This trial assessed the effects of two doses of clonidine compared with placebo 
on the quality and speed of recovery in children premedicated with oral 
midazolam and anaesthetised with sevoflurane for cataract surgery. One hundred 
and twenty American Society of Anesthesiologists physical status I to II 
children (aged one to six years), premedicated with oral midazolam 0.5 mg/kg and 
undergoing elective unilateral cataract surgery with sevoflurane anaesthesia 
were studied. Children were randomised to intravenous clonidine 1 microg/kg 
(group C1, n=39), 2 microg/kg (group C2, n=41) or normal saline (group NS, 
n=40). Clinically successful sub-Tenon local anaesthesia block was required for 
a patient to be included in the analysis. The primary outcome was the incidence 
of postoperative agitation. Postoperative agitation was defined as a Pain 
Discomfort Score of -3 using items 3 to 5 only, which was assessed 15 minutely 
until discharge. Agitation was observed in 11/40 (27.5%) children in the NS 
group compared to 2/39 (5.1%) in group Cl and none in group C2 (P < 0.001). 
Rescue medication to treat severe agitation was required in 5/40 (12.5%) in the 
NS group, 1/39 (2.6%) in group C1 and none in group C2 (P = 0.025). Time to meet 
discharge criteria was significantly shorter in group C1 compared to the other 
two groups (48.4 +/- 14.0 minutes compared to C2 79.5 +/- 12.8 minutes and NS 
73.1 +/- 20.4 minutes, P < 0.001). There were no significant effects on blood 
pressure and heart rate. Intravenous clonidine 1 microg/kg is effective for 
reducing agitation after sevoflurane anaesthesia and midazolam premedication in 
children undergoing cataract surgery. Intravenous clonidine 2 microg/kg was also 
effective and for a longer period, but was associated with a longer time to 
discharge.