Intravenous clonidine infusion in critically ill children: dose-dependent sedative effects and cardiovascular stability

Clonidine is used for analgesia and sedation in paediatric anaesthesia, but there are no data on its sedative properties and side effects in criticall y ill children. We studied 30 ventilated children aged 10 yr and under to d etermine an effective i.v. dosing range and to assess its cardiovascular ef fects. Twenty non-paralysed, ventilated children were given a background in fusion of midazolam 50 mu g kg(-1) h(-1) combined with a variable clonidine infusion (0.1-2 mu g kg(-1) h(-1)) to maintain optimal sedation. The effec ts of clonidine 1 mu g kg(-1) h(-1) on cardiac index were measured in 10 po stoperative cardiac patients using a reverse Fick method. Dose-dependent se dation was achievable (713 out of 861 h) without cardiovascular side effect s, but an infusion limit of clonidine 1 mu g kg(-1) h(-1) was inadequate in two patients. An increased dose limit of 2 mu g kg(-1) h(-1) combined with midazolam 50 mu g kg(-1) h(-1) achieved satisfactory sedation scores for 6 02 out of a total of 672 h studied with no failures. Clonidine in combinati on with midazolam at 1 mu g kg(-1) h(-1) was not associated with significan t changes in heart rate arterial pressure or cardiac index.