Effects of lidocaine constant rate infusion on sevoflurane requirement, haemodynamic function, and postoperative analgesia in dogs undergoing ovariectomy under opioid-based balanced anaesthesia

"It was investigated whether a lidocaine constant. rate infusion (CRI) reduces sevoflurane (SEVO). requirements, haemodynamic\/respiratory responses. to surgery and post-operative pain when added to. an opioid-based anaesthesia.. Twenty-four dogs scheduled for elective ovariectomy. were randomly assigned to one of 4 groups:. CB, buprenorphine without lidocaine; CF, fentanyl. without lidocaine; LB, buprenorphine and lidocaine;. and LF, receiving fentanyl and lidocaine. Dogs. received IV ketoprofen 1.0 mg kg)1 and IV diazepam. 0.3 mg kg)1 and were anaesthetised with IV. diazepam 0.5 mg kg)1 plus ketamine 5.6 mg kg)1. followed by orotracheal intubation. Anaesthesia. was maintained with SEVO in oxygen\/air (50\/50. ratio). Lidocaine (2 mg kg)1 plus 50 lg kg)1 minute)1. ) or equal saline volume was infused in LB\/LF. and CB\/CF, respectively. After initiation of lidocaine. or saline CRI, IV buprenorphine (0.02 mg kg)1. ) or. fentanyl (4 lg kg)1 plus 8 lg kg)1 hour)1. ) were. administered in CB\/LB and CF\/LF, respectively. The. same anaesthetist adjusted vaporiser settings based. on reflexes and responses to surgery. End-tidal SEVO. (FE¢SEVO), total SEVO exposure ([average FE¢SEVO\/. SEVO MAC] · hours), respiratory rate, PE¢CO2, heart. rate, and blood pressures (invasively measured). were recorded. Behaviours and numerical rating. pain scores (Smith & Yu 2001) were assessed 1. and 2 hours post-extubation. Statistical analysis. included paired and unpaired t-tests, analysis of. variance and Kruskal–Wallis tests.. Average FE¢SEVO was similar between groups. (1.7 ± 0.4, 1.4 ± 0.3, 1.4 ± 0.2, 1.3 ± 0.3% in. CB, LB, CF and LF, respectively). Likewise, Lidocaine. CRI did not significantly alter total SEVO exposure,. haemodynamic and respiratory variables, postoperative. behaviours or pain scores.. In dogs undergoing ovariectomy, supplementing. a buprenorphine- or fentanyl-based anaesthetic technique with lidocaine CRI may not change. quality of anaesthesia in terms of inhalant anaesthetic. dose requirement, haemodynamic and respiratory. functions, and perioperative pain relief."