Effects of the opioid remifentanil on the arrhythmogenicity of epinephrine in halothane-anesthetized dogs

• Published in: Canadian journal of veterinary research 2008-07, Vol.72 (4), p.362-366
• Main Authors: Garofalo, N.A, Teixeira-Neto, F.J, Schwartz, D.S, Vailati, M. do C.F, Steagall, P.V.M
• Format: Article
• Language: English
• Subjects: Analgesics, Opioid - pharmacology; Anesthesia - veterinary; Anesthetics, Inhalation - administration & dosage; Anesthetics, Inhalation - adverse effects; Animals; Anti-Arrhythmia Agents - therapeutic use; arrhythmia; Arrhythmias, Cardiac - chemically induced; Arrhythmias, Cardiac - drug therapy; Arrhythmias, Cardiac - veterinary; Cross-Over Studies; Dog Diseases - chemically induced; Dog Diseases - drug therapy; Dogs; Electrocardiography - veterinary; epinephrine; Epinephrine - administration & dosage; Female; halothane; Halothane - administration & dosage; Halothane - adverse effects; Heart Rate - drug effects; Infusions, Parenteral - veterinary; narcotics; Piperidines - pharmacology; Random Allocation; Remifentanil
• ISSN: 0830-9000

Opioids may exert a protective effect against ventricular arrhythmias via a vagally mediated mechanism. This study evaluated the effects of the opioid remifentanil on arrhythmogenicity of epinephrine during halothane anesthesia. Eight dogs were assigned to 2 treatments in a randomized crossover design, with 1-week intervals between treatments. Anesthesia was maintained with 1.3% end-tidal halothane in oxygen and mechanical ventilation to maintain eucapnia. A constant rate infusion of remifentanil (0.72 microg/kg/min) was administered throughout the study in the experimental treatment, while control animals received physiologic saline as placebo. The arrhythmogenic dose of epinephrine (ADE), defined as 4 premature ventricular complexes (PVCs) within 15 s, was determined by administering progressively increasing infusion rates of epinephrine (2.5, 5.0, and 10 microg/kg/min), allowing 20 min intervals between each infusion rate. In both treatments, epinephrine infusions induced bradyarrhythmias and atrioventricular conduction disturbances, which were followed by escape beats and PVCs. In the remifentanil treatment, mean +/- s ADE values (11.3 +/- 4.9 microg/kg) did not differ from values observed in control animals (9.9 +/- 6.1 microg/kg). On the basis of the ADE model for assessing the arrhythmogenity of drugs during halothane anesthesia, the present study did not demonstrate a protective effect of remifentanil (0.72 microg/kg/min) against ventricular arrhythmias in dogs.