Effect of Surgical Technique on the Microstructure and Microcirculation of the Small Intestine Stump during Delayed Anastomosis: Multimodal OCT Data.

The aim of the study was to use multimodal optical coherence tomography (MM OCT) to evaluate microstructure and microcirculation in the proximal and distal sections of the intestine relative to the resected area in acute mesenteric ischemia. MATERIALS AND METHODS: The study was carried out using three groups of male Wistar rats weighing 270-435 g (n=18). Acute occlusive arterial ischemia of the small intestine was initiated in all animals. After 80-90 min, the ischemic non-viable part of the intestine was resected, and the operation was completed by stoma exteriorization (group 1, n=6), by applying purse-string sutures (group 2, obstructive resection, n=6), or by internal drainage of the proximal and distal ends of the small intestine (group 3, bypass, n=6). Relaparotomy and anastomosis formation were performed 2 days later.With the help of MM OCT at each stage of the surgical intervention, images were obtained from the serous membrane side: the intestinal wall microstructure (layers) was viewed using cross-polarization OCT (CP OCT) and the intramural circulation - using optical coherent angiography (OCA). The MM OCT images obtained from the terminal intestine sections immediately after resection and 2 days later (before the anastomosis formation) were compared between the experimental groups, as well as with the pre-ischemic data (norm). All resected sections of the intestine were then histologically examined. The MM OCT data were compared with the histological and intravital macroscopy data. RESULTS: As a result of studying the intestinal wall microstructure by in vivo CP OCT, it was found that during ostomy (group 1) and obstructive resection (group 2), the images showed signs of tissue edema and destructive changes in the mucous membrane that were confirmed histologically, while with bypass surgery (group 3), there were minimal changes as compared with the norm.According to the OCA data, on day 2 of ostomy in the proximal and distal segments of the intestine, there was a noticeable disappearance of small and medium blood vessels; mainly large arteries and veins could be visualized. Following obstructive resection (purse-string suturing) or bypass surgery, the most noticeable changes (a decrease in the number of visualized blood vessels) were observed in the distal part of the intestine. The L index calculated from OCA images and characterizing the total length of the intramural perfused vasculature, showed a statistically significant decrease during ostomy: 12.18 [10.40; 14.20] µm - in the proximal and 10.67 [7.98; 13.05] µm - in the distal section; for comparison, the L index before ischemia was 18.90 [17.98; 19.73] µm and 18.74 [17.46; 19.90] µm, respectively (p=0.0001). In obstructive resection (group 2), statistically significant differences in the L parameter were found only for the distal bowel section: 16.39 [12.37; 18.10] µm compared with 18.74 [17.46; 19.90] µm before ischemia (p=0.041). After bypass surgery (group 3), there were no significant deviations in the L index. CONCLUSION: By using MM OCT, we found that in treating the remaining sections of the intestine after its emergency resection for acute mesenteric ischemia, the type of surgical technique determines the tissue structure in the period before the delayed anastomosis is applied.The least pronounced and most balanced changes occur in the proximal and distal segments of the intestine when operated using the bypass technique. However, to recommend this type of surgery, the development of reliable, safe, and effective bypass instruments is needed.

Viability of Bacteriophages in the Complex Hydrogel Wound Dressings in vitro.

Using bacteriophages to overcome the increasing resistance of microorganisms to antibiotics is a novel research venue of clinical importance. Among other challenges, this technique is expected to create and maintain an adequate local concentration of bacteriophages at the site of application. In addition, the possibility of combining the phage preparation with antioxidants and anesthetics may provide new options for stimulating the reparative process. The aim of the study was to assess the viability and lytic activity of bacteriophages incorporated into a hydrogel-based wound dressing that contains polyvinyl alcohol, phosphate buffer, with optional additions of succinic acid and lidocaine. Materials and Methods: A technique for incorporating bacteriophages into the complex hydrogel wound dressing ex tempore has been proposed. The bacteriolytic activity of phages inside the hydrogel was determined using standard microbiological techniques. Specifically, we used nutrient media with lawn cultures of Staphylococcus aureus added with the following antibacterial combinations: bacteriophages + succinic acid, bacteriophages + lidocaine, and bacteriophages + succinic acid + lidocaine. The lytic activity of bacteriophages was assessed within 1 to 7 days after the formation of the hydrogel. Results: In all samples containing bacteriophages, the presence of viable and lytically active phages was noted within 1 to 7 days, as evidenced by the "negative colonies" on the culture lawns. On days 1 to 3, no secondary growth was recorded in the phage-containing samples. In hydrogel samples containing phages, succinic acid, and lidocaine, secondary bacterial colonies were detected starting from day 4 indicating some reduction in the lytic activity. Conclusion: The results suggest that bacteriophages immobilized in the hydrogel maintain their viability and lytic activity, and this activity persists when the phages are combined with succinic acid and lidocaine.

Trans-Serosal Multimodal Optical Coherence Tomography for Visualization of Microstructure and Blood Circulation of the Small Intestine Wall.

