Purpose. To assess microcirculation and mechanisms of its regulation in the liver after its extended resection.Materials and methods. 10 Wistar rats of both sexes weighing 180–270 g which had median laparotomy under general anesthesia were taken in the trial. Microcirculation in the liver of rats was assessed with LAKK-02 Laser-Doppler flowmeter (Russia). A light guide for determining microcirculation was placed on the visceral surface of the right liver lobe; parameters of Laser-Doppler flowmetry (LDF-gram) were registered for 7 min. Then, ligatures were sequentially applied to the left lateral and median lobes of the liver followed by their cutting off; then, about 70 % of the organ were removed. After removal of both liver lobes, LDF-gram was recorded again for 7 minutes with a sensor placed on the visceral surface of the right liver lobe. Basic microcirculation parameters were registered before and after extended liver resection.Results. After the extended liver resection, average arithmetic parameters of microcirculation in the liver parenchyma decreased by 11.71 % (p < 0.05), which indicates the decrease in the microvasculature perfusion. At the same time, indicators of standard deviation of the microcirculation index and the coefficient of variation did not change statistically significantly. The median maximum amplitude of neurogenic oscillations after the resection increased by 2.3 points (p < 0.05). The amplitude of myogenic oscillations also increased after resection (p < 0.05); however, the degree of increase was less than that of the neurogenic rhythms. It was found that in 70 % of animals the maximum amplitude of endothelial oscillations increased in the liver microcirculation after the extended resection; however, in general, differences between the average endothelial oscillations before and after the resection were not statistically significant.Conclusion. In the experimental liver resection, the most informative and reliable LDF criteria on ischemia development in the liver stump were average arithmetic microcirculation indices as well as the amplitude of neurogenic and myogenic oscillations. The authors emphasize that the degree of changes in these indices may be a sign of ischemia severity in the liver stump after its resection and may have a prognostic value, although the results obtained require further research.

Bioimpedance parameters of the large omentum after performing extensive liver resection in an experiment were evaluated. The study was performed on 20 Wistar rats that underwent median laparotomy under anesthesia, followed by liver resection with the removal of 70% of the organ. Invasive bioimpedance measurement of the liver and large omentum was performed before and immediately after extensive liver resection on days 3 and 14 after surgery using an original device for measuring the electrical impedance of biological tissues BIM-II at frequencies of 2 and 20 kHz with the calculation of the average impedance values at each frequency and measurement zone. Liver tissue was subjected to histological examination. The minimum values of the impedance of the large omentum were recorded on day 3 after extensive liver resection. By day 14, in both zones of the large omentum, the electrical impedance increased relative to day 3 of the postoperative period and did not differ significantly from the indicators before extensive liver resection. Immediately after extensive liver resection, the bioimpedance index in all animals decreased significantly at a frequency of 2 kHz. On day 3 after surgery, the electrical impedance of the liver parenchyma at a frequency of 2 kHz increased significantly. On day 14, the electrical impedance of the liver parenchyma did not differ from the indicators before extensive resection at frequencies of 2 and 20 kHz. A strong significant correlation was found between the electrical impedance of the large omentum and liver parenchyma. At a frequency of 2 kHz, the correlation coefficient of the liver parenchyma and the proximal part of the large omentum was 0.82 and that of the distal part was 0.87 (p 0.05). A strong correlation was detected at a frequency of 20 kHz, with r = 0.93 and 0.74, respectively, in both parts of the gland. Thus, the electrical impedance of the liver parenchyma by day 3 of the experiment increased compared with values before extensive liver resection, whereas the large omentum decreased. We believe that studying the dynamics of the electrical impedance of the large omentum after extensive liver resection is promising in the development of diagnostic criteria for the severity of liver failure.