Underestimation of cardiac output by thermodilution in patients with tricuspid regurgitation.
BACKGROUND
This study was done to assess the accuracy and reliability of the thermodilution technique in measuring cardiac output in patients with tricuspid regurgitation.


METHODS
In 30 subjects (17 men, 13 women, aged 50 +/- 14 [mean +/- SD] years), cardiac output was measured in close temporal proximity by thermodilution as well as Fick or indocyanine green dye, after which the presence and severity of tricuspid regurgitation were assessed by contrast right ventriculography or pulsed Doppler echocardiography.


RESULTS
In the 13 patients without tricuspid regurgitation, there was excellent agreement between the results of thermodilution and Fick or indocyanine green dye cardiac output determinations (4.95 +/- 1.19 liters/minute by thermodilution, 4.90 +/- 1.11 liters/minute by Fick or indocyanine green dye; NS). In contrast, in the 17 patients with tricuspid regurgitation, the results of thermodilution were consistently lower than those of Fick or indocyanine green dye (4.22 +/- 1.45 liters/minute by thermodilution, 4.99 +/- 1.67 liters/minute by Fick or indocyanine green dye; p less than 0.001).


CONCLUSIONS
Thus, the thermodilution technique of measuring cardiac output is inaccurate in patients with tricuspid regurgitation, yielding results that are consistently lower than the actual outputs.
Cigarroa
R G
RG
Department of Internal Medicine (Cardiovascular Division), University of Texas Southwestern Medical Center, Dallas 75235.
Lange
R A
RA
Williams
R H
RH
Bedotto
J B
JB
Hillis
L D
LD
D000328:Adult; D000368:Aged; D002302:Cardiac Output; D003287:Contrast Media; D004452:Echocardiography; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D007208:Indocyanine Green; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013815:Thermodilution / Q000379:methods; D014262:Tricuspid Valve Insufficiency / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology*
D003287:Contrast Media; D007208:Indocyanine Green