 |
| The UK Society for Intravenous Anaesthesia |
| Based in the UK - as a resource for Anaesthesia Worldwide |
|
|
|
Annual Scientific Meeting, Belfast; November 2000. Evaluation and optimisation of a Target Controlled Infusion System for administering propofol to dogs as part of a total intravenous anaesthetic technique during dental surgeryT Beths Department of Veterinary Medicine, University of GlasgowIn animal clinical practice, propofol forms the basis for TIVA regimes in the dog. Several manual infusion schemes have been described (Hall and Chambers, 1987; Fonda, 1991; Nolan and Reid, 1993). In common with man, blood levels required for surgery in the dog are variable depending on adjuvant therapy, patient status and procedure, and Nolan and Reid (1993) demonstrated that the blood levels required for identical body surface surgery varied between individual animals. While the use of constant and decreasing rate infusions of propofol have become common, to date, TCI systems have not been developed for use in veterinary anaesthesia. Using published pharmacokinetic parameters for propofol in dogs and the infusion scheme used by Nolan & Reid (1993), Glen (1997) programmed the Diprifusor system for use in the dog, and thereafter we investigated its performance in 16 dogs undergoing routine dental work, by comparing predicted with measured propofol concentrations in venous blood samples. Concurrently, we identified optimum targets for induction and maintenance of anaesthesia. The performance of a TCI system is considered clinically acceptable when the Median Prediction Error (MDPE %), and the Median Absolute Performance Error (MDAPE %), is not greater than ± 10 to 20% and 20 to 30% respectively. Results fell within these limits (MDPE % -3.05, MDAPE % 27.15), indicating that the system performed adequately in the dog. The optimal induction target, in premedicated dog, was 3 m g ml-1, and adequate depth and satisfactory quality of anaesthesia were achieved with maintenance targets of between 2.5 and 4.7 m g ml-1 of propofol. The system was easy to use and although the quality of anaesthesia was adequate for dental work, further studies are warranted to investigate the use of TCI with propofol, in combination with analgesic drugs, for more invasive surgical procedures
References: Hall LW, Chambers JP. (1987) A clinical trial of propofol infusion anaesthesia in dogs. J. Small Anim. Pract. 28, 623-637 Fonda D. (1991) Continuous infusion anaesthesia with propofol in dogs: clinically optimized dosages. Proc. 4th Int. Cong. Vet. Anesth. (J. Vet. Anaesthesia [suppl.])159-161 Nolan A., Reid J. (1993) Pharmacokinetics of propofol administered by infusion in dogs undergoing surgery. British Journal of Anaesthesia 70, 546-551 |
|