CLINICAL VALIDATION OF CARDIAC-OUTPUT MEASUREMENTS USING FEMORAL-ARTERY THERMODILUTION WITH DIRECT FICK IN VENTILATED CHILDREN AND INFANTS

Objective: To validate clinically cardiac output (CO) measurements usi ng femoral artery thermodilution in ventilated children and infants by comparison with CO estimated from the Fick equation via a metabolic m onitor. Design: Prospective, comparison study. Setting: Paediatric int ensive care unit of a university hospital. Patients: 24 ventilated inf ants and children, aged 0.3 to 175 months (median age 19 months). Inte rventions: Oxygen consumption measurements were made and averaged over a 5-min period, at the end of which arterial and mixed venous blood s amples were taken and oxygen saturations measured by co-oximetry, with CO being calculated using the Fick equation. Over this 5-min period, five sets of femoral arterial thermodilution (FATD) measurements were made and averaged. One comparison of CO values was made per patient. R esults: Mean Fick CO was 2.55 l/min (range 0.24 to 8.71 l/min) and mea n FATD CO was 2.51 l/min (range 0.28-7.96 l/min). The mean bias was 0. 03 l/min (95 % confidence interval-0.07 to 0.14 l/min), with limits of agreement of -0.45 to 0.52 l/min. When indexed to body surface area, the mean Fick cardiac index became 3.51 l/min per m(2) (1.52-6.98 l/mi n per m(2)) and mean FATD 3.49 l/min per m(2) (1.74-6.84 l/min per m(2 )). The mean bias was 0.02 l/min per m(2) (95 % confidence interval -0 .11 to 0.15 l/min per m(2)) with limits of agreement of 0.57 to 0.61 l /min per m(2). The mean FATD coefficient of variation was 5.8 % (SEM 0 .5 %). Conclusions: FATD compares favourably with Fick derived CO esti mates in infants and children and may represent an advance in haemodyn amic monitoring of critically ill children.