[Measuring oxygen consumption in healthy infants and children and infants and children with heart diseases].

Oxygen consumption (VO2) must be known to calculate the hemodynamic parameters by Fick's principle. Often VO2 is not measured directly but calculated by nomograms. An open-system method was used for measuring oxygen consumption continuously in 140 healthy infants and children and 152 with congenital heart disease. The patients with heart disease were divided in three groups: I - with large left-to-right shunt (more than 40%), II - with a small left-to-right shunt, and III - without left-to-right shunt. In group I a significantly higher oxygen consumption was measured. There was also a difference in relation of indexed oxygen consumption to age between group I and all the other children. In a second part we compared two methods for determination of indexed oxygen consumption (VO2) in infants and children: measurement using an open system method estimation by using formulas. In healthy infants estimation showed higher values; but no difference was found in healthy children or those without significant left-to-right shunt. In children with congenital heart disease and large left-to-right shunt measured VO2 was significantly higher than the estimated values. No correlation was found in infants with large left-to-right shunt. But in these cases the exact calculation of the hemodynamic parameters would be of great importance. The results indicate that measurement rather than estimation of VO2 is necessary for calculation of hemodynamic parameters.