Infusão contínua de duas doses de fentanil associadas à lidocaína e cetamina em fêmeas caninas anestesiadas com sevoflurano e submetidas à ovariohisterectomia eletiva

The aim of this study was to evaluate the cardiorespiratory effects of two doses of fentanyl associated with lidocaine and ketamine in canine females anesthetized with sevoflurane and submitted to elective ovariohysterectomy. 18 animals were randomly assigned to two groups. Group A (GA) animals received a loading dose intravenously of fentanyl 0.0018 mg/kg and those of group B (GB) 0.0036 mg/kg, both associated with lidocaine 3 mg/kg and ketamine 0, 6 mg/kg. Immediately after the loading dose, induction with propofol was realized followed by continuous infusion (CI) of fentanyl at the dose of 0.0018 mg/kg/h for GA and 0.0036 mg/kg/h for GB, both associated to 3 and 0.6 mg/kg/h of lidocaine and ketamine. The anesthesia was maintained with sevoflurane diluted in 100% oxygen at 1.5% by a calibrated vaporizer that was adjusted for the maintenance of the surgical anesthetic plane. The animals were placed in dorsal decubitus position and remained under spontaneous ventilation. Was evaluated the baseline values ​​(T0), after induction (T1) and 5 (T5), 20 (T20) and 35 (T35) minutes of following parameters: heart rate (HR), respiratory rate (f), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean blood pressure (MAP), oxygen saturation in hemoglobin (SatO2), partial carbon dioxide (EtCO2) pressure and expired sevoflurane (EtSevo). Statistical analysis was performed through analysis of variance followed by the Scott-knott test. Differences were considered significant when P < 0.05. HR decreased after 20 minutes of CI and f, SBP, DBP and MAP decreased after anesthetic induction. These differences were not clinically relevant and the values ​​remained within the physiological limit. It can be concluded that the two doses of continuous infusion of fentanyl produced cardiovascular and respiratory stability, besides allowing the reduction of the sevoflurane requirement for elective ovariohysterectomy.