The aim of the study was to evaluate the performance of trans-serosal multimodal OCT (MM OCT) in in vivo detecting of changes in microstructure and blood circulation of the small intestine wall caused by arteriovenous ischemia resulted from intestine strangulation. MATERIALS AND METHODS: In experiments on Wistar rats (n=22), we examined the small intestine wall in vivo using MM OCT; the access to the intestine was reached through laparotomy. The microvasculature and microstructure of the wall were studied before and after acute arteriovenous ischemia created by ligation of a small bowel segment. The results were then added with data obtained from histological and intravital microscopic examination. RESULTS: Trans-serous MM OCT allowed us to visualize the bowel wall to its entire thickness, distinguish between the serous-muscular and mucous-submucosal layers, and detect the villi and functioning blood vessels. The structures were best seen after a fat emulsion had been administered into the bowel lumen. In OCT images made in the optical coherent angiography (OCA) mode, large paired vessels (arteries and veins) and micro-vessels with a diameter of >15 µm could be seen. Most of the blood vessels were imaged in the depth range of 80-300 µm from the surface. Capillaries with a diameter of 7-10 µm were not seen, but they produced an overall bright background. In the OCA images reconstructed from a volume of 2.4×2.4×1.8 mm, the total length of the vascular bed before ischemia was 18.3 [16.6; 19.8] mm.Strangulation of the intestinal loop was associated with changes in the CP OCT picture: the villi-associated vertical pattern and shadows of blood vessels disappeared and the depth of tissue visualization in the cross-channel decreased. The optical equivalents of the serous-muscular layer were preserved; after 180±12 min of ischemia, their proportion in the intestinal wall thickness increased from 25 [18; 32] to 42 [31; 55]% (p=0.031). At that time-point, OCA images of the strangulated bowel loop looked all similar: a uniform dark background with isolated fragmentary large vessels and no signs of blood flow in the microvascular network. CONCLUSION: Trans-serous MM OCT provides for in vivo visualization of microstructures critical for surgical gastroenterology: the intestinal wall layers including villi and blood vessels of each layer, as confirmed by histological analysis. Destructive processes in the intestinal wall resulting from bowel ligation bring about optical changes, which can be detected using real-time MM OCT.

[Comparative diagnostic value of various methods of intracavitary pressure measurement in abdominal compartment syndrome]. / Sravnitel'naia diagnosticheskaia tsennost' metodov opredeleniia vnutripolostnogo davleniia pri abdominal'nom kompartment-sindrome.

AIM: To investigate diagnostic value of various methods of biophysical somatic parameters (BSP) monitoring in peritonitis complicated by abdominal compartment syndrome. MATERIAL AND METHODS: 220 patients with advanced peritonitis complicated by compartment syndrome were enrolled. Sensitivity, specificity, diagnostic value of the measurement of intraabdominal, intraintestinal, intrathoracic pressure, paravulnar tissues tension depending on abdominal hypertension severity were determined. RESULTS: BSP control including intraabdominal, intraintestinal, intrathoracic pressure and paravulnar tissues tension is effective for BPS disturbances diagnosis and abele to detect them significantly more often (p=0.037) compared with M. Cheatham's method alone.

[The value of optical coherence tomography and morphometry in evaluating the peripancreatic adipose tissue in infected pancreatic necrosis]. / Znachenie opticheskoi kogerentnoi tomografii i morfometrii dlia otsenki sostoianiia parapankreaticheskoi zhirovoi kletchatki pri infitsirovannom pankreonekroze.

OBJECTIVE: To investigate the morphometric and optical coherence tomography (OCT) characteristics of the microstructure of retroperitoneal peripancreatic adipose tissue during passive drainage and active perfusion-aspiration drainage for infected pancreatic necrosis. MATERIAL AND METHODS: The authors analyzed 74 samples of peripancreatic adipose tissue obtained from 37 patients with passive (Group 1) and active perfusion-aspiration drainage (Group 2) of a focus of peripancreatitis. The tissues were examined with OCT, then fixed in a formalin solution and underwent histological examination, including morphometric one. RESULTS: The examined groups showed qualitative and quantitative differences in the tissue microstructure. In Group 1 samples, the proportion (median (upper quartile; lower quartile)) of interlobular connective tissue was 5.6 (3.9; 6.1)%; and that of adipocytes was 44.6 (41.2; 51.6)%. Necrotic tissue occupied 46.2 (35.6; 56.1)% of the area of specimens. The OCT images of necrotic tissue displayed a preponderance of unstructured regions with a high signal level while the parenchymal areas showed a cellular structured pattern. In Group 2 samples, the proportion of interlobular connective tissue was 16.2 (11.4; 19.7)%, and that of adipocytes was 68.5 (59.7; 71.2)%. At the same time, Group 2 exhibited necrosis - 14.4 (11.5; 19.2%) that was 3.2 times less than in Group 1. The OCT images of Group 2 samples showed a preponderance of cellular structured regions characteristic of the parenchyma, with pronounced stromal elements, which corresponded to the histological pattern. CONCLUSION: Active perfusion-aspiration drainage of peripancreatic adipose tissue versus passive drainage is associated with a smaller proportion of necrotic tissue (14.4% versus 46.2%; p≤0.05) and a larger proportion of a stromal vascular component (16.2% vs. 5.6%; p≤0.05). OCT could qualitatively distinguish viable fat tissue parenchyma from necrotic areas, without specially preparing the samples, which was confirmed by histomorphometric results.