Analysis of the values of parameters of heart rate variability measured in the frequency domain has shown changes of mean values of the absolute values of total power spectrum , mean values of the power of low frequency spectrum and mean values of the power of high power spectrum with reduction of the values of total power spectrum , the power of low frequency spectrum and the power of high frequency spectrum , most pronounced just after induction of anaesthesia with slight increase of the values of total power spectrum and individual components of the spectrum of heart rate variability in the later postinduction period , without statistically significant differences between the groups .