On the Morphofunctional Adequacy of the Intrinsic Blood Vascular Bed of the Small Intestine in the Pathogenesis of Postoperative Peritonitis upon Elimination of Acute Intestinal Obstruction (Experimental-Clinical Study)

The study is dedicated to investigating the morphofunctional adequacy of the intrinsic blood vascular bed of the small intestine in the context of postoperative peritonitis development upon elimination of acute intestinal obstruction. The research combines experimental and clinical approaches and is aimed at identifying the key links in the pathogenesis of anastomotic insufficiency, which is the primary cause of postoperative peritonitis. Special attention is given to the dynamics of reparative processes and hemodynamic changes in the wall of the small intestine in the zone of enteroenteric anastomosis after operative elimination of strangulating and obturating intestinal obstruction.

Based on the conducted comprehensive experimental and clinical research, a scheme of pathogenetically justified treatment for patients who have undergone surgery to eliminate acute intestinal obstruction has been developed, with optimal therapy durations and dynamic observation periods determined. It has been established that the primary link in the pathogenesis of postoperative peritonitis consists of hemodynamic disturbances in the area of the enteroenteric anastomosis, disruptions of reparative processes in the intestinal wound, and, consequently, anastomotic insufficiency.

In recent years, no significant progress has been achieved in the field of diagnosis and treatment of acute intestinal obstruction (AIO), which accounts for 1.2–14.2% of all emergency surgical interventions (1, 2, 7, 10, 11, 14, 69, 72, 73, 91, 195). Patients with intestinal obstruction constitute up to 3.5% of the total number of patients in surgical wards. Among emergency surgical diseases, the share of acute intestinal obstruction reaches 9.4%. In absolute terms, there is a steady increase in the number of patients with AIO, particularly adhesive, since the development of anesthetic techniques has made it possible to perform more complex and, consequently, more traumatic abdominal operations.

Mortality from acute intestinal obstruction ranges from 10.7% to 64.7% (15, 100, 101, 102, 158, 164, 165, 176, 189). Moreover, an increase in mortality from this pathology is observed. Among elderly and pediatric patients, mortality ranges from 43.7% to 64.7% (10, 11, 12, 26, 27, 61, 110, 134, 135, 136, 137, 173, 174, 210).

Postoperative complications, specifically postoperative peritonitis after elimination of acute intestinal obstruction, have been the subject of many scientific works, and mortality from this particular complication has remained close to 100% as it was before (12, 61, 81). This is explained by a number of objective factors. Early diagnosis of postoperative peritonitis is always difficult because it develops against the background of postoperative intestinal ileus, clinical and laboratory general signs of inflammation (completely ordinary and natural in this situation), and medication therapy including potent anti-inflammatory and analgesic drugs. All this masks the symptoms of postoperative peritonitis development and leads to delayed diagnosis.

In postoperative peritonitis after elimination of AIO, the inflammatory process involves a large area of serous covering of approximately 6.5 square meters of peritoneum. The high absorptive capacity of the peritoneum contributes to a strong resorptive-toxic effect of the infectious process in the peritoneal cavity on the weakened organism, affected by acute intestinal obstruction and the operation to eliminate it. As a rule, such patients relatively quickly develop infectious-toxic shock and multiple organ insufficiency, which accounts for such discouraging mortality statistics (81, 107, 115, 120, 160).

The state of the problem testifies to the relevance of continuing scientific research, at least in two directions: 1) the problem of treatment of acute intestinal obstruction aimed at prevention of postoperative peritonitis; 2) effective diagnosis and therapy of postoperative peritonitis. An attempt to solve these tasks, in our view, can succeed only through detailed study of the processes of origin and development (progression) of postoperative peritonitis.

Most works indicate that the cause of postoperative peritonitis after operative elimination of acute intestinal obstruction and resection of the small intestine, more often than others, is anastomotic insufficiency – from 45.7% to 70% of observations (62, 68, 91, 92, 93, 109, 114, 131, 132, 144, 145, 146, 196, 197, 199).

