Evaluation of the relationship between baseline autonomic tone and the vagotonic effect of a bolus dose of remifentanil.

Remifentanil stimulates the parasympathetic nervous system, and patients with increased parasympathetic tone may be at greater risk of bradycardia after its administration. We aimed to establish if adult patients with increased baseline parasympathetic tone were at higher risk of bradycardia and hypotension when given a bolus dose of remifentanil. Seventy adults (age 20-60 years and ASA physical status 1 or 2) were given remifentanil 1 μg.kg(-1) . A Holter ECG monitor was used to assess heart rate changes. Heart rate variability in the frequency domain during the 5 min after remifentanil administration was analysed. Multivariate analysis demonstrated that baseline heart rate was the only independent predictor of remifentanil-induced bradycardia [odds ratio (95% CI) 0.877 (0.796-0.966)]. The vagotonic action of remifentanil does not appear to be related to baseline autonomic tone in adult patients.