Objective:To evaluate the effect of different clear fluid fasting duration on the fluid responsiveness after anesthesia induction in pediatric patients with congenital heart disease.Methods:One hundred pediatric patients with congenital heart disease who underwent elective atrial septal defect or ventricular septal defect correction surgery at Shanghai Children′s Medical Center affiliated to Shanghai Jiao Tong University School of Medicine from December 2023 to February 2024 were selected. They were of either sex, aged 6 months to 3 yr, with a body mass index of 13-19 kg/m 2, and classified as American Society of Anesthesiologists Physical Status classification Ⅱ or Ⅲ. Patients who adhered to the prescribed preoperative clear fluid fasting regimen, with a fasting duration of 6 h or longer before surgery, were included in the long fasting (LF) group, while those who were prescribed multi-dimensional nutritional solution until 2 h before surgery with a solid fasting duration≥6 h were considered for inclusion in the short fasting (SF) group. The diastolic blood pressure (DBP) was recorded immediately before and after liver compression test at pre-induction of anesthesia and immediately before and after liver compression test at post-induction of anesthesia, and the changes in DBP before and after the liver compression test (ΔDBP) were calculated. Positive fluid responsiveness was defined as an increase in ΔDBP ≥ 6.25%. The positive rate of fluid responsiveness before and after anesthesia induction was calculated. Results:Sixty-four patients were finally included, and both LF and SF groups included 32 cases. Before the induction of anesthesia, the positive rate of fluid responsiveness induced by liver compression was 28.1% in LF group and 18.8% in SF group, and the difference was not statistically significant ( P>0.05). However, after the induction of anesthesia, the positive rate of fluid responsiveness induced by liver compression was 56.3% in LF group and 28.0% in SF group, with a statistically significant difference observed ( P<0.05). Compared with the baseline before anesthesia induction, the positive rate of fluid responsiveness was significantly increased in LF group( P<0.05), and no significant change was found in the positive rate of fluid responsiveness in SF group ( P>0.05). Conclusions:The prolonged clear fluid fasting may lead to an increase in the positive rate of fluid responsiveness following anesthesia induction in pediatric patients with congenital heart disease, presenting as a state of hypovolemia.