Avaliacąõ do estresse transcirúrgico em cadelas submetidas à ovariosalpingohisterectomia sob infusões de fentanil, lidocaína e de cetamina, associada ou naõ à dexmedetomidina

Abstract

Ketamine and dexmedetomidine are analgesic drugs indicated to control surgical pain. This study analyzes the increase in cortisol and blood glucose levels in bitches undergoing continuous infusion of dexmedetomidine and ketamine in ovariosalpingohisterectomy. For that, we compared groups using these drugs with a group using FLK (fentanyl, lidocaine, and ketamine) and the control group (without transsurgical analgesia). The experiment included 40 young (3.8 ± 2.8 years) mixed-breed bitches with average body weight of 9.8 ± 2.4 kg. These animals were allocated into 5 groups according to the recommended anesthetic technique: GCO (control group for pain); GFLK (control group for analgesia), undergoing continuous infusion of fentanyl (50 μg/mL), lidocaine (150 mg), and ketamine (30 mg), or FLK diluted in 500 mL of 0.9% saline solution and infused, after fentanyl bolus (5 μg/kg), at a rate of 10 mg/kg/h, equivalent to: 0.03 μg/kg/min of fentanyl associated with 50 μg/kg/min of lidocaine and 10 μg/kg/min of ketamine, about 5 minutes before surgical incision; GCE, undergoing infusion of only ketamine at the time of surgery, at a rate of 10 μg/kg/min, after intravenous administration of this drug at 2 mg/kg; GDEX, undergoing infusion of dexmedetomidine (2 μg/kg diluted in 20 mL of 0.9% NaCl), starting with an infusion of 2 μg/kg for 5 minutes, followed by an infusion rate of 2 μg/kg/h; GDEXCE, which received dexmedetomidine bolus (2 μg/kg) plus ketamine (2 mg/kg diluted in 20 mL of 0.9% NaCl solution), intravenously, over a period of five minutes. Then, the alpha-2 agonist (diluted in 20 mL of 0.9% NaCl) was infused at a rate of 2 μg/kg/h, and ketamine was continuously infused at 10 μg/kg/min. The results showed a significant reduction of cortisol levels of animals in the GDEXCE group in comparison to the animals in the GCO group at moment 5 (M5). However, cortisol and blood glucose values after extubation were influenced by the action of drugs. Thus, cortisol and blood glucose are not considered effective parameters for assessing transsurgical stress in bitches submitted to ovariosalpingohisterectomy and anesthetized with dexmedetomidine plus ketamine. Considering hemodynamic and behavioral parameters, dexmedetomidine associated with ketamine reduced the surgical stress of animals in the GDEXCE group.