The effectiveness of the use of various options for drainage of the abdominal cavity in creating a model of chronic peritonitis and the determination of indicators of total peritoneal fibrosis

Abstract

For the early diagnosis and prognosis of chronic peritonitis, today there is an urgent need to create an optimal model of chronic peritonitis, to determine the indicators and rates of progression of peritoneal fibrosis.

The aim is to evaluate the effectiveness of using different options for drainage of the abdominal cavity when creating a model of chronic peritonitis and determining the indicators of the formation of total peritoneal fibrosis in the dynamics of peritonitis.

Materials and methods. In the experiment on 60 rats aged 90 days, weighing 220–250 g, chronic peritonitis was simulated by intraperitoneal injection of living cultures of E. coli bacteria and 10 % of fecal suspension (0.5 ml per 100 g of animal weight) through the drainage, as well different options for setting abdominal drainage for peritoneal lavage with an antiseptic were used. In group 1 in 20 rats, drainage was inserted under visual control through a laboratory wound and fixed to the parietal peritoneum on the right flank; in group 2 in 20 rats, the drainage was inserted under visual control through the laboratory wound and fixed to the parietal peritoneum on the right flank; in group 3 in 20 rats, blind insertion of abdominal drainage by trocar was performed. After 12 and 24 hours, the abdominal cavity was flushed three times with 0.9 % NaCl solution and 50 % betadine solution. All rats were injected with 5 ml of mesogel to prevent the formation of adhesions and ensure the functioning of drains, and on the 2^nd day 10 % fecal suspension was administered (0.5 ml per 100 g of animal weight). After 12, 24 hours, 5 and 12 days of the experiment, the peritoneal inflammatory process was monitored taking into account blood leukocytosis. To evaluate the effectiveness of various abdominal drainage options, on the 5^th, 7^th, 14^th, 30^th, and 60^th days, the cytological profile of the washes from the peritoneum of rats, the lethality of animals, the number of festering wounds and the drainage migration were determined.

Results. It has been established that a model of chronic peritonitis with the support of chronic inflammation and the development of peritoneal fibrosis was created only by inserting abdominal drainage under visual control through counteraperture on the back of the surface with its fixation along the right flank to the parietal peritoneum. In these animals, stable long-term leukocytosis was achieved in the range of 10.2–13.3 × 10⁹/l, the cytological profile of the peritoneum washes was characterized by a significant increase (P ˂ 0.05) in the number of mitoses in mesotheliocytes against the background of their relatively stable number. On the 60^th day of the experiment, the histological examination determined the loss of the integumentary mesothelium, abundant overlap of connective tissue fibers was observed on the thickened basement membrane of the peritoneum; in the washes from the peritoneum, the number of mesotheliocytes inversely correlated with the degree of fibrosis following the increase in the number of fibrocytes in 1 mm³ (r = -0.98, P < 0.05).

Conclusions. In late stages of experimental chronic peritonitis with the insertion of drainage of the abdominal cavity through conteraperture on the dorsal surface and fixation of its right flank to the parietal peritoneum in rats, persistent blood leukocytosis occurs within 10.2 × 10⁹/l, in the washes from the peritoneum there is a decrease in the number of mitoses in mesotheliocytes and an increase in the number of fibrocytes, which allows us to consider these parameters as indicators of the development of diffuse peritoneal fibrosis.