Characterizing Canine Frontal Electroencephalographic Patterns and Cardiovascular Correlates at Different Anesthetic Levels of Sevoflurane

This study evaluated electroencephalogram [EEG] and cardiovascular correlation of sevoflurane anesthesia in healthy beagle dogs at varying minimum alveolar concentration (MAC) multiples. Processed EEG indices (Patient State Index [PSI], burst suppression ratio [SR], and Spectral Edge Frequency [SEF95], cardiovascular parameters (mean blood pressure [MBP], heart rate [HR]), and responses to noxious (electrical) stimuli were recorded. Deep anesthesia (2.5x MAC) resulted in the lowest PSI and MBP values (13.5 ± 9.9, 42.2 ± 7.4 mmHg, respectively), the highest SR (52.7 ± 35.4%), and dominant burst suppression. Surgical anesthesia (1.5x MAC) was characterized by alpha/low beta waves and the absence of response to noxious stimuli. At 1x MAC (2.1%), PSI and MBP increased (41.9 ± 12.6, 119.9 ± 17.7, respectively) while SR decreased (7.1 ± 13%). A moderate PSI-MBP correlation (ρ = 0.48, <i>p</i> = 0.002) was observed. Recovery was acceptable or smooth in most dogs. These findings suggest that sevoflurane disrupts cortical communication, inducing anesthesia and antinociception and that real-time EEG monitoring may aid in titrating sevoflurane delivery in conjunction with MBP.