We investigated the effects of dexmedetomidine infusion on the end-tidal concentration of sevoflurane required for smooth removal of the laryngeal mask airway (LMA) and on the incidence of respiratory complications during postoperative recovery in paediatric patients anaesthetised with sevoflurane. Eighty-seven patients (ASA 1 or 2, aged 3-7 years) were randomly allocated to receive saline (group C), 0.5 µg/kg dexmedetomidine (group D 1), or 1 µg/kg dexmedetomidine (group D 2) after LMA insertion. A predetermined end-tidal sevoflurane concentration for each patient was determined using the Dixon's up-and-down method (starting at 2.2% and step was 0.2%). The LMA was removed after the predetermined concentration had been maintained stable for five minutes. Sevoflurane minimum alveolar concentration for smooth LMA removal and postoperative recovery were assessed. The end-tidal concentration of sevoflurane required for smooth LMA removal in 50% of children (MAC LMA-rM) in group D 2 (0.84±0.15%) was significantly lower than in group D 1 (1.39±0.20%; P=0.003), the latter being significantly lower than in group C (1.73±0.14%; P <0.001). The incidence of breath-holding was significantly lower in group D 2 (3%) than in group C (27%; P=0.009), but comparable between groups D 1 (17%) and C (P=0.385). The incidence of severe coughing was significantly lower in groups D 1 (14%) and D 2 (6%) as compared to group C (39%; P=0.005), but comparable between groups D 1 and D 2 (P=0.323). In conclusion, dexmedetomidine infusion produced a dose-dependent decrease in the end-tidal concentration of sevoflurane required for smooth LMA removal in children and was associated less agitation in the post-anaesthetic care unit.

In some circumstances, a high degree of sedation that results in a child being unconscious at the time of parental separation is desirable. We set out to investigate the efficacy and safety of a rectal premedication regimen designed to produce this increased level of sedation. Sixty-seven children aged two to 24 months were randomised into two groups. Group MK received 4 mg.kg-1 ketamine, 0.5 mg.kg-1 midazolam and 0.02 mg.kg-1 atropine and group MKK received 8 mg.kg-1 ketamine, 0.5 mg.kg-1 midazolam and 0.02 mg.kg-1 atropine per rectum. The sedation score at the time of parental separation 30 minutes after drug administration and the response to intravenous cannulation were evaluated on a fourpoint scale. Respiratory rate, heart rate and arterial oxygen saturation were recorded immediately before parental separation. More patients in group MKK were asleep during separation (62 vs 35%, P <0.05). Fewer patients in group MKK cried during intravenous cannulation (37 vs 68%, P <0.05). Sedation scores were significantly increased at both time points. There was no difference between groups in vital signs at the time of parental separation and no adverse respiratory events occurred during the study period. In cases where a high degree of sedation following premedication in infants and toddlers is desired, the addition of 8 mg.kg-1 ketamine to 0.5 mg.kg-1 midazolam and 0.02 mg.kg-1 atropine administered rectally is more efficacious than 4 mg.kg-1 ketamine.