Impedance cardiography accurately measures cardiac output during exercise in children with cystic fibrosis.

OBJECTIVES

After validation of impedance cardiography (ICG) in healthy children, this same device was tested in children with cystic fibrosis (CF) to validate its capability of measuring cardiac output (Q) in this population.

DESIGN

Comparative study of ICG vs the indirect Fick (CO2) method.

SETTING

Tertiary care children's teaching hospital.

PATIENTS

Twenty-one CF children with mean FEV1 of 77 +/- 21% predicted.

MEASUREMENTS

ICG results were compared with CO2 rebreathing (RB) measurements of Q with sampling of capillary blood gases at two levels of exercise (0.5 and 1.5 W/kg). ICG measurements were made each minute, and duplicate RB measurements from 6 to 8 min at each workload. Q was regressed against oxygen uptake and results by each method were compared.

RESULTS

Mean bias (QRB-QICG) was -0.09 +/- 0.94 L/min. The largest deviation of QICG from QRB was +33%, and 83% of corresponding QICG values were within +/-20% of QRB result.

CONCLUSIONS

This device gives rapid, accurate, noninvasive Q measurements in children with CF.