Patterns of microcirculation changes in acute systemic cold injury
The aim of the work is to reveal patterns of changes in blood flow fluctuations due to autonomic tone in patients with acute systemic cold injury (ASCI) in hypothermic period. Materials and methods. 45 patients aged 18 to 45 years (3 groups of 15 patients with mild, moderate and severe cold trauma) were examined in the hypothermic period. The control group included 15 healthy volunteers. The subjects studied in the groups did not differ in gender, age and body weight. Microcirculation was assessed in all patients on admission using non-invasive laser doppler flowmetry (LDF). Results. In the study of perfusion and blood flow oscillations, it was established that the PM and σ values were increased in patients with mild degrees of ASCI relative to the control group, decreased in severe ASCI, and were not different from controls in moderate degree of ASCI. The parameters of Kv, A<sub>max</sub> (H), and A<sub>max</sub> (M) in patients with mild and moderate degree of ASCI did not significantly differ from the control group; however, in patients with acute intravascular coagulation, there was a marked increase in these parameters in comparison with the control group and with mild and moderate intensity ASCI. The A<sub>max</sub> (C) index did not show any difference in ASCI of mild and moderate degree relative to the control group, however, its decrease was noted in patients with a severe degree of ASCI compared with the control group and with mild and moderate degree of ASIDC. When studying the vibrational component of sympathetic regulation of blood vessels, it was established that the parameters of the normalized maximum amplitude A<sub>max</sub> (H)/σ and A<sub>max</sub> (M)/σ were decreased in patients with mild degree of hypothermia relative to the control group, increased with severe hypothermia and did not have a statistical difference with controls in moderate degree of ASCI. Conclusion. The hypothermic period of ASCI of mild degree is accompanied by a decrease in the vibrational component of sympathetic regulation of the vessels. In the hypothermic period of the moderate degree of ASCI, there is no pronounced change in the amplitude of the neurogenic regulation of the vessels. Severe degree of ASCI in this period is accompanied by a significant increase in blood flow fluctuations due to sympathetic regulation.