and normal Q̇CI (n = 135) groups (16.9% vs 18.9%, respectively, p = 0.88). typical error was 0.3 (95% CI 0.27 to 0.33) and 0.49 (95% CI 0.45 to 0.55) L/min/m2 in that comparison. Percent error >25% between Fick and TD Q̇C was observed in over 30% of patients. Overall, Fick and TD Q̇C modestly correlated (Rs = 0.64, p <0.001), with a nondirectional error introduced by TD Q̇C [mean bias of 0.21 (−2.2, 2.7) L/min].
      There was poor agreement between TD and the gold-standard Fick method, highlighting the limitations of making clinical decisions based on TD.
      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 American Journal of Cardiology
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Consolazio CF
        • Johnson RE
        • Pecora LJ.
        Physiological measurements. For use in the study of metabolic functions.
        Rep US Army Med Res Nutr Lab Denver. 1959; : 1-416
        • Laszlo G.
        Respiratory measurements of cardiac output: from elegant idea to useful test.
        J Appl Physiol (1985). 2004; 96: 428-437
        • Argueta EE
        • Paniagua D.
        Thermodilution cardiac output: a concept over 250 years in the making.
        Cardiol Rev. 2019; 27: 138-144
        • Ganz W
        • Donoso R
        • Marcus HS
        • Forrester JS
        • Swan HJ.
        A new technique for measurement of cardiac output by thermodilution in man.
        Am J Cardiol. 1971; 27: 392-396
        • Narang N
        • Thibodeau JT
        • Levine BD
        • Gore MO
        • Ayers CR
        • Lange RA
        • Cigarroa JE
        • Turer AT
        • de Lemos JA
        • McGuire DK.
        Inaccuracy of estimated resting oxygen uptake in the clinical setting.
        Circulation. 2014; 129: 203-210
        • Du Bois D
        • Du Bois EF
        A formula to estimate the approximate surface area if height and weight be known.
        Nutrition. 1916; 5: 303-311
        • Firth BG
        • Dehmer GJ
        • Markham RV
        • Jr Willerson JT
        • Hillis LD
        Assessment of vasodilator therapy in patients with severe congestive heart failure: limitations of measurements of left ventricular ejection fraction and volumes.
        Am J Cardiol. 1982; 50: 954-959
        • Dehmer GJ
        • Firth BG
        • Hillis LD.
        Oxygen consumption in adult patients during cardiac catheterization.
        Clin Cardiol. 1982; 5: 436-440
        • Stevenson LW
        • Perloff JK.
        The limited reliability of physical signs for estimating hemodynamics in chronic heart failure.
        JAMA. 1989; 261: 884-888
        • Wolf A
        • Pollman MJ
        • Trindade PT
        • Fowler MB
        • Alderman EL.
        Use of assumed versus measured oxygen consumption for the determination of cardiac output using the Fick principle.
        Cathet Cardiovasc Diagn. 1998; 43: 372-380
        • Hopkins W.
        A New View of Statistics.
        Internet Society for Sport Science. Victoria University, Melbourne, Australia2016
        • Bland JM
        • Altman DG.
        Statistical methods for assessing agreement between two methods of clinical measurement.
        Lancet. 1986; 1: 307-310
        • Nishimura RA
        • Carabello BA.
        Hemodynamics in the cardiac catheterization laboratory of the 21st century.
        Circulation. 2012; 125: 2138-2150
        • Narang N
        • Gore MO
        • Snell PG
        • Ayers CR
        • Lorenzo S
        • Carrick-Ranson G
        • Babb TG
        • Levine BD
        • Khera A
        • de Lemos JA
        • McGuire DK.
        Accuracy of estimating resting oxygen uptake and implications for hemodynamic assessment.
        Am J Cardiol. 2012; 109: 594-598
        • Opotowsky AR
        • Hess E
        • Maron BA
        • Brittain EL
        • Barón AE
        • Maddox TM
        • Alshawabkeh LI
        • Wertheim BM
        • Xu M
        • Assad TR
        • Rich JD
        • Choudhary G
        • Tedford RJ.
        Thermodilution vs estimated Fick cardiac output measurement in clinical practice: an analysis of mortality From the Veterans Affairs clinical assessment, reporting, and tracking (VA CART) program and Vanderbilt University.
        JAMA Cardiol. 2017; 2: 1090-1099
        • Kubo SH
        • Burchenal JE
        • Cody RJ.
        Comparison of Direct Fick and thermodilution cardiac output techniques at high flow rates.
        Am J Cardiol. 1987; 59: 384-386
        • Hillis LD
        • Firth BG
        • Winniford MD.
        Analysis of factors affecting the variability of Fick versus indicator dilution measurements of cardiac output.
        Am J Cardiol. 1985; 56: 764-768
        • Hoeper MM
        • Maier R
        • Tongers J
        • Niedermeyer J
        • Hohlfeld JM
        • Hamm M
        • Fabel H.
        Determination of cardiac output by the Fick method, thermodilution, and acetylene rebreathing in pulmonary hypertension.
        Am J Respir Crit Care Med. 1999; 160: 535-541
        • Balik M
        • Pachl J
        • Hendl J.
        Effect of the degree of tricuspid regurgitation on cardiac output measurements by thermodilution.
        Intensive Care Med. 2002; 28: 1117-1121
        • Cigarroa RG
        • Lange RA
        • Williams RH
        • Bedotto JB
        • Hillis LD.
        Underestimation of cardiac output by thermodilution in patients with tricuspid regurgitation.
        Am J Med. 1989; 86: 417-420
      1. United States Department of Health and Human Services. 2016 Organ Procurement and Transplantation Network. Modify Adult Heart Allocation 2016 2nd Round. Available at: Accessed February 26th, 2021.

        • Ran G
        • Chung K
        • Anderson AS
        • Gibbons RD
        • Narang N
        • Churpek MM
        • Parker WF.
        Between-center variation in high-priority listing status under the new heart allocation policy.
        Am J Transplant. 2021; 21: 3684-3693
        • Hardin EA
        • Stoller D
        • Lawley J
        • Howden EJ
        • Hieda M
        • Pawelczyk J
        • Jarvis S
        • Prisk K
        • Sarma S
        • Levine BD.
        Noninvasive assessment of cardiac output: accuracy and precision of the closed-circuit acetylene rebreathing technique for cardiac output measurement.
        J Am Heart Assoc. 2020; 9e015794