Radiological Diagnosis of Thrombotic Complications in Patients with Surgical Diseases

The research is dedicated to the problem of radiological diagnosis of thrombotic complications, such as pulmonary artery embolism and deep vein thrombosis, in patients who have undergone surgical interventions. The work analyzes the effectiveness of modern radiological methods, including spiral computed tomography and magnetic resonance angiography, for detecting these pathologies. Special attention is paid to the development of optimal diagnostic and preventive algorithms for thrombotic complications in the perioperative period, aimed at increasing the accuracy of disease detection and reducing mortality among surgical patients.

Relevance of the Research

Pulmonary artery embolism (PAE) is one of the most common and dangerous complications of many diseases, the postoperative and postpartum periods, adversely affecting their course and outcome.

PAE, in a special report by the World Health Organization (WHO), is recognized as one of the most common cardio-pulmonary diseases in America and Europe [132]. In the structure of mortality from cardiovascular diseases, it occupies the third place after myocardial infarction and stroke [20,22,28,49,60,85,198].

PAE is directly related to the development of deep vein thrombosis (DVT) of the lower extremities and pelvis, therefore, at present, these two diseases are generally combined under one name - venous thromboembolism (VTE) [74].

In the majority of cases (up to 80%), venous DVT in the postoperative period proceeds without any symptoms and becomes 'apparent' only upon the development of PAE or the appearance of signs of venous insufficiency [41].

According to global statistics, DVT, detected using the fibrinogen accumulation test I or phlebography, is registered in 5–77% of patients operated on at the age of 40 and older, provided that the duration of the surgical intervention exceeds 1 hour [2].

In recent years, as many authors note, the frequency of PAE has increased by 2.5 times worldwide [22,34,56,68,170,204]. More than 25% of all cases of PAE are associated with various surgical interventions [40].

Mortality among patients without pathogenetic therapy, according to various authors, is 40–70%, while with timely started therapy it ranges from 2 to 8% [22,47,51,69,179].

Mortality from massive PAE is highest after orthopedic interventions – 24%, for lung operations it is 17.9%, and for abdominal operations – 11.5% [35].

In our country, PAE complicates 0.1–0.3% of all surgical operations. It is assumed that for every 5 million operations, PAE occurs in 150 thousand patients, with a fatal outcome in 8 thousand patients [22].

Despite the development of modern diagnostic methods, PAE is not diagnosed in 30–70% of patients during life, or it proceeds under the guise of another disease. Although the source of 65 to 90% of emboli is the veins of the lower extremities, and there are reports that about 50% of patients with DVT of the calf and thigh suffer from PAE in an asymptomatic form, less than 30% of patients with an established diagnosis of thromboembolism have signs and symptoms caused by venous thrombosis [203].

This necessitates timely diagnosis of the disease. Diagnosis of PAE is a difficult task in connection with the fact that the clinical picture is associated with the exacerbation of the underlying disease (ischemic heart disease, chronic heart failure, chronic lung diseases) or is one of the complications of oncological diseases, injuries, extensive surgical interventions.

In the complex of diagnostic methods currently used in the examination of patients with PAE, radiological diagnostic methods have a decisive significance. However, the recognition of PAE, especially of small branches, remains problematic. Diagnostic schemes include different methods that are either sufficiently sensitive but not specific enough (scintigraphy), or invasive and quite expensive (angiopulmonography), or characterized by insufficient sensitivity for detecting clots in the veins of the calf and small pelvis (ultrasonography). Traditional X-ray examination is highly ineffective. Spiral computed tomography angiography (SCTA) of the pulmonary arteries with bolus injection of contrast medium is currently considered sufficiently highly sensitive and specific in the detection of PAE. Magnetic resonance angiography (MRA) is currently an expensive method not available to all medical institutions.

At present, new diagnostic schemes for PAE are used. However, most of them are aimed at detecting already developed PAE. At the same time, diagnostic algorithms aimed at detecting covertly flowing DVT of the lower extremities before planned surgical intervention in patients at high risk of developing venous thromboembolic complications (VTEC) have not been proposed.

