Noninvasive monitoring of cardiac output in human neonates and juvenile piglets by inductance cardiography (thoracocardiography)

Abstract

Purpose: Thoracocardiography has been used in adult patients to noninvasively estimate changes in cardiac output (CO) by analysis of ventricular volume curves recorded by an inductive plethysmographic transducer encircling the chest at the level of the heart. The purpose of this study was to investigate the potential of thoracocardiography to monitor cardiac output in human neonates and in a small animal model, the juvenile piglet.

Materials and methods: In 6 human premature neonates weighing 1.0 to 1.6 kg the effect of periodic respiration on CO was studied with thoracocardiography. In 9 piglets weighing 8.5 to 10.2 kg changes in CO were estimated simultaneously by thoracocardiography and thermodilution during fluid loading and rapid atrial pacing.

Results: In human neonates, CO during breathing was 136% to 320% of the corresponding value during apneas. In piglets, CO by thermodilution ranged from 0.25 to 3.26 L/min. The mean difference in 40 paired estimates of relative changes in CO by thoracocardiography and thermodilution was 3%, limits of agreement (bias +/- 2 SD) were +/- 30%.

Conclusions: In neonates, increases in CO during respiratory phases of periodic breathing are consistent with expected cardiorespiratory interactions. Thoracocardiography monitored changes in CO in piglets with acceptable accuracy. Thoracocardiography holds promise for noninvasive monitoring in human neonates but further validation is required.