Introduction

The problem of acute intestinal obstruction (AIO) constantly remains a focus of clinicians' attention. This is due to the increasing frequency of intestinal obstruction, the progression of which leads to severe homeostatic disturbances that decisively influence the outcome of the disease, and a relatively high mortality rate. In recent years, certain progress has been achieved, consisting of expanding existing understanding of the mechanisms of emerging disorders in intestinal obstruction and methods for their correction.

In Russia, the incidence of AIO is about 5 cases per 100,000 population, accounting for 3 to 9.4% of admissions to surgical hospitals and, unfortunately, shows no steady tendency to decrease [1-5]. The most frequently diagnosed is adhesive intestinal obstruction (50-80% of cases), less frequently (20-30%) - obstructive obstruction. Of the total number of patients suffering from AIO, 88% have mechanical obstruction and 12% have dynamic (functional) obstruction. The disease is observed predominantly in men (male-to-female ratio is 2:1). AIO occurs in all age groups. It is most often observed between the ages of 30 and 60 years. According to various authors, mortality for this pathology ranges from 5.1 to 8.4%, occupying one of the leading positions among all urgent diseases. Despite the intensive introduction of new medical technologies into practice, mortality in AIO can in some cases reach 15–22%. Postoperative mortality in patients with intestinal obstruction ranges from 5 to 30% [3, 6-11]. The reasons for the current situation are well known and are primarily associated with the diversity of homeostatic disturbances in patients with AIO [1, 12, 13].

Therapeutic tactics and the evaluation of treatment outcomes for obstruction are linked to identifying the stages of the process's development. The phasic course of the disease has been repeatedly indicated in the literature and is currently being confirmed. Eryukhin I. A. et al. (1999) identified the following three stages in the development of the pathological process in intestinal obstruction: Stage I - acute disturbance of intestinal passage; Stage II - acute disorder of intramural intestinal hemocirculation (ischemia); Stage III - peritonitis [1]. New approaches in interpreting pathogenetic processes in AIO are associated with identifying acute intestinal failure syndrome (enteral failure) [12, 14-16], which led Popova I. S. et al. (2008) to consider clinical-diagnostic and treatment problems in acute obstructive intestinal obstruction from the perspective of two syndromes: enteral hypertension syndrome and enteral failure syndrome [17].

Considering the diversity of clinical manifestations of AIO and the multifactorial nature of its pathogenesis, Chernov V. N. et al. (1997) identified 5 stages in the clinical course of acute small bowel obstruction: Stage I - disorder of intramural intestinal hemocirculation, or ischemic stage; Stage II - water-electrolyte disorders; Stage III - peritonitis; Stage IV - multiple organ failure (MOF); Stage V - chronic intestinal failure [18]. Saveliev V. S. et al. (2004) distinguish the following three stages: initial - local manifestations of acute disturbance of intestinal passage; intermediate - apparent well-being, characterized by the development of acute intestinal failure, water-electrolyte disorders, and endotoxemia; late - peritonitis and severe abdominal sepsis, often termed the terminal stage [2].

Undoubtedly, the number of proposed classifications for AIO is significantly larger. Dividing the development of AIO into stages (periods, phases, degrees) is always conditional. The duration and development of each stage for each form of obstruction and even for each patient are subject to individual differences. However, AIO is, first and foremost, a dynamically developing pathological process with its characteristic disturbances of both a specific and general biological nature. Such a diversity of classifications testifies to the complexity of the problem and its insufficient study, especially of various pathogenetic links. Apparently, none of the classifications claim to be universal, since over time our data on the genesis of the disease will be constantly supplemented and refined, and this, in turn, will allow for certain adjustments to be made to the staging of the AIO course and, consequently, to the classification of the disease [1, 18, 19].

