ABOUT INFLUENCE OF HAND COOLING ON THE HEARTBEAT AND CHARACTERISTICS OF ALPHA-RHYTHM

We have conducted a research of the influence of hand cooling on the temperature of intact hand and a research of characteristics of variational heart rate monitoring: pulse, parameters of bar chart of R-R intervals distribution, spectrograms and scattergrams, and parameters of EEG’s alpha-rhythm. Wehave registered the following parameters of R-R intervals distribution histogram: mode (Mo), mode amplitude (AMo), variational range (BP), pressure index (IN); spectrogram parameters: overall power of specter (TP), power of low frequency range ( LF) and high frequency range (HF), LF/HF ratio and sattergram cloud area (S). Time of cooling was 4 minutes and the temperature was from 1 0 to 4 C. We distinguished two groups of test subjects according to dynamics of intact hand temperature: some were stable when cooled, their 0 temperature of intact hand dropped no further than 0.4 C, saw no change or even rose, and others were unstable with their researched temperature dropping 0.50 C or more. We understood that heartbeat dynamics did not change in for both groups, however, we saw differences in heartbeat variability haracteristics We came to a result, that stable group has higher numbers of variational range, scattergram cloud area, higher numbers of overall power of specter and LF/HF ratio. Distribution of alpha-rhythm was characterized by significant asymmetry. As a result of cooling, values of researched objects changed in different directions: average values of BP, TP and S did not change drastically, while LF/HF ratio decreased, which shows an important role of central influences on the heartbeat and increase in parasympathetic influence activity under the cooling. The other - unstable - group had lower results of BP, TP, S and LF/HF ratio before the cooling, and after the influence BP, TP and S increased, while LF/HF ratio did not change. Distribution of alpha-rhythm was characterized by notable symmetry. We concluded that there are two patterns of peripheral thermoregulation under the cooling. Constriction of peripheral vessels helps to keep warmth and to centralize the bloodstream, but lowers the temperature of limbs, which is an adequate adaptation type during continuous low-temperature influence. Extension of peripheral vessels helps limbs to function normally, but increases the loss of warmth; this type of thermoregulation seems to be the most adequate when in need of doing short-term manipulation under cooling.

body temperature, hand cooling, variational heart rate monitoring, scattergram cloud area, overall power of specter, alpha- rhythm asymmetry, LF/HF ratio