Measurement of cardiac output by thermodilution in infants and children after open-heart operations.

Five hundred twenty-five measurements of cardiac output were made in 26 infants and children after primary repair of congenital cardiac defects. The Edwards Model 9500 thermodilution output computer was used. Cold indicator was injected into the right atrium; in 405 measurements the signal was sensed in pulmonary artery (PA) and in 120 in left atrium. One hundred seven measurements of output by dye dilution (DD) were made in 9 of the infants. Reproducibility was only slightly less good for thermodilution (ID) with PA sensing than for DD but was considerably worse with left atrial sensing. Outputs measured by TD agreed well with those by DD (r = 0.9065). Precautions necessary for accurate measurements and the advantages of TD in infants are discussed.