Total intravenous anesthesia (TIVA) is based on multidrug protocols, in which each drug can contribute separately to produce the components of anesthesia. In Veterinary Medicine, data still lacks about TIVA despite an increasingly demand for such protocols has been observed. Therefore, this study was conceived to evaluate the effects of propofol and sufentanil on the cardiopulmonary parameters of dogs premedicated with acepromazine.

For such, twelve adult female mongrel healthy dogs were used. Mean weight was 18.21±2.81 kg. Dogs were given acepromazine (0.05 mg/kg IV) and propofol (5 mg/kg IV). To permit anesthetic maintenance, propofol was continuously infused (0.2 mg/kg/minute) associated to three different doses of sufentanil: (A) 0.25 µg/kg/minute; (B) 0.5 µg/kg/minute and (C) 0.75 µg/kg/minute. Both infusions lasted for 120 minutes. All dogs were anesthetized three times at one-week intervals, each time with a different dose. It was evaluated heart rate (HR); oscillometric systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures; invasive mean arterial pressure (iMAP); respiratory rate (f) and ETCO₂. All parameters were obtained before induction (M1) and each 15 minutes from 5 to 120 minutes after induction (M2 to M8). Data was submitted to ANOVA and Tukey´s test to determine differences.

Heart rate remained within the normal range for dogs in all groups, despite it was observed some reduction until M4 (P<0.05). However, this reduction was greater for group (C), making necessary the use of atropine in 50% of the dogs. For group (B), 33% of dogs had to be given atropine at M4. It was observed that SAP, MAP, DAP and iMAP reduced in all groups (P<0.05) until M8 but remained within normal ranges for canine species. Mechanical ventilation was necessary in all groups and was set at 10 breaths per minute for all animals. However, it had to be instituted at 24.7±8.7; 10.9±5.0 and 6.6±1.5 minutes for groups (A), (B) and (C), respectively. It was seen that ETCO₂ remained within normal range at all moments for all groups.

Results allowed concluding that there is a cardiopulmonary depression in dogs anesthetized with continuous infusion of propofol and sufentanil. Such depression is dependent upon the dose of sufentanil and can be easily controlled by instituting mechanical ventilation in nearly all dogs and providing a chronotropic support in some of them. Once these side effects are controlled, the infusion of propofol and sufentanil can be considered a safe and feasible protocol of TIVA for dogs.