Abstract: Background：Implementation research refers to systematically integrating evidencebased practice into clinical scenarios to improve the quality and effectiveness of healthcare services and bridge the gap between evidence and clinical practice. However, this type of research has not received much attention. Objective：To develop implementation strategies of the recommendations for venous access devices (VADs) selection in hospitalized children from Clinical Practice Guideline on Infusion Therapy in Children, to evaluate the impact of evidence implementation on patient outcomes, the evidencebased practice behaviors of healthcare workers, and organization environment changes in the hospital, and to identify conflicts between recommendations and clinical practice in different clinical settings. Design：Implementation study. Methods：We developed strategies to promote evidence implementation at Children's Hospital of Fudan University from four perspectives: dissemination, implementation process, integration, and capacity building. These strategies, along with correspongding individualized action plans, were applied in the VAD selection for children's infusion therapy. The implementation process and outcomes were evaluated from four aspects: reach, effectiveness (or efficacy), adoption, and implementation according to the REAIM framework. Main outcome measures：VAD selection error rate, and compliance of VAD selection among nurses. Results：The implementation period was from May 30, 2022, to October 30, 2022. We enrolled 2,343 patients in the intervention group and 2,309 patients in the control group. （1）Reach: During the implementation period, 4, 652 pediatric patients met the inclusion criteria. Out of these, 2, 343 patients received the implementation strategy and individualized action plan. (2) Effectiveness: Among the hospitalized children in the 10 wards, there was no statistically significant gender difference between the two groups. However, there were significant differences in patient age, emergency admission status, surgical status, and department. After adjusting for age, emergency admission status, surgical status, and department, compared to the control group, the intervention group had a 25% reduction in VAD selection error rate (OR=0.745, 95%CI: 0.6120.906). There was no statistically significant difference in the incidence of extravasation/infiltration between the control and intervention groups (OR=1.070, 95%CI: 0.8221.393). The nurses' knowledge level in VAD selection was significantly higher in the intervention group (83.9±12.4) compared to that of the control group (56.0±13.1). Compliance rate of five audit indicators was 100% before, during, and after implementation, compliance rate of four indicators significantly improved before, during, and after implementation, compliance rate of seven indicators showed no statistically significant difference before, during, and after implementation. (3) Adoption: During the implementation period, all 10 wards selected by cluster random sampling (100%) fully participated in the strategy implementation and adopted all 17 pieces of evidence (100%). Multiple rounds of course training (4 hours each) and practical training (3 hours each) were conducted to help nurses understand the implementation strategies and action plans, and all 214 nurses (100%) completed the training courses. (4) Implementation: The study developed six implementation strategies, achieving an 83.3% completion rate. The costeffectiveness index of peripheral intravenous catheter (PIVC) infusion materials before and after the intervention was 2.1>0, indicating that the intervention led to cost savings. Conclusion：The process evaluation of the guideline recommendations indicated a positive result across the four domains of reach, effectiveness (or efficacy), adoption, and implementation based on the REAIM framework. However, a moderate result was indentified in the compliance evaluation of nurses' VAD selection behavior in the effectiveness domain.

Key words: Children, Infusion therapy, Selection of venous access devices, Implementation evaluation