The relationship of depth of anesthesia with blink reflex in cats

The aim of this study was to evaluate the relationship between the blink reflex and the depth of anesthesia in cats and to evaluate the parameters that can be obtained from the blink reflex in addition to its effect in determining the depth of anesthesia. The study material consisted of 32 cats, 7 females and 25 males, with body weights ranging between 1.8-5 kg (mean, 3.80±0.8 kg), brought to Burdur Mehmet Akif Ersoy University, Faculty of Veterinary Medicine, Department of Surgery for various operative purposes. All cats were premedicated with midazolam 0.1 mg/kg and butorphanol 0.4 mg/kg. Propofol at a dose of 4 mg/kg was administered for induction of anesthesia. Following this, maintenance of anesthesia was achieved with sevoflurane. Anesthesia was maintained at a MAC value of 2.9, which is the end tidal MAC value that provides deep anesthesia for cats. Following the end of the operation, electrical stimulation was given to the supraorbital nerve for each 0.1 for each decreasing MAC value starting from 2.9 end tidal MAC value and blink parameters were recorded from the orbicularis oculi muscle. In this study, the mean latency, amplitude and duration values in sevoflurane anesthesia in cats were revealed. In cats, only two blink responses, R1 and R2, were detected at all MAC values. At the same time, there was a very strong positive correlation between R1 latency and MAC and a moderate positive correlation between R2 latency and MAC. There was a very strong negative correlation between R1 amplitude and MAC and a moderate positive correlation between R2 amplitude and MAC. There was a moderate negative correlation between R1 duration and MAC and a weak negative correlation between R2 duration and MAC. When the relationship between the stages of anesthesia and MAC was compared, R1 amplitude and R2 amplitude were significant only between stage II-awake stages. In all other stages, R1 latency, R2 latency, R1 amplitude, R2 amplitude were not significant. It was revealed that all cats woke up with an average MAC value of 0.43±0.20.