British journal of anaesthesia
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Clinical Trial
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 critically ill children. We studied 30 ventilated children aged 10 yr and under to determine an effective i.v. dosing range and to assess its cardiovascular effects. Twenty non-paralysed, ventilated children were given a background infusion of midazolam 50 micrograms kg-1 h-1 combined with a variable clonidine infusion (0.1-2 micrograms kg-1 h-1) to maintain optimal sedation. ⋯ Dose-dependent sedation was achievable (713 out of 861 h) without cardiovascular side effects, but an infusion limit of clonidine 1 microgram kg-1 h-1 was inadequate in two patients. An increased dose limit of 2 micrograms kg-1 h-1 combined with midazolam 50 micrograms kg-1 h-1 achieved satisfactory sedation scores for 602 out of a total of 672 h studied with no failures. Clonidine in combination with midazolam at 1 microgram kg-1 h-1 was not associated with significant changes in heart rate arterial pressure or cardiac index.
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Bispectral index (BIS) was assessed as a monitor of depth of anaesthesia during fentanyl and midazolam anaesthesia for coronary bypass surgery. In 10 patients given morphine premedication, anaesthesia was induced with a combination of midazolam and fentanyl and thereafter maintained with a continuous infusion of a mixture of midazolam and fentanyl 5 and 50 micrograms kg-1 h-1, respectively. BIS was recorded continuously but not shown to the attending anaesthetist. ⋯ No patient reported explicit or implicit recall. During clinically adequate anaesthesia with midazolam and fentanyl BIS varies considerably. The most likely reason is that BIS is not an accurate measure of the depth of anaesthesia when using this combination of agents.