The efficacy of clonidine for reducing perioperative haemodynamic changes and volatile anaesthetic requirements in children.

Abstract

Oral clonidine given as a premedicant in adults has been shown to reduce intraoperative inhalation anaesthetic requirements and provide perioperative haemodynamic stability. We conducted the current study to ascertain whether or not these beneficial effects of clonidine can be reproduced in children. In a prospective, randomized, double-blind, controlled clinical trial, 60 children (ASA I) aged 5-11 yr, received placebo (control), 2 micrograms kg-1 clonidine, or 4 micrograms kg-1 clonidine orally 105 min before induction of anaesthesia. Anaesthesia was induced with halothane, nitrous oxide in oxygen via mask and maintained with halothane and 60% nitrous oxide in oxygen. The halothane concentration was titrated to the concentration required to maintain haemodynamic stability (defined as 20% of blood pressure (BP) and heart rate (HR)) for maintenance of anaesthesia. The end-tidal concentration of halothane was monitored throughout anaesthesia. On completion of surgery, nitrous oxide and halothane were discontinued. Following confirmation of recovery from anaesthesia and muscle relaxation, the endotracheal tube was removed. Higher inspired concentrations of halothane (%) were required in the control and 2 micrograms kg-1 clonidine-treated groups (mean SD: 1.1 +/- 0.2 and 1.0 +/- 0.2, respectively) than in the 4 micrograms kg-1 clonidine-treated group (0.6 +/- 0.1) for haemodynamic stability (P < 0.05). Clonidine, 4 micrograms kg-1, significantly reduced the intraoperative lability (coefficient of variation) of systolic and diastolic BP and HR compared with the other two regimens. Oral clonidine premedication at a dose of 4 micrograms kg-1 provided intraoperative haemodynamic stability and reduced anaesthetic requirements in children. However, we are unable to extrapolate these observations to younger children and infants.