Another frequent intra-abdominal infectious complication is a peritoneal abscess of "unclear genesis" – 14%. Presumably, the cause of this complication is microabscesses and, consequently, microinsufficiency of the anastomosis, or insufficient sanitation of the peritoneal cavity during the first operation. Suture rejection always occurs in the lumen of the organ and is accompanied by tissue dissolution and formation of microabscesses in the thickness of the anastomosis. Fistulous tracts – both blindly ending and open – most often form in the area of the pars nuda of the intestine. As pneumopressure has shown (97), perforation of the anastomosis most often occurs here.

Since anastomotic insufficiency arises from disruption of the processes of intestinal wound healing, that is, reparative processes, which are closely interrelated with the level of trophic supply of tissues, the study of the mechanism of anastomotic insufficiency should be conducted using morphological research methods and quantitative analysis of the structurally functional state of individual links of the organ's vascular bed, taking into account the temporal factor. Neither in domestic nor in foreign literature have we found research results in which the relationship between disturbances of hemodynamics in the area of the enteroenteric anastomosis after elimination of AIO and the development of postoperative peritonitis has been studied in detail.

The goal of the research: improvement of the results of operative treatment of patients with AIO based on identifying the key links in the pathogenesis of anastomotic insufficiency development after operative elimination of acute intestinal obstruction, and development and use of a pathogenetically justified treatment scheme.

Research tasks:

1. To study experimentally the dynamics of changes in the level of metabolic processes in the walls of the small intestine in the area of enteroenteric anastomosis after operative elimination of acute intestinal obstruction.

2. To study experimentally the dynamics of changes in the hemodynamic vascular bed of the small intestine walls in the area of enteroenteric anastomosis after operative elimination of acute intestinal obstruction.

3. To study the correlation between the level of metabolic processes and morphofunctional changes in the vessels of the hemodynamic vascular bed in the small intestine wall in the area of enteroenteric anastomosis after elimination of acute small intestinal obstruction.

4. To conduct an analysis of clinical observations of patients with acute intestinal obstruction and after its elimination depending on the type, duration of acute intestinal obstruction, and the method of its elimination.

5. Based on the data of experimental and clinical research, to justify additions to the generally accepted treatment tactics and determine optimal therapy durations and dynamic observation periods for patients after surgery to eliminate acute small intestinal obstruction.

The novelty of the research consists in the following:

1. Using a complex of morphological and histochemical research methods, the features of the structure of the hemodynamic vascular bed of the small intestine in the area of enteroenteric anastomosis depending on the type and duration of the preceding acute intestinal obstruction have been studied.

2. Based on a large experimental material, the key links in the pathogenesis of enteroenteric anastomotic insufficiency and postoperative peritonitis after elimination of acute intestinal obstruction have been identified. Using a complex of morphological and histochemical methods, elements of similarity and principal differences in the pathogenesis after elimination of various types of acute intestinal obstruction have been studied.

3. Based on the study of clinical materials and conclusions from the experimental part of the work, in addition to existing algorithms, a scheme of pathogenetically justified treatment for patients who have undergone surgery to eliminate acute intestinal obstruction has been developed, with optimal therapy durations and dynamic observation periods determined for this category of patients.

Practical value of the work:

Based on the conducted comprehensive research, a supplement to the treatment algorithm for patients who have undergone surgery to eliminate acute intestinal obstruction has been developed, with optimal therapy durations and dynamic observation periods determined for this category of patients.

Theses for defense:

1. The main link in the pathogenesis of postoperative peritonitis after elimination of acute intestinal obstruction is hemodynamic disturbances in the area of the enteroenteric anastomosis, disruptions of reparative processes in the intestinal wound, and, consequently, anastomotic insufficiency.

2. Between the level of metabolic processes and morphofunctional changes in the vessels of the hemodynamic vascular bed in the small intestine wall in the anastomosis area, a noticeable direct correlation exists after elimination of strangulating small intestinal obstruction (r=+0.66), and an inverse correlation after elimination of obturating small intestinal obstruction (r=-0.67).

3. The main measures for prevention of postoperative peritonitis during formation of the enteroenteric anastomosis should be directed toward normalization and improvement of hemodynamics in the area of the enteroenteric anastomosis.

Defense of the work:

The materials of the work were reported and discussed at a meeting of the section of military-field surgery of the Surgical Society of Moscow and the Moscow Oblast in December 2003; at a scientific-practical conference of physicians of Russia "Uspensky Readings" in Tver, in December 2006.

Based on the dissertation, 14 scientific works have been published. Volume and structure of the dissertation: