Haemodynamic interactions of medetomidine and the peripheral alpha-2 antagonist MK-467 during step infusions in isoflurane-anaesthetised dogs

摘要

The haemodynamic interactions of a step infusion with medetomidine (MED) and the peripherally acting alpha-2 antagonist MK-467 (MK) were compared with MED infused alone in isoflurane-anaesthetised dogs. Eight purposely-bred Beagles were used in a randomised crossover study. Anaesthesia was induced with propofol intravenously (IV) and maintained with isoflurane in oxygen. Dogs received 1.25 mu g/kg MED as a 1 min loading dose IV, along with a step-down MED infusion at rates of 8.0 mu g/kg/h (step 1: 0-20 min), 5.5 mu g/kg/h (step 2: 20-40 min) and 4.0 mu g/kg/h (step 3: 40-95 min). Five minutes after starting the MED infusion, the dogs received MK-467 in a step-up infusion at rates of 100 mu g/kg/h (step 1: 5-35 min), 200 mu g/kg/h (step 2: 35-65 min) and 500 mu g/kg/h (step 3: 65-95 mm). Heart rate (HR), systolic (SAP) and mean arterial (MAP) blood pressures and arteriovenous oxygen content differences (a-vO(2) diff) were calculated. Plasma drug concentrations were analysed. Repeated-measures general linear mixed models with Bonferroni correction were used for statistical analyses.