Clinical Evaluation of Intraoperative Multimodal Analgesia Using Constant Rate Infusion of Morphine-Lidocaine-Ketamine Drug Combination in Dogs Undergoing Hemilaminectomy

Abstract

Anesthetic and cardiorespiratory effects of nitrous oxide-oxygen-sevoflrane (GOS) anesthesia with or without a constant rate infusion (CRI) of morphine (0.2 mg/kg/hr) lidocaine (3 mg/kg/hr) and ketamine (0.6 mg/kg/hr) drug combination (MLK-CRI) were evaluated in 50 dogs undergoing hemilaminectomy. All dogs premedicated with an intravenous midazolam (0.3 mg/kg) and intramuscular morphine (0.3 mg/kg) and anesthetized with an intravenous propofol (6 mg/kg). Surgical depth of anesthesia was maintained by GOS with (n=25) or without (n=25) MLK-CRI. Total anesthesia time and extubation time were 83 ± 9 and 17 ± 12 minutes in dogs anesthetized with MLK-CRI or 105 ± 20 and 4 ± 3 minutes in dogs anesthetized without MLK-CRI. The end-tidal sevoflurane concentrations during surgery were 1.50-1.85% or 1.95-2.05% in dogs anesthetized by GOS with or without MLK-CRI, respectively. The sevoflurane requirements for maintaining surgical depth of anesthesia was reduced up to approximately 27% without severe cardiovascular suppression in the dogs receiving MLK-CRI. On the other hand, controlled ventilation was indispensable during anesthesia and extubation time was prolonged in the dogs receiving MLK-CRI. In conclusion, MLK-CRI is clinically useful for sparing with anesthetic requirement and preserving cardiac function during anesthesia, however, it should be aware of respiratory suppression and possibility of prolonged recovery in dogs receiving MLK-CRI.