Intramuscular ketamine provides better sedation and scan conditions in children undergoing magnetic resonance imaging: A single-blinded observational study

The objectives of this study were to compare the quality of sedation provided by intravenous (i.v.) and intramuscular (im) ketamine for pediatric magnetic resonance imaging (MRI).

This study was a non-randomized, single-blinded, and prospective observational study. After receiving approval from the Institutional Ethics Committee, a total of 108 children aged 2-7 years were divided into two groups, with 54 children in each group. In the i.v. group, children received ketamine at a dose of 1.5 mg/kg intravenously, while in the im group, children received ketamine at a dose of 4 mg/kg intramuscularly. If a Ramsay sedation score of 6 (RSS-6) was not achieved, half of the loading dose of ketamine was repeated. In both groups, rescue propofol boluses of 1 mg/kg intravenously were administered whenever the child moved. The primary outcome measure was the quality of sedation, which was assessed by a blinded radiologist. The time taken to reach RSS-6, the number of rescue propofol boluses, the total time wasted in taking repeat sequences, and the time required to achieve a modified Aldrete score of 9 (MAS-9) were recorded.

The im group demonstrated significantly better sedation quality. In the i.v. group, the time to achieve RSS-6 was significantly shorter, but it required more rescue propofol boluses to maintain sedation. The i.v. group also experienced a notable increase in the total time wasted during repeat sequences. On the other hand, the i.v. group exhibited a shorter time to reach MAS-9 compared to the im group.

The im group showed superior sedation quality when compared to the i.v. group. However, it is important to consider that the im group experienced a longer recovery time.