Comparison of indirect calorimetry and thermodilution cardiac output measurement in children.
We validated experimentally the ability of hood indirect calorimetry to measure accurately VO2. For this purpose we compared cardiac output calculated from the Fick equation Q = VO2/(Ca(O2) - CV(O2)), in which VO2 was obtained by hood indirect calorimetry, to thermodilution cardiac output (Qth) measured simultaneously during cardiac catheterization in children (n = 16). Because FI(CO2) is a critical factor in hood indirect calorimetry calculations, we also assessed the consequence of taking into account measured FI(CO2) rather than using the usual standard value of 0.0004. We found a good agreement between Q and Qth whether we used experimentally measured FI(CO2) in ambient air (Qth = 0.89 Q + 0.39, r = 0.941) or standard FI(CO2) (Qth = 0.84 Q + 0.55, r = 0.930). However, VCO2 and R computed from standard FI(CO2) differed significantly (p < 0.001) from values derived from measured FI(CO2). This demonstrates that indirect calorimetry allows reasonable estimates of Q, VO2, VCO2, and R provided that the actual values of FI(CO2) are used.
Capderou
A
A
Hôpital Marie-Lannelongue and Département de Physiologie, Faculté deMedécine Pitié-Salpêtrière, Paris, France.
Douguet
D
D
Losay
J
J
Zelter
M
M
D000293:Adolescent; D002153:Calorimetry, Indirect; D002302:Cardiac Output; D002648:Child; D002675:Child, Preschool; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008955:Models, Cardiovascular; D010101:Oxygen Consumption; D013815:Thermodilution / Q000379:methods