Figure 1 A total of 577 patients were screened. Of these, 351 children diagnosed with cyanotic congenital heart disease (CCHD) who met the inclusion and exclusion criteria were enrolled and randomly allocated to the 2-h fast (control group, 174 patients) or 1-h fast (experimental group, 170 patients) groups. Seven patients were excluded from the final analysis for the following reasons: in the 1-h fast group, the parents of 2 children withdrew consent for their child’s data to be used; and in the 2-h fast group, the parents of 3 children withdrew consent for their child’s data to be used and surgery was cancelled for 2 children.