Neuropeptide Y response to tracheal intubation in anaesthetized children: effects of clonidine vs midazolam as premedication.

We have determined if tracheal intubation causes an increase in neuropeptide Y (NPY), a marker of major adrenergic activation, and investigated if rectal premedication with clonidine 2.5 micrograms kg-1 might be capable of attenuating the stress response to tracheal intubation compared with midazolam 300 micrograms kg-1, in 20 paediatric patients (1-9 yr). Prospective randomization was performed in a double-blind manner. After induction of anaesthesia with 1% isoflurane, tracheal intubation was performed, and norepinephrine, NPY concentrations and haemodynamic variables were recorded. Tracheal intubation did not increase NPY plasma concentrations, despite transient increases in norepinephrine concentrations, heart rate and arterial pressure. There was no significant difference between the two groups. We conclude that the adrenergic stress reaction in response to tracheal intubation in children was short-lived and of limited magnitude, as indicated by the lack of NPY release.