• Lénio M Ribeiro, David A Ferreira, Susana Brás, Jose M Gonzalo-Orden, and Luis M Antunes.
• CECAV, Hospital Veterinário do Porto, Porto, Portugal. lenioribeiro@hvp.pt
• Vet Anaesth Analg. 2012 Jan 1;39(1):21-8.

ObjectiveTo evaluate if the cerebral state index (CSI), measured by a Cerebral State Monitor (CSM), can predict depth of anaesthesia as assessed clinically or by estimated propofol plasma concentrations.Study DesignProspective clinical study.AnimalsFourteen mixed breed dogs, weighing 24.5 ± 4.7 kg, scheduled to undergo neutering procedures.MethodsDogs were premedicated with 0.05 mg kg(-1) acepromazine intramuscularly. The CSM and cardiovascular monitoring equipment were attached. Anaesthesia was induced with propofol using a target controlled infusion (TCI) to varying plasma propofol targets (PropCp). Following endotracheal intubation the dogs were ventilated with oxygen. Anaesthetic maintenance was with propofol by TCI. A PropCp of 3 μg dL(-1) was set initially, then PropCps were increased in 1 μg dL(-1) steps to 7, 9 and then 11 μg dL(-1). Each PropCp was held constant for a 5 minute period, at the end of which depth of anaesthesia was classified using a previously evaluated scale of 'planes' based on palpebral and corneal reflexes and eye position. Cerebral state index (CSI), burst suppression (BSR) and electromyogram were measured at these time points. The prediction probability (PK) of these variables, or of the PropCp in predicting depth of anaesthesia was calculated.ResultsThe PKs for predicting anaesthetic planes were 0.74, 0.91, 0.76 and 0.78 for CSI, BSR, EMG and PropCp, respectively. The PKs for PropCp to predict CSI, BSR and EMG were 0.65, 0.71 and 0.65 respectively.Conclusion And Clinical RelevanceThe Cerebral State Monitor was able to detect very deep planes of anaesthesia when BSR occurs, but was not able to distinguish between the intermediate anaesthetic planes likely to be used in clinical anaesthesia.© 2011 The Authors. Veterinary Anaesthesia and Analgesia. © 2011 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

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