The effects of intravenous lidocaine before propofol induction in premedicated dogs

The effects of lidocaine, administered before induction of anaesthesia with propofol, on arterial blood pressure, heart rate, respiratory rate, cough reflex, ease of intubation, extrapyramidal signs and required dose of propofol in healthy premedicated dogs were evaluated.

Twenty-four client-owned dogs were premedicated intramuscularly with 1 µg/kg dexmedetomidine and 0·2 mg/kg methadone, and randomly allocated to receive 2 mg/kg lidocaine (group L) or saline (group P) 120 seconds before induction of anaesthesia with propofol. Heart rate, non-invasive arterial blood pressure and respiratory rate were assessed at pre-established intervals. Quality of intubation, cough reflex and the occurrence of adverse effects were scored according to predefined scales. The total amount of propofol administered was also recorded.

Cardiovascular and respiratory variables changed over time but were not significantly different between treatments. No significant differences between groups were found for the incidence of coughing, quality of intubation, adverse effects and propofol intubation dose.

Intravenous administration of lidocaine 2 mg/kg before propofol induction was not associated with significant cardiovascular and respiratory benefits compared to standard induction and did not result in a propofol dose-sparing effect or improvement of the quality of intubation in dogs premedicated with dexmedetomidine and methadone.