Among the multitude of homeostatic disturbances in AIO, a significant place belongs to endointoxication and neurohumoral changes, which are the most labile and actively participate in regulating the functioning of vital body functions, up to multiple organ disturbances, which is one of the main reasons for unsatisfactory treatment results. This problem becomes most acute in the case of delayed surgical intervention, when eliminating the obstruction does not provide the necessary conditions for the patient's recovery [1, 18-20]. Their timely elimination will undoubtedly have a positive impact on the course of the postoperative period and treatment outcomes.

In addition to the basic principles of AIO treatment aimed at eliminating the cause of the disease and correcting dysfunctions of vital organs and systems, the implementation of another principle is required - detoxification of the body. However, despite the large number of various detoxification methods with correction of different homeostatic links, none, unfortunately, can claim universality. Existing research on this matter is highly contradictory and is limited mainly to mentioning the importance of disturbances in the pathogenesis of this pathology [19, 21, 22]. The study of the latter, apparently, will contribute not only to expanding understanding of the pathogenesis of AIO but also, to a certain extent, will create prerequisites for the advisability of using existing and proposed treatment methods.

In this regard, issues of diagnosis and treatment of patients with intestinal obstruction remain relevant. The outlined prerequisites served as the starting point for conducting this study.

Objective: To evaluate the treatment outcomes of patients with acute intestinal obstruction based on the application of an improved set of therapeutic measures.

Materials and methods

During the period 2020–2024, at the clinic of hospital surgery of Yaroslavl State Medical University, based at Clinical Hospital No. 9, 1279 patients with acute intestinal obstruction aged 20 to 90 years were under observation. There were 547 men (42.8%) and 732 women (57.2%). 431 patients (33.7%) were observed under the age of 60; the largest group consisted of 633 people in the 60–75 year age category (49.5%); 215 patients (16.8%) were over 75 years old.

Results and discussion

In 69.8% of cases (893 patients), the causes of mechanical intestinal obstruction were various pathologies of non-tumor genesis. In 386 patients (30.2%), obstructive intestinal obstruction was caused by tumors of the colon and small intestine, varying in location and morphological structure.

The most common cause of non-tumor obstruction was abdominal adhesive disease, diagnosed in 681 patients (76.3%). Strangulated hernia complicated by obstruction was observed in 138 patients (15.4%). Less frequently, acute intestinal obstruction was caused by volvulus (49 patients), knotting (7 patients), and intussusception (5 individuals), totaling 6.8% of cases in this group. In 13 patients (1.5% of cases), the cause of small bowel obstruction was gallstones.

555 patients (43.4%) were hospitalized within 24 hours of disease onset, of which 52 (4.0%) were within 6 hours, and 88 patients (6.9%) within 12 hours. In 56.6% of cases, the duration of the disease exceeded one day (724 patients). The typical clinical picture, manifested by cramping abdominal pain, nausea and vomiting, stool and gas retention, and abdominal distension, was observed in the majority of patients (89.1%). Traditional methods of instrumental diagnosis for intestinal obstruction included plain and contrast radiography and ultrasound of the abdominal organs; in some cases, MRI was additionally performed.

Having experience in the surgical treatment of patients with various forms of AIO and working on this problem for over 25 years with specialized in-depth research, we also distinguish III stages in the course of AIO (enteral hypertension, enteral failure, multiple organ failure and peritonitis). We believe that distinguishing these stages is quite sufficient, both from the standpoint of pathogenesis and for the practical surgeon, since each stage determines not only the extent of surgical intervention but also the intensity of postoperative intensive care. In accordance with this classification, at the time of hospitalization, the stage of enteral hypertension was diagnosed in 539 patients (42.1% of cases), the stage of enteral failure was identified in 619 patients (48.4%), and the stage of multiple organ failure and peritonitis was determined in 121 patients (9.5%). Patient distribution by disease stage was based on a comprehensive assessment of clinical, laboratory, instrumental, and intraoperative data. Multiple organ disorders in AIO were diagnosed in the presence of functional insufficiency of two or more organs or systems.

