Cardiovascular effects of total intravenous anesthesia using ketamine-medetomidine-propofol drug combination (KMP-TIVA) were determined in 5 Thoroughbred horses undergoing surgery. The horses were anesthetized with intravenous administration (IV) of ketamine (2.5 mg/kg) and midazolam (0.04 mg/kg) following premedication with medetomidne (5
µg/kg, IV) and artificially ventilated. Surgical anesthesia was maintained by controlling propofol infusion rate (initially 0.20 mg/kg/min following an IV loading dose of 0.5 mg/kg) and constant rate infusions of ketamine (1 mg/kg/hr) and medetomidine (1.25
µg/kg/hr). The horses were anesthetized for 175 ± 14 min (range from 160 to 197 min). Propofol infusion rates ranged from 0.13 to 0.17 mg/kg/min, and plasma concentration (Cpl) of propofol ranged from 11.4 to 13.3
µg/m
l during surgery. Cardiovascular measurements during surgery remained within clinically acceptable ranges in the horses (heart rate: 33 to 37 beats/min, mean arterial blood pressure: 111 to 119 mmHg, cardiac index: 48 to 53 m
l/kg/min, stroke volume: 650 to 800 m
l/beat and systemic vascular resistance: 311 to 398 dynes/sec/cm
5). The propofol Cpl declined rapidly after the cessation of propofol infusion and was significantly lower at 10 min (4.5 ± 1.5
µg/m
l), extubation (4.0 ± 1.2
µg/m
l) and standing (2.4 ± 0.9
µg/m
l) compared with the Cpl at the end of propofol administration (11.4 ± 2.7
µg/m
l). All the horses recovered uneventfully and stood at 74 ± 28 min after the cessation of anesthesia. KMP-TIVA provided satisfactory quality and control of anesthesia with minimum cardiovascular depression in horses undergoing surgery.
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