Resumen de Effect of ketamine on the minimum infusion rate of propofol needed to prevent motor movement in dogs

Rachel A. Reed, M. Reza, Agricola Odoi, Sherry K. Cox, Christine M. Egger, Thomas J. Doherty

• Effect of ketamine on the minimum infusion rate of propofol needed to prevent motor movement in dogs Rachel A. Reed, DVM; M. Reza Seddighi, DVM, PhD; Agricola Odoi, BVM, PhD; Sherry K. Cox, PhD; Christine M. Egger, DVM, MVSc; Thomas J. Doherty, MVB, MSc Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996. (Reed, Seddighi, Doherty); Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996. (Odoi, Cox); Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996. (Egger) Address correspondence to Dr. Reed (rachel.anne.reed@gmail.com).

  OBJECTIVE To determine the minimum infusion rate (MIR) of propofol required to prevent movement in response to a noxious stimulus in dogs anesthetized with propofol alone or propofol in combination with a constant rate infusion (CRI) of ketamine.

  ANIMALS 6 male Beagles.

  PROCEDURES Dogs were anesthetized on 3 occasions, at weekly intervals, with propofol alone (loading dose, 6 mg/kg; initial CRI, 0.45 mg/kg/min), propofol (loading dose, 5 mg/kg; initial CRI, 0.35 mg/kg/min) and a low dose of ketamine (loading dose, 2 mg/kg; CRI, 0.025 mg/kg/min), or propofol (loading dose, 4 mg/kg; initial CRI, 0.3 mg/kg/min) and a high dose of ketamine (loading dose, 3 mg/kg; CRI, 0.05 mg/kg/min). After 60 minutes, the propofol MIR required to prevent movement in response to a noxious electrical stimulus was determined in duplicate.

  RESULTS Least squares mean ± SEM propofol MIRs required to prevent movement in response to the noxious stimulus were 0.76 ± 0.1 mg/kg/min, 0.60 ± 0.1 mg/kg/min, and 0.41 ± 0.1 mg/kg/min when dogs were anesthetized with propofol alone, propofol and low-dose ketamine, and propofol and high-dose ketamine, respectively. There were significant decreases in the propofol MIR required to prevent movement in response to the noxious stimulus when dogs were anesthetized with propofol and low-dose ketamine (27 ± 10%) or with propofol and high-dose ketamine (30 ± 10%).

  CONCLUSIONS AND CLINICAL RELEVANCE Ketamine, at the doses studied, significantly decreased the propofol MIR required to prevent movement in response to a noxious stimulus in dogs.