The retrospective study included 40 pediatric patients aged between 2 and 12 years with normal growth and an American Society of Anesthesiology physical status (ASA-PS) 1-2 who were sedated with a combination of midazolam-ketamin or midazolam-propofol for the MRI procedure. Patients that received sedatives other than midazolam-ketamine and midazolam-propofol combinations and patients detected with significant abnormalities based on clinical examination, electrocardiogram (ECG), or laboratory parameters were excluded from the study. The sample size of the patient group was determined based on the sample sizes used in similar studies (Selçuk et al. 2013). To attain a 95% confidence interval, a minimum sample size of 20 subjects was required for each group. Accordingly, a total of 40 consecutive patients who met the inclusion criteria were included in the study. The 40 patients were divided into two groups based on the drug combination used for sedation: (I) midazolam-ketamine (M-K) (n = 20) and (II) midazolam-propofol (M-P) (n = 20).
Magnetic resonance imaging (MRI) was performed using a 1.5T MRI scanner (Philips Achieva, Netherlands) according to standard protocols. All the images were evaluated by a single radiologist. Subjective quality of the scans was evaluated using a three-grade scale: 1 = very good (perfect scanning), 2 = moderate (scan completed), 3 = poor (scan uncompleted).
Sedation was performed by the same anesthesia team in each patient. Before transferring to the MRI room, a venous cannula (B. Braun, Melsungen, Germany) was inserted in a suitable forearm vein. The M-K group received 1.5 mg/kg ketamine (Ketalar, 50 mg/ml, 10 ml; Pfizer, Sandwich, UK) and 0.1 mg/kg midazolam (Dormicum, 1 mg/ml, 5 ml; Deva Holding, Istanbul, Turkey) and the M-P group received 1 mg/kg propofol (Propofol-Lipuro, 10 mg/ml, 20 ml; B. Braun, Melsungen, Germany) and 0.1 mg/kg midazolam (Dormicum, 1 mg/ml, 5 ml; Deva Holding, Istanbul, Turkey) intravenously. Patients were placed in supine position with a roller under their shoulders. Continuous monitoring of vital signs including peripheral capillary oxygen saturation (SpO2), systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) was performed with an MRI-compatible anesthesia monitor. Throughout sedation, oxygen was delivered at 2 L/min with a face mask and continuous end-tidal carbon dioxide monitoring was performed. As the sedation protocols involve risks of respiratory complications when performed with spontaneous breathing, the equipment necessary for emergency resuscitation such as laryngeal mask, endotracheal tubes, masks, airway, pediatric laryngoscope set, sedatives and general anesthesia drugs, and aspirator devices were made available in the MRI room.
Demographical findings, total duration of procedure (including anesthesia and imaging), duration of MRI procedure, MRI scanning quality, family satisfaction (Table 1), and Ramsay Sedation Score (RSS) (Table 2) were recorded for each patient. SpO2, SBP, DBP, and HR were recorded every 5 min. The beginning and end of each procedure were recorded after providing appropriate sedation. After the procedure, the patients were transferred to the post-anesthesia care unit (PACU) and were continuously monitored for nausea and vomiting, agitation, pulse rate, and respiratory status until discharge to the ward. Post-anesthesia recovery was measured using the Aldrete Scoring System which rates sedation on a 0-10 scale according to the patient’s activity, oxygen saturation, consciousness, respiration, and circulation.
Patient data were retrieved from the hospital database and the anesthesia reports of the patients.
All data were analyzed using SPSS 17.0 for Windows (Statistical Package for Social Sciences, SPSS Inc., Chicago, IL, United States). Continuous data were expressed as mean ± standard deviation (SD) and categorical data were expressed as percentages. Continuous variables were compared using Mann-Whitney U test and categorical variables were compared using chi-square test. A p value of <0.05 was considered significant.