[Oxygen consumption by indirect calorimetry and Fick equation in swine: role of cardiac output].
OBJECTIVE
To compare O2 uptake values measured by indirect calorimetry (VO2R) with Fick-derived values (VO2Fick) over a wide range of VO2 in experimental conditions and to analyze the influence of cardiac output (QC) on the difference between VO2R and VO2Fick.


METHODS
Animal study.


METHODS
Nineteen 2.5-month-old, 29.2 +/- 2.8-kg, Large White pigs.


METHODS
A step-by-step decrease in venous return was obtained either by haemorrhage or progressive inferior vena cava and portal veins clamping. Measurements, of 5 to 7 minutes duration included VO2R (Deltatrac), thermodilution QC and arterial and mixed venous blood O2-content. The VO2 values were compared using Bland and Altman's bias analysis. The relationship between QC values and relative error (ER = [VO2R - VO2Fick]/0.5x[VO2R + VO2Fick] was analyzed using a Spearman rank correlation coefficient.


RESULTS
The VO2R and VO2Fick arithmetic mean ranged from 108 to 253 mL.min-1 in 130 measurements with broad limits of agreement between both methods. On average, VO2R values were higher than VO2Fick values by +15 +/- 25 mL.min-1. ER significantly decreased with QC (rs = 0.417; P = 0.0001).


CONCLUSIONS
VO2R values exceed VO2Fick values. This bias does not occur in the low QC range, presumably owing to artifactual over estimation of thermodilution QC.
Service d'anesthésie réanimation chirurgicale, Paris V, groupe hospitalier Cochin, France.
Y
Y
Ozier
H
H
Grosse
F
F
Baudin
L
L
Urbani
A
A
Gomola
C
C
Conseiller
J
J
Cardoso
D000818:Animals; D002153:Calorimetry, Indirect; D002302:Cardiac Output; D008433:Mathematics; D010101:Oxygen Consumption; D013552:Swine