Propofol is often used for sedation in children undergoing magnetic resonance imaging. The investigators will perform a chart review of 4 month of activity (about 100 cases) and review the incidence and severity of adverse events of this sedation technique.

Magnetic resonance imaging in children, especially under 6 years of age, is often performed under sedation. Propofol is a common drug used in this settings. In our institution, sedation is most often done by a propofol bolus of 2-5 mg/kg in order to reach a deep level of sedation as defined by Coté et al. If judged necessary by the attending anaesthesiologist, a additional propofol bolus of 0.5-1 mg/kg may be given. For longer lasting exams, the attending anaesthesiologist can chose to use a continuous infusion of propofol. The investigators will review the charts of 4 month of magnetic resonance imaging, which will give us a cohort of about 100 patients. Baseline characteristics, detailed sedation technique used will be recorded. Adverse events defined as:

• Oxygen desaturation measured by transcutaneous oximetry SpO2≤94%
• hypercapnia measure by end-tidal CO2 >45 mm Hg
• movement of the patient

Assuming a non-normal distribution (tested by a Kolmogorov-Smirnov test), variables will be reported as median and interquartile range. Statistical tests will be done by non-parametric tests, Mann Whitney U. Non continuous variables will be analyzed by a Chi-square test.

Inclusion Criteria:

• Pediatric patients scheduled for MRI under sedation by an anaesthesiologist
• Age < 16 years

Exclusion Criteria:

• Age > 16 years
• Sedation performed by a non-anesthesiologist

Pediatric patients under 16 years undergoing magnetic resonance imaging under propofol sedation.