I. Validity of dichnomatic earpiece densitometry for quantitative studies in children with shunt-free cardiovascular malformations.

Cardiac output was assessed in 16 children without evidence of cardiovascular shunts from simultaneously recorded earpiece and cuvette densitometric tracings. The earpiece set-up was calibrated by the end-tail method. Both instruments gave linear response to dye concentrations used. There was a close correlation between cardiac output figures recorded by the two methods (r equal to 0.95) and no systematic difference occurred. It is concluded that in infants and children earpiece densitometry constitutes a rapid and accurate method for quantitative circulatory studies.