Abstract: Objective  To investigate the application value of non-invasive cardiac system (NICaS) in children with fulminant myocarditis (FM). 
Methods  A total of 39 children with FM were included as the experimental group, and 47 children with pneumonia hospitalized during the same period as the control group. The cardiac index (CI), △CI, Granov Goor index (GGI) and left ventricular ejection fraction (LVEF) of both groups were monitored by NICaS and transthoracic echocardiography (TTE), and the difference in NICaS and TTE and their correlation in experimental group were compared. The experimental group was randomly divided into group A1 (n=21), in which treatment protocols were formulated by NICaS and group A2 (n=18) in which treatment protocols were formulated by TTE. The prognosis of the two groups was compared. 
Results  The CI measured by TTE and NICaS in the experimental group was smaller than that in the control group, and the CI measured by NICaS was smaller than that by TTE in the experimental group, suggesting significant difference (P＜0.05). Pearson correlation analysis showed a significantly positive correlation between the CI measured by NICaS and that by TTE in the experimental group and the control group (r=0.853, 0.751, P＜0.001). Bland-Altman analysis showed good consistency (P=0.079) between the △CI measured by TTE and NICaS (P=0.079), and GGI measured by NICaS was significantly correlated with LVEF by TTE (r=0.727, P＜0.001). Group A1 required less infusion volume, shorter time to achieve negative fluid balance, and had a smaller mortality than group A2, all of which were statistically significant. 
Conclusion  NICaS has good consistency with TTE in terms of CI in children with FM, which can provide simple, non-invasive, reliable and continuous hemodynamic measurements for children with FM, thereby improving the prognosis. 

Key words: myocarditis, non-invasive hemodynamic monitoring, cardiac index