From a pathogenetic point of view, the stage of enteral hypertension is characterized by an acute disturbance of intestinal passage and an increase in intra-intestinal pressure to a level at which hemocirculation in the intestinal wall is still present and its morphological structure is preserved. In this stage, pain syndrome is pronounced, and peristalsis is usually increased. Clinical signs of impaired passage of intestinal contents are not pronounced. Laboratory parameters are within normal fluctuations. During surgical intervention, the afferent loop is slightly altered, the intestinal diameter does not exceed 3–4 cm, its lumen contains a small amount (up to 500 ml) of fluid and a small amount of gas, the wall is not edematous, and peristalsis is normal or increased.

A considerable number of studies have been devoted to water-electrolyte balance disorders in AIO [2, 23]. Certain interest, apparently, may be represented by disturbances of the latter depending on the stage of the disease. Our own specialized studies showed that in stage I of AIO, water-electrolyte balance disorders are absent (Table 1). Apparently, the main mechanism of water-electrolyte balance disorders is impaired absorption due to progressively increasing intra-intestinal pressure. This is observed in stage II of enteral failure. This period, in our opinion, is primarily associated with the appearance of disorders in water-electrolyte balance and, consequently, the appearance and development of acute intestinal failure syndrome (AIFS). The tactics and actions of the clinician during this period should be aimed not only at eliminating the mechanical obstruction but also at combating AIFS in the first place.

In this stage, there are clear clinical, radiological, and surgical signs of developing AIFS. The incipient extracellular dehydration primarily reduces the circulating blood volume (CBV), which, according to our data, decreases by up to 20%. Due to the loss of the liquid part of the blood, hemoconcentration occurs, the number of erythrocytes (4.4±0.04 ×1012/L), hemoglobin (155.1±2.4 g/L), hematocrit (46.7±0.6%) increases, blood rheology changes with an increase in its viscosity, which contributes to microcirculation disorders. The shock index (0.89±0.18) indicates a moderate degree of dehydration. Daily diuresis indicates initial manifestations of oliguria (830.0±16.8 mL/day).

Table 1. Indicators of water-electrolyte balance disorders in acute intestinal obstruction

Laboratory indicatorsStage of obstructionStage of obstructionStage of obstruction    IIIIII    nValuenValuenValueErythrocyte count (1012/L)273.9±0.1334.4±0.04*124.7±0.1*Hb (g/L)27138.4±2.733155.1±2.4*12159.2±7.0Ht (%)1239.9±0.62046.7±0.6*953.1±1.0*Mean erythrocyte volume (fL)1299.6±1.720107.03±1.3*9111.7±1.7*Potassium (mmol/L)214.8±0.1173.5±0.1*113.2±0.1Sodium (mmol/L)21140.1±1.117134.7±1.2*10130.4±1.7Shock index1090.65±0.15960.89±0.18*231.17±0.06*% CBV reduction based on shock index109up to 596up to 2023more than 30Fluid volume in abdominal cavity (mL)100-91500.5±115.519403.6±118.9*Fluid volume in intestine during decompression (mL)100352.5±115.5911900.5±395.5191703.6±318.9Daily diuresis (mL)261400.8±48.838830.3±16.6*14464.3±34.1*Note: * sign indicates statistically significant changes (p <0.05) in relation to the previous stage.

During surgical intervention in this stage, an accumulation of serous-hemorrhagic effusion in the abdominal cavity is observed, averaging about 500.5±115.5 mL. The afferent loop is dilated up to 6–8 cm, containing a large amount of fluid (1900.5±395.5 mL) and gas. Thus, early changes in water-electrolyte balance in stage II of AIO are associated with the appearance of isotonic dehydration.

During surgical intervention, a distended afferent loop is found; its wall is edematous along its entire length from the point of obstruction to the duodenojejunal junction; edema extends to the mesentery; dark spots and streaks are visible under the serosa - traces of hemorrhages due to rupture of intramural intestinal vessels. The intestinal diameter reaches 6–8 cm, peristalsis in the afferent loop is often absent. From 1 to 3 liters of fluid are sequestered into the intestinal lumen; the intestine contains a significant amount of gas. In the abdominal cavity, there is 300 to 800 mL of serous, serous-hemorrhagic, or dark hemorrhagic exudate.

