Effect of a constant rate infusion of ketamine on left ventricular systolic and diastolic function in dogs anesthetized with propofol.

Objective: To evaluate the effect of a constant rate infusion of ketamine on left ventricular systolic and diastolic function in dogs anesthetized with propofol.

Study design: Prospective randomized, blinded clinical study.

Animals: Sixteen healthy dogs.

Methods: Dogs were randomized into two groups, the propofol-ketamine group (GPK) and propofol group (GP), with eight animals each. Anesthesia was induced with propofol and maintained with a constant rate infusion (CRI) of propofol at a rate of 0.8 mg/kg/min. All dogs were mechanically ventilated throughout the study. Thirty-five minutes after anesthesia started, the GPK received a bolus of ketamine (0.5 mg/kg IV, over 2 minutes) followed by the CRI of ketamine at 30 μg/kg/min, while the GP received the same volume of 0.9% NaCl over 2 minutes followed by the CRI of 0.9% NaCl at the same rate. Hemodynamic and echocardiographic variables were recorded 15 min after initiating CRI of propofol (M0), immediately after each treatment bolus (M1), and 20 (M2) and 40 min (M3) after initiating CRI of ketamine or 0.9% NaCl solution in both groups.

Results: Cardiac index, stroke index, and peripheral vascular resistance index were not significantly different between treatments. No significant differences in left ventricular systolic and diastolic functions derived from echocardiographic variables were observed between groups.

Conclusions and clinical relevance: During treatment with CRI of ketamine at the proposed rate, hemodynamic parameters and echocardiographic variables, used to measure left ventricular systolic and diastolic function, were maintained stable in healthy dogs anesthetized with propofol.