Three dexmedetomidine constant rate infusion (CRI) in feline ovariectomized patients: sedative and analgesic effects

Three dexmedetomidine constant rate infusion (CRI) regimens in feline ovariectomized patients: sedative and analgesic effects. A.M. Carotenuto, G. Ravasio, L. Borghi, S Boveri, M. Beccaglia, D. Fonda Università degli Studi di Milano, Facoltà di Medicina Veterinaria di Milano, via Celoria 10, 20133 (MI) Italy In cats, few studies have investigated the clinical effect of dexmedetomidine (DMED) CRI during perioperative period. Our aim was to evaluate the analgesic and sedative effects of three rates of DMED CRI in feline patients undergoing ovariectomy, postoperatively monitored for 24 hours. Eighteen female cats were enrolled. After premedication (5 µg kg-1 DMED IM; 0.2 mg kg-1 meloxicam SC), patients were induced with propofol and randomly allocated into three groups (D1-D2-D3) to receive 0.5 (n=6), 1.5 (n=6) and 2.5 (n=6) µg kg-1 h-1 DMED CRI respectively. Anaesthesia was maintained with isoflurane in oxygen and respiration was mechanically controlled using intermittent positive pressure ventilation to maintain normocapnia. Intraoperative hemodynamic parameters and end tidal isoflurane concentration were recorded every 5 minutes. Rescue anaesthesia was provided by means of 0.5 mg kg-1 of propofol in response to acute increases in HR or MAP (20% or more). Postoperatively, sedation, analgesia, muscular relaxation and quality of recovery were evaluated using three postoperative scales (Ansah et al. 2002; Shaffran et al. 2008; Belda et al. 2008). Buprenorphine (10 µg kg-1) was provided as rescue postoperative analgesic drug. Data were analyzed by ANOVA and Kruskal-Wallis test (P<0.05). Intraoperatively, significant differences among groups were not found and any cat did not required rescue propofol, showing stable hemodynamic state. Isoflurane sparing effect of 40% was obtained in D1 and around 48% in D2 and D3. Postoperative analgesia and muscular relaxation showed to be significantly increased in D3 patients than in D1 and D2, while sedative effects resulted to be decreased. Although none patient in three groups required rescue analgesia, D3 showed the most favourable results. DMED infusion, used as part of a balanced anaesthesia, seemed to be safe, useful and effective to obtain adequate intra and postoperative analgesia in feline patients undergoing ovariectomy. References: Arora S (2008) Combining ketamine and propofol (“Ketofol”) for emergency department procedural sedation and analgesia: a review. WestJEM 9, 20-23. Ilkiw JE, Pascoe PJ (2003) Cardiovascular effects of propofol alone and in combination with ketamine for total intravenous anesthesia in cat. AJVR 64, 913-917