Stage III - the stage of peritonitis. The clinical picture of the disease during this period is characterized by a subsidence of pain against a background of progressively increasing peritoneal symptoms. During laparotomy, a turbid effusion is present in the abdominal cavity; the small intestine is dilated with pronounced marbling of its serosa; peristalsis is absent; tissues are edematous. Careless actions by the surgeon can lead to damage to the serosa, the intestinal mesentery, and undesirable bleeding. During this period, intoxication progresses. The accumulation of toxins in the blood is primarily due to their resorption from the intestinal lumen and the abdominal cavity, as well as disruption of biological oxidation processes and bacterial pathogenicity.

Multiple organ dysfunction of varying severity develops. At this stage of AIO development, peritonitis apparently already acquires the features of an independent disease. Therefore, further assessment of the severity of AIO is, first and foremost, an assessment of the severity of peritonitis, which is well known. With the progression of AIO (stage III), more profound disturbances of water-electrolyte balance, and along with it acid-base balance, occur. Due to the increasing fluid deficit, CBV decreases, which, according to our data, falls by more than 30%. Progressive decrease of the latter can lead to hypovolemic shock. At the same time, the concentration of diethylamine in blood plasma increases 4.6 times, acetaldehyde - 5.2 times, acetone - 4.9 times, isovaleric aldehyde - 3700 times, butyraldehyde - 200 times (chromato-mass spectrometry method) (Table 2). It should be noted that with the progression of the disease, the severity of endogenous intoxication increases. We used the obtained data when prescribing detoxification methods for patients with acute intestinal obstruction.

All patients underwent conservative preoperative preparation, including infusion therapy, the use of antispasmodics and prokinetics, and decompression of the upper and lower gastrointestinal tract. The duration of preoperative preparation in the hospital, in the absence of signs of peritonitis or data suggesting strangulation in patients, ranged from 6 to 11 hours. As a result, in 463 out of 681 patients with abdominal adhesive disease (68.0% of cases), acute adhesive intestinal obstruction was resolved conservatively, accounting for 36.2% of the total number of patients.

Table 2. Structure of endogenous intoxication with intermediate metabolic products in patients with acute intestinal obstruction

Indicators (mass % per 10)Control (n=10)Stage of ileusStage of ileusStage of ileus  I (n=11)II (n=10)III (n=8)Diethylamine0.3±0.021.4±0.1***1.7±0.1***1.2±0.1***Acetaldehyde2.9±0.087±0.3***9.3±0.3***12.2±0.1***Acetone6.5±0.329.6±2.0***28.7±2.7***31.5±2.4***Isovaleric aldehyde0.001±0.00041.8±0.2***2.2±0.1***3.7±0.3***Isopropanol2.2±0.20.5±0.1***0.8±0.1***0.6±0.1***Methyl isocyanide0.12±0.050.5±0.03***0.4±0.020.2±0.04Butyraldehyde0.01±0.0021.4±0.1***1.9±0.1***3.7±0.1***Note: * sign indicates reliability (p <0.05) relative to control.

All other patients were operated on. The main goal of the surgical intervention was to eliminate the intestinal obstruction by removing its cause. If indicated (non-viable intestine, resectable tumor), the operation was supplemented by intestinal resection and completed with one of the options for internal or external drainage of the gastrointestinal tract (intestinal intubation, anastomosis creation, stoma formation). In cases where simultaneous radical elimination of the obstruction cause was impossible (unresectable tumor, widespread peritonitis), drainage operations were performed as the first stage of surgical treatment or as a palliative final intervention.

