Anaesthesia with midazolam and S-(+)-ketamine in spontaneously breathing paediatric patients during magnetic resonance imaging

We evaluated safety and efficacy of a sedation technique based on rectal an d intravenous S-(+)-ketamine and midazolam to achieve immobilization during Magnetic Resonance Imaging (MRI). Thirty-four paediatric patients were ran domly assigned to undergo either the sedation protocol (study group) or gen eral anaesthesia (control group). Imaging was successfully completed in all children. Children in the study group received a rectal bolus (0.5 mg.kg(- 1) midazolam and 5 mg.kg(-1) S-(+)-ketamine) and required additional i.v. s upplementation (20 +/- 10 mu g.kg(-1).min(-1) S-(+)-ketamine and 4 +/- 2 mu g.kg(-1).min(-1) midazolam), spontaneous ventilation was maintained. Trans ient desaturation occurred once during sedation and four times in the contr ol group (P = 0.34). PECO2 was 5.3 +/- 0.5 kPa (40 +/- 4 mmHg) in the study group and 4.1 +/- 0.6 kPa (31 +/- 5 mmHg) in the control group (P < 0.001) . Induction and discharge times were shorter in the study group (P < 0.001) , recovery times did not differ significantly between the groups. Our study confirms that a combination of rectal and supplemental intravenous S-(+)-k etamine plus midazolam is a safe and useful alternative to general anaesthe sia for MRI in selected paediatric patients.