There are several agents used for conscious sedation by various routes in children. The aim of this prospective randomised study is to compare the effectiveness of three commonly used sedatives: intranasal ketamine, intranasal midazolam, and oral chloral hydrate for children undergoing transthoracic echocardiography.

Children who were referred to paediatric cardiology due to a heart murmur for transthoracic echocardiography were prospectively randomised into three groups. Seventy-three children received intranasal midazolam (0.2 mg/kg), 72 children received intranasal ketamine (4 mg/kg), and 72 children received oral chloral hydrate (50 mg/kg) for conscious sedation. The effects of three agents were evaluated in terms of intensity, onset, and duration of sedation. Obtaining high-quality transthoracic echocardiography images (i.e. absence of artefacts) were regarded as successful sedation. Side effects due to medications were also noted.

There was no statistical difference in terms of sedation success rates between three groups (95.9, 95.9, and 94.5%, respectively). The median onset of sedation in the midazolam, ketamine, and chloral hydrate was 14 minutes (range 7–65), 34 minutes (range 12–56), and 40 minutes (range 25–57), respectively (p < 0.001 for all). However, the median duration of sedation in study groups was 68 minutes (range 20–75), 55 minutes (range 25–75), and 61 minutes (range 34–78), respectively (p = 0.023, 0.712, and 0.045). Gastrointestinal side effects such as nausea and vomiting were significantly higher in the chloral hydrate group (11.7 versus 0% for midazolam and 2.8% for ketamine, respectively, p = 0.002).

Results of our prospectively randomised study indicate that all three agents provide adequate sedation for successful transthoracic echocardiography. When compared the three sedatives, intranasal midazolam has a more rapid onset of sedation while intranasal ketamine has a shorter duration of sedation. Intranasal ketamine can be used safely with fewer side effects in children undergoing transthoracic echocardiography.