In total, 816 surgical interventions of varying extent were performed on an emergency and urgent basis, accounting for 63.8% of the total number of patients hospitalized with AIO. The most common methods for eliminating the cause of non-tumor intestinal obstruction were adhesiolysis, performed in 218 patients (26.7%); herniotomy with strangulation relief - in 138 patients (16.9%); intestinal detorsion - in 31 patients (3.8%); gallstone removal - in 13 cases (1.6%); disinvagination - in 4 patients (0.5%). In 164 patients with various, including tumor-related, causes of obstruction, intestinal resection was performed as indicated (20.1% of cases). In 246 (30.2%) of the operated patients (depending on the specific situation), the operation was completed by creating a restorative or bypass anastomosis; in 232 patients (28.4%) - by forming a colostomy; in 71 patients, the operation was completed by forming an enterostomy (8.7% of cases).

Analysis of treatment outcomes revealed a dependence of mortality rate on age, duration of the disease, etiology of obstruction, and extent of surgical intervention. Considering that there were no deaths among patients with conservatively resolved intestinal obstruction, the average overall and postoperative mortality rates were 8.7% and 13.6%, respectively (111 patients). Examining the dependence of the indicator on age revealed the highest number of unfavorable outcomes in the older age groups. In the patient group under 60 years, deaths were observed in 5.9% of cases; in the overall group over 60 years, the rate was 9.8%; and in those over 75 years - 22.3%, which is largely associated with the severity of concomitant general somatic pathology.

For disease duration up to 12 hours, the mortality rate was unexpectedly highest, amounting to 27.8% of cases, whereas among patients hospitalized at a later stage, unfavorable outcomes were observed 4.4 times less frequently. Their frequency in this group was 6.3%. This is probably associated with earlier medical consultation by patients with predominantly strangulation-type obstruction, accompanied by rapid development of intestinal necrosis and a higher frequency of forced intestinal resections.

The mortality rate also varied significantly depending on the etiology of acute intestinal obstruction. In the group of patients with intestinal tumors complicated by obstruction, the rate was 17.9%. In non-tumor ileus, the average mortality rate was 3.8 times lower, at 4.7%, but it depended significantly on the cause of the obstruction. For example, there were no unfavorable outcomes in gallstone intestinal obstruction. Among patients with adhesive obstruction, postoperative mortality was 5.0%, with an overall rate of 1.6% in this group. Elimination of obstruction in strangulated hernia was accompanied by an unfavorable outcome in 12.3% of patients. A significantly higher mortality rate was found in other groups of patients with intestinal obstruction of non-tumor genesis. For instance, in intestinal volvulus it was 18.4%, and in knotting and intussusception - 42.9% and 40%, respectively, which may be associated with a high frequency of extensive intestinal resections and a small number of observations in these groups.

Analysis of mortality depending on the extent of surgical intervention showed the greatest dependence of the indicator on the need to perform intestinal resection during the elimination of intestinal obstruction. Thus, in the group of patients operated on without intestinal resection, the mortality rate ranged from 0% in biliary ileus to 5% in adhesiolysis and 7% in the creation of a decompressive enterostomy. It was higher in the creation of a bypass anastomosis (8.5%), performance of intestinal detorsion (9.6%), and colostomy formation (14.2%). In the overall group of patients undergoing intestinal resection, regardless of the etiology of obstruction and the type of surgical completion, the mortality rate was significantly higher, amounting to 23.2%.

Conclusions

Conservative therapy showed the greatest effectiveness in abdominal adhesive disease. In 68% of cases, the episode of adhesive intestinal obstruction was resolved conservatively (without surgery). In 20.1% of cases, surgical intervention for acute intestinal obstruction required intestinal resection. The mortality rate in tumor-related obstruction was 3.8 times higher than that in non-tumor obstruction. The mortality rate in the overall group of patients, without considering the etiology of intestinal obstruction, depended on patient age and the extent of the operation. Age over 75 years and the need for intestinal resection, regardless of the timing of hospitalization, were prognostic risk factors for an unfavorable outcome. With increasing severity of AIO, mortality progressively increased. In stage III obstruction, compared to stage I, mortality increased more than 10-fold.