All this makes the problem of searching for new algorithms for examination and treatment of patients with thrombotic complications relevant, taking into account the available material and technical equipment of the medical institution; clinical effectiveness and economic feasibility of diagnostic methods.

Goal of the Research

To increase the efficiency of the diagnosis of thrombotic complications in patients with surgical diseases by using a complex of modern radiological research methods.

Tasks of the Research

1. To study the frequency, character, risk factors, and clinical manifestations of thrombotic complications in patients with surgical diseases.

2. To determine the effectiveness of radiological diagnostic methods in the examination of patients with thrombotic complications.

3. To develop an algorithm for the diagnosis of pulmonary artery embolism in surgical patients.

4. To develop an algorithm for the prevention of thrombotic complications in patients with surgical diseases in the perioperative period.

Scientific Novelty

- The frequency, character, risk factors, and clinical manifestations of thrombotic complications in patients with surgical diseases have been studied.

- The effectiveness of radiological diagnostic methods of thrombotic complications has been analyzed and demonstrated.

- An algorithm for the diagnosis of PAE in patients of the surgical profile has been developed.

- An algorithm for the prevention of thrombotic complications in patients with surgical diseases in the perioperative period has been developed.

Practical Significance

- Methodologies of spiral computed tomography and magnetic resonance angiography of the pulmonary arteries have been introduced into clinical practice for the detection of PAE and the assessment of its localization, extent, as well as spiral computed tomography venography for the detection of a possible source of pulmonary embolism.

- An algorithm for the diagnosis of PAE in patients with surgical diseases has been developed.

- An algorithm for the prevention of thrombotic complications in patients in the perioperative period has been developed.

- The complex use of radiological diagnostic methods allows improving the percentage of intraoperative diagnosis of thrombotic complications in patients with surgical diseases, prescribing timely and adequate treatment methods, and reducing the number of fatal PAE cases.

Main Propositions for Defense

1. General clinical methods of examination of patients with suspected development of thrombotic complications (X-ray of chest organs, coagulationogram analysis) have an auxiliary value; negative results of none of them allow reliably excluding PAE. The diagnostic accuracy of PAE according to data of the standard complex of examination is 50%, sensitivity is 25%, specificity is 66.6%.

2. Spiral computed tomography angiography of the pulmonary arteries is the optimal method in the diagnosis of PAE, allowing reliably (accuracy – 90%, sensitivity – 85%, specificity – 100%) to assess the extent, localization of pulmonary vessel damage, detect complications that have arisen, and the possible source.

3. A combination of high-tech radiological diagnostic methods, including X-ray, ultrasonography, spiral computed tomography, allows reliably (accuracy – 94.5%, sensitivity – 92%, specificity – 96.7%) to detect thrombotic complications in surgical patients.

4. The complex use of radiological diagnostic methods allows developing an optimal algorithm for the diagnosis of PAE, an algorithm for the prevention of thrombotic complications in patients with surgical diseases.

Implementation of Research Results into Practice

The results of the research are used in the practical work of surgical and resuscitation departments of the Emergency Medical Aid Hospital of Ufa, in lecture material of the Department of Radiological Diagnosis and Radiation Therapy with a course of IPPO of the Bashkir State Medical University.

Dissertation Defense

The main provisions of the dissertation were reported at: the II Congress of Anesthesiologists and Reanimatologists of the Volga Federal District (Ufa, 2005), the 5th Anniversary Republican Conference of Young Scientists of the Republic of Bashkortostan "Medical Science - 2006" (Ufa, 2006), the Russian scientific conference with international participation "Issues of Morphology" (Ufa, 2006), the 5th Anniversary Conference of Young Scientists of the Republic of Bashkortostan "Scientific Breakthrough - 2006" (Ufa, 2006), the First Scientific and Practical Conference "High-tech Methods of Diagnosis and Treatment in Abdominal Surgery - Problems of Imaging" (Moscow, 2006).

Publications

Based on the materials of the dissertation, 8 works have been published.

Volume and Structure of the Dissertation

The dissertation is presented on 150 pages of typed text, consists of an introduction, a literature review, two chapters of own research, conclusion, conclusions, practical recommendations, and a reference list, and contains 22 tables, 9 figures. The reference list includes 74 domestic and 143 foreign authors.