Abstract: Objective To explore and evaluate the feasibility of ultrasound-guided improved dynamic needle tip positioning (DNTP) in infant arterial catheterization.Methods A total of 60 children aged from 1 month to 36 months who were admitted to our hospital from June 2022 to November 2022 and who needed artery puncture and catheterization were selected as subjects.They were randomly divided into two groups,namely DNTP group (D group) and improved DNTP group (G group),with 30 cases in each group.The depth of the radial artery was measured by ultrasound in both groups before operation.In the DNTP group,the depth of the radial artery was less than 2mm as the puncture point.In the improved DNTP group,the shallow radial artery depth was increased to 2-4mm by subcutaneous injection of normal saline under the guidance of ultrasound before puncture.The operation time of the two groups were recorded respectively,and the success rate of the first puncture,the total success rate,the time of the first puncture success,the total puncture time and the incidence of hematoma were compared between the two groups.Results The success rate of first puncture was 90.0% and the total success rate was 96.7% in group G,while 66.7% and 80.0% in group D.There were statistically significant differences between the two groups (P<0.05).The first successful time of group G was (135.2±12.2)s and the total puncture time was (165.3±38.5)s,which was significantly shorter than the first successful time of group D (227.4±23.3)s and the total puncture time of group D (258.3±45.1)s,and the difference was statistically significant (P<0.05).There were 1 case of failure of radial artery puncture caused by local hematoma in group G,and 6 cases of failure of radial artery puncture caused by vasospasm and local hematoma in group D,with statistical significance between the two groups (P<0.05).Ultrasound-guided puncture was successful after changing the puncture site.Conclusion During radial artery catheterization in infants and young children,the ultrasound-guided modified dynamic needle tip positioning technique by subcutaneous injection of normal saline can significantly improve the success rate of puncture,shorten the puncture time and reduce the complications related to puncture.

Key words: artery puncture, dynamic needle tip positioning, infant, depth of radial artery