Summary Reasons for performing study: Lidocaine constant rate infusions (CRIs) are common as an intraoperative adjunct to general anaesthesia, but their influence on quality of recovery has not been thoroughly determined. Objectives: To determine the effects of an intraoperative i.v. CRI of lidocaine on the quality of recovery from isoflurane or sevoflurane anaesthesia in horses undergoing various surgical procedures, using a modified recovery score system. Hypothesis: The administration of intraoperative lidocaine CRI decreases the quality of recovery in horses. Methods: Lidocaine (2 mg/kg bwt bolus followed by 50 μg/kg bwt/min) or saline was administered for the duration of surgery or until 30 mins before the end of surgery under isoflurane (n = 27) and sevoflurane (n = 27). Results: Horses receiving lidocaine until the end of surgery had a significantly higher degree of ataxia and a tendency towards significance for a lower quality of recovery. There was no correlation between lidocaine plasma concentrations at recovery and the quality of recovery. Conclusions: Intraoperative CRI of lidocaine affects the degree of ataxia and may decrease the quality of recovery. Potential relevance: Discontinuing lidocaine CRI 30 mins before the end of surgery is recommended to reduce ataxia during the recovery period.

Objective: This review discusses the different analgesic drugs and routes of administration used in large animals for acute pain management. General guidelines and doses are given to assist in choosing techniques that provide effective analgesia. Etiology: Noxious stimuli are perceived, recognized, and localized by specialized sensory systems located at spinal and supraspinal levels. Diagnosis: Localizing the source of the noxious stimulus as well as understanding the behavioral aspects and physiological changes that result from such insult is important to adequately diagnose and treat pain. Pain assessment is far from being definite and objective; not only are there species differences, but also individual variation. In addition, the behavioral and physiological manifestations vary with the acute or chronic nature of pain. Therapy: Pain management should include (1) selecting drugs that better control the type of pain elicited by the insult; (2) selecting techniques of analgesic drug administration that act on pathways or anatomical locations where the nociceptive information is being processed or originating from; (3) combining analgesic drugs that act on different pain pathways; and (4) provide the best possible comfort for the animal. Prognosis: Providing pain relief improves the animal's well being and outcome; however, interpreting and diagnosing pain remains difficult. Continuing research in pain management will contribute to the evaluation of the pathophysiology of pain, pain assessment, and newer analgesic drugs and techniques. (J Vet Emerg Crit Care 2005; 15(4): 295-307)

Objective: To compare the partial CO 2 rebreathing method (non-invasive cardiac output [NICO]) and the lithium dilution method (lithium dilution cardiac output [LiDCO]) for cardiac output (CO) measurement in anesthetized dogs. Design: Prospective study. Setting: College of Veterinary Medicine, University of Florida. Animals: Six adult dogs (weight range 22-25.4 kg).Interventions: All animals were instrumented for CO determinations using the LiDCO and NICO methods. Direct blood pressure, heart rate, arterial blood gases, end-tidal isoflurane (ETI), and CO 2 concentrations were monitored throughout the study. CO was manipulated with dobutamine and isoflurane to allow for intermediate, low, and high CO determinations in that order using LiDCO and NICO. Measurements and main results: A 1.5% ETI produced the intermediate rate of CO, a constantrate infusion of dobutamine (1-4 mg/kg/min) and 1.1% ETI, the highest rate, and 2.5-3% ETI, the lowest rate. Measurements were obtained in duplicate or triplicate for the LiDCO and continuously for the NICO method after achieving a stable hemodynamic plane for at least 15 minutes at each level of CO, allowing 5 minutes between measurements. Forty-seven comparisons were determined. The correlation coefficient (r) between the 2 methods was 0.888 for all determinations. The mean LiDCO and NICO from 47 measurements were 155.9 AE 78.7 mL/kg/min (range, 49.6-303.2) and 146.6 AE 62.9 mL/kg/min (50-290.3), respectively. The bias between LiDCO and NICO estimations was 9.3 ( À 60.7 to 179.4) mL/kg/min (mean and 95% confidence interval). The mean (mL/kg/min) of the differences of LiDCO-NICO was 1.11 Â NICO. The relative error was 2.4 AE 24.7%. As CO increased, the relative difference between the methods also increased. Conclusions: The NICO is a viable non-invasive method for CO determination in the dog and compares well with the LiDCO. (J Vet Emerg Crit Care 2004; 14(3): 187-195)

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