AbstractBackgroundPrecordial Doppler ultrasound technology can be used to confirm correct peripheral intravenous access in children. Changes in precordial Doppler sound from the baseline after injecting normal saline are detected using a correct peripheral intravenous access. However, the location of the precordial Doppler probe has been inconsistent in previous studies. Our study aimed to determine whether the right or left parasternal border is the optimal location for precordial Doppler probe placement.MethodsThis single‐center, prospective interventional study was conducted between July 2021 and January 2022 and included children aged 1–6 years. The Doppler probe was placed under general anesthesia at the most audible site on the right and left parasternal borders of patients. Baseline heartbeat was recorded by the Doppler for 10 s on the right and left parasternal borders. After randomizing the order of the recorded data, two blinded raters separately listened to the data and decided the audibility of the sounds.ResultsA total of 77 patients were enrolled in the study. The proportion of the audible baseline heartbeat was significantly higher on the left parasternal borders than on the right by both rater 1 (96.1%, 22.1%, p < 0.001) and rater 2 (96.1%, 27.3%, p < 0.001). Regarding inter‐rater reproducibility, Cohen's kappa statistics for the left and right parasternal borders were significant (0.65 and 0.79, both p < 0.001).ConclusionsThe baseline heartbeat was more audible on the left parasternal border than on the right parasternal border with acceptably high interrater reproducibility. This is inconsistent with the interpretations of previous reports.