Bispectral Index in Dogs Anesthetized with Isoflurane and a Continuous Infusion Rate of Morphine-Lidocaine-Ketamine or Fentanyl-Lidocaine-Ketamine
World Small Animal Veterinary Association World Congress Proceedings, 2008
Emílio de Almeida Belmonte1; Newton Nunes1; Patricia Cristina Ferro Lopes1, DVM, MS; Paula Ferreira da Costa1; Roberto Thiesen1; Juliana Vitti Moro1; Vivian Fernanda Barbosa1; Priscila Andréa Costa dos Santos1; Paula Araceli Borges1; Roberta Carareto2
1Department of Veterinary Medicine and Surgery, College of Agricultural and Veterinary Sciences, São Paulo State University, FCAV/UNESP, Jaboticabal, SP, Brazil; 2College of Veterinary Medicine and Zootecny, Tocantins Federal University, Araguaina, TO, Brazil

The aim of this study was to evaluate the effects of morphine-lidocaine-ketamine (MLK) and of fentanyl-lidocaine-ketamine (FLK) association on bispectral index (BIS) in dogs anesthetized with isoflurane that underwent stifle joint surgery.

Two groups (n=8) of dogs, with mean weight of 20.8 ± 3.6 kg were premedicated with levomepromazine (0.5 mg/kg IV). After 10 minutes, anesthesia was induced with propofol (5 mg/kg IV), and the animals were endotracheally intubated and maintained with isoflurane in a semiclosed-circuit under spontaneous ventilation. BIS electrodes were positioned and the dorsal metatarsal artery was catheterized in order to monitor mean arterial pressure (MAP). Once the anesthetic plane was achieved (BIS = 55-65), initial parameters were measured (T0): BIS, cardiac rate (HR), MAP, respiratory rate (f), end-tidal carbon dioxide (EtCO2) and end-tidal isoflurane in V% (EtISO). Right after, MLK (morphine: 3.33 µg/kg/min; lidocaine: 50 µg/kg/min; ketamine: 10 µg/Kg/min) or FLK (fentanyl: 0.033 µg/kg/min; lidocaine: 50 µg/Kg/min; ketamine: 10 µg/Kg/min), both diluted in saline solution, were started at an infusion rate of 10 mL/kg/h.

Parameters were recorded 15 (T15), 30 (T30), 45 (T45), 60 (T60) and 75 (T75) minutes after the beginning of the infusion. Data were evaluated statistically (P < 0,05). HR maintained stable throughout the procedure in both groups; significant differences were seen among groups in T0, T45, T60 and T75, due to individual variability. MAP, f, EtCO2 and BIS values did not change significantly for MLK or FLK at any time point. Both techniques were feasible in maintaining the anesthetic plane, allowing a reduction of 6.25% in EtISO in the MLK group and of 25% in the FLK group in comparison to the EtISO at T0. Considering the measured parameters, MLK and FLK infusion were safe and do not interfere the BIS monitoring (Figure 1).

Figure 1.
Figure 1.

Mean BIS values of dogs anesthetized with isoflurane and a continuous rate infusion of morphine-lidocaine-ketamine (MLK) or fentanyl-lidocaine-ketamine (FLK).

Speaker Information
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Patricia Cristina Ferro Lopes , DVM, MS
Department of Veterinary Medicine and Surgery, College of Agricultural and Veterinary Sciences
São Paulo State University, FCAV/UNESP
Jaboticabal, São Paolo, Brazil

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