Objective: To evaluate the effect of tramadol on sevoflurane minimum alveolar concentration (MACSEVO) in dogs. It was hypothesized that tramadol would dose-dependently decrease MACSEVO. Study design: Randomized crossover experimental study. Animals: Six healthy, adult female mixed-breed dogs (24.22.6 kg). Methods: Each dog was studied on two occasions with a 7-day washout period. Anesthesia was induced using sevoflurane delivered via a mask. Baseline MAC (MACB) was determined starting 45 minutes after tracheal intubation. A noxious stimulus (50 V, 50 Hz, 10 ms) was applied subcutaneously over the mid-humeral area. If purposeful movement occurred, the end-tidal sevoflurane was increased by 0.1%; otherwise, it was decreased by 0.1%, and the stimulus was re-applied after a 20-minute equilibration. After MACB determination, dogs randomly received a tramadol loading dose of either 1.5 mg kg-1 followed by a continuous rate infusion (CRI) of 1.3 mg kg-1 hour-1 (T1) or 3 mg kg-1 followed by a 2.6 mg kg-1 hour-1 CRI (T2). Post-treatment MAC determination (MACT) began 45 minutes after starting the CRI. Data were analyzed using a mixed model ANOVA to determine the effect of treatment on percentage change in baseline MACSEVO (p<0.05). Results: The MACB values were 1.800.3 and 1.750.2 for T1 and T2, respectively, and did not differ significantly. MACT decreased by 268% for T1 and 3612% for T2. However, there was no statistically significant difference in the decrease between the two treatments. Conclusion and clinical relevance: Tramadol significantly reduced MACSEVO but this was not dose dependent at the doses studied.
- anaesthesia animal health effects animals dogs anesthesia sevoflurane eukaryotes Canis Canidae Fissipeda carnivores mammals vertebrates Chordata animals small mammals
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