The investigators performed a two-stage study to determine the ED50 and the ED95 of intranasal dexmedetomidine in children undergoing transthoracic echocardiography study. In phase 1, 120 participants were randomized in a Dixon-Massey study to describe the minimum local sedative dose. In phase 2, a further 160 participants were randomly allocated to receive sedation with doses in the upper dose-response range to define the ED95
The median effective dose (ED50) and ED95 of intranasal dexmedetomidine as a single bolus have not been described for sedation in children undergoing transthoracic echocardiography (TEE) study. This information is important to compare agents and to determine the most effective sedative dose. The investigators performed a two-stage study to determine the ED50 and the ED95 of intranasal dexmedetomidine to investigate age-related differences in participants undergoing transthoracic echocardiography study.