МОРФОЛОГІЧНИЙ АНАЛІЗ АРТЕРІЙ М’ЯЗОВОЇ ЧАСТИНИ ДІАФРАГМИ ПІД ЧАС МОДЕЛЮВАННЯ ВНУТРІШНЬОЧЕРЕВНОГО ТИСКУ РІЗНОЇ ТРИВАЛОСТІ

Increased intra-abdominal pressure during the creation of pneumoperitoneum during laparoscopic surgical interventions can cause organ hypoperfusion, and after distension, ischemic-reperfusion injury may occur due to the restoration of blood flow. Intra-abdominal pressure of 12 to 15 mmHg is routinely used during laparoscopy. In patients undergoing laparoscopic surgery, blood flow in the abdominal cavity was significantly reduced, and blood flow to the stomach, small intestine, colon, and liver was also impaired. The aim of the study is to investigate the specifics of the effect of low-pressure pneumoperitoneum of different duration on the morphometric characteristics of small-caliber arteries of the muscular part of the diaphragm. In order to create the experimental model, sexually mature rats aged 6-8 months and weighing (235.0±15.0) grams in the amount of 55 individuals were used. The animals were divided into groups as follows: control group – 10 experimental animals, which were not modeled with any pathology; I main group – 15 animals with simulated pneumoperitoneum for 1 hour; II main group – 15 rats, where pneumoperitoneum lasted 3 hours; III main group – 15 individuals, the experiment lasted 5 hours. The most statistically significant differences in indicators were noted in the III main group, where the created pneumoperitoneum lasted for 5 hours, relative to the measurements obtained in the I main group and with the indicators of the control group. The outer diameter of the costal arteries (36.72 ± 0.27) μm increased by 4.93 %, the arteries of the diaphragm legs (36.81 ± 0.29) μm - by 4.67 % (p <0.001). The inner diameter of small-caliber arteries progressively decreased in the costal part by 16.15 % (p <0.001). In the vessels of the diaphragm legs, its value was lower by 15.87 % (p <0.001). The Wogenworth index increased significantly. In relation to the value of this parameter after 1 hour of pneumoperitoneum, it increased by 13.46 % in the vessels of the costal part (893.60 ± 17.36) and by 13.38 % in the small arteries of the diaphragm legs (896.66 ± 20.27). The thickness of the media increased by 13.38 % in the costal part (13.08 ± 0.34) μm and by 18.85 % in the vessels of the lumbar part (13.25 ± 0.27) μm (p <0.001). Morphometric measurements of endothelial cells at this time showed a decrease in their height in the vessels of the costal part by 4.34 % (p <0.05), and in the diameter of the nuclei by 1.63 % (p <0.05). In the vessels of the lumbar part, these indicators were lower by 4.52 % and 2.26 % (p <0.001), respectively. The relative volume of damaged cells in the vessels of the costal part (4.80 ± 0.03) % was 2.08 times, and in the vessels of the diaphragm legs (5.11 ± 0.05) was 2.07 times higher than the similar indicators of the I main group. In the arteries of the lumbar part, the relative volume of damaged endothelial cells was 6.07 % higher than in the arteries of the costal part. The created intra-abdominal pressure due to the simulation of pneumoperitoneum leads to changes in the parameters of small-caliber arteries in the costal and lumbar parts of the diaphragm, which is characterized by thickening of the vessel wall, reduction of the lumen of the arteries, damage to endothelial cells, endothelial dysfunction, deterioration of the blood supply to the studied parts. The severity of the structural reorganization of the arteries depends on the duration of the created pneumoperitoneum.