Alterations in intestinal serosal microcirculation precipitated by the Pringle manoeuvre

The Use of Newly Synthesized Composite Scaffolds for Bone Regeneration - A Review of Literature

At present, clamping of the portal triad is a widespread surgical procedure in hospitals. Such an operation can prevent pathological changes in the organs. However, the optimal time for clamping remains unclear. To determine the starting time of irreversible morphological changes in the small intestine due to the clamping of the portal triad. The study was carried out on rats (n=94). Animals were randomly subdivided into 4 groups based on the duration of clamping of the portal triad (PT): I control group (CG; without clamping the PT; n=10); II intervention group (6-IG; clamping PT for 6 min; n=28); III intervention group (12-IG; clamping time of the PT for 12 min; n=28); IV intervention group (24-IG; clamping time of the PT for 24 min; n=28). In groups 6- IG, 12-IG, 24-IG, after clamping the portal triad, animals were withdrawn from the experiment after 3 hours, 6 hours, 12 hours, 1 day, 3 days and 7 days. Morphological changes in the small intestine were assessed by measuring the diameter of the lumen of micro-vessels. In addition, the mortality in the groups was analysed as well. In the CG group, the diameter of the arterioles of the small intestine was 34±4 μm, the diameters of pre-capillaries were 15±2μm, the capillaries were 5.4±1 μm, the post-capillaries were 18±2 μm, and the diameter of the lumen of the venues was 40±3 μm. In the 6-IG group (on the 3rd day), the structure of the small intestine showed the recovery signs. By the 7th day, the indicators returned to their original values. In the 12-IG group, the parameters of the small intestine were restored on the seventh day that corresponds to the usual course of the disease. However, in the 24-IG group, changes in these organs persisted until the end of the study. No deaths were reported in the CG and 6-IG animal groups. Mortality among rats of the 12-IG group was 14.3%, while in the 24-IG group with PT clamping for 24 minutes it was 42.8%, respectively. The morphological changes in the microvasculature of the small intestine after 6-minute PT clamping showed a tendency to recover (back to the control parameters). Nevertheless, after 24 minutes of clamping, the changes in the intestinal tissue were irreversible.

A Toolbox to Investigate the Impact of Impaired Oxygen Delivery in Experimental Disease Models

Impaired oxygen utilization is the underlying pathophysiological process in different shock states. Clinically most important are septic and hemorrhagic shock, which comprise more than 75% of all clinical cases of shock. Both forms lead to severe dysfunction of the microcirculation and the mitochondria that can cause or further aggravate tissue damage and inflammation. However, the detailed mechanisms of acute and long-term effects of impaired oxygen utilization are still elusive. Importantly, a defective oxygen exploitation can impact multiple organs simultaneously and organ damage can be aggravated due to intense organ cross-talk or the presence of a systemic inflammatory response. Complexity is further increased through a large heterogeneity in the human population, differences in genetics, age and gender, comorbidities or disease history. To gain a deeper understanding of the principles, mechanisms, interconnections and consequences of impaired oxygen delivery and utilization, interdisciplinary preclinical as well as clinical research is required. In this review, we provide a "tool-box" that covers widely used animal disease models for septic and hemorrhagic shock and methods to determine the structure and function of the microcirculation as well as mitochondrial function. Furthermore, we suggest magnetic resonance imaging as a multimodal imaging platform to noninvasively assess the consequences of impaired oxygen delivery on organ function, cell metabolism, alterations in tissue textures or inflammation. Combining structural and functional analyses of oxygen delivery and utilization in animal models with additional data obtained by multiparametric MRI-based techniques can help to unravel mechanisms underlying immediate effects as well as long-term consequences of impaired oxygen delivery on multiple organs and may narrow the gap between experimental preclinical research and the human patient.

Automatic Liver Viability Scoring with Deep Learning and Hyperspectral Imaging

Hyperspectral imaging (HSI) is a non-invasive imaging modality already applied to evaluate hepatic oxygenation and to discriminate different models of hepatic ischemia. Nevertheless, the ability of HSI to detect and predict the reperfusion damage intraoperatively was not yet assessed. Hypoxia caused by hepatic artery occlusion (HAO) in the liver brings about dreadful vascular complications known as ischemia-reperfusion injury (IRI). Here, we show the evaluation of liver viability in an HAO model with an artificial intelligence-based analysis of HSI. We have combined the potential of HSI to extract quantitative optical tissue properties with a deep learning-based model using convolutional neural networks. The artificial intelligence (AI) score of liver viability showed a significant correlation with capillary lactate from the liver surface (r = −0.78, p = 0.0320) and Suzuki’s score (r = −0.96, p = 0.0012). CD31 immunostaining confirmed the microvascular damage accordingly with the AI score. Our results ultimately show the potential of an HSI-AI-based analysis to predict liver viability, thereby prompting for intraoperative tool development to explore its application in a clinical setting.

Real-time observation of microcirculatory leukocytes in patients undergoing major liver resection

Ischemia/reperfusion injury and inflammation are associated with microcirculatory dysfunction, endothelial injury and glycocalyx degradation. This study aimed to assess microcirculation in the sublingual, intestinal and the (remnant) liver in patients undergoing major liver resection, to define microcirculatory leukocyte activation and its association with glycocalyx degradation. In this prospective observational study, the microcirculation was assessed at the beginning of surgery (T0), end of surgery (T1) and 24 h after surgery (T2) using Incident Dark Field imaging. Changes in vessel density, blood flow and leukocyte behaviour were monitored, as well as clinical parameters. Syndecan-1 levels as a parameter of glycocalyx degradation were analysed. 19 patients were included. Sublingual microcirculation showed a significant increase in the number of rolling leukocytes between T0 and T1 (1.5 [0.7-1.8] vs. 3.7 [1.7-5.4] Ls/C-PCV/4 s respectively, p = 0.001), and remained high at T2 when compared to T0 (3.8 [3-8.5] Ls/C-PCV/4 s, p = 0.006). The microvascular flow decreased at T2 (2.4 ± 0.3 vs. baseline 2.8 ± 0.2, respectively, p < 0.01). Duration of vascular inflow occlusion was associated with significantly higher numbers of sublingual microcirculatory rolling leukocytes. Syndecan-1 increased from T0 to T1 (42 [25-56] vs. 107 [86-164] ng/mL, p < 0.001). The microcirculatory perfusion was characterized by low convection capacity and high number of rolling leukocytes. The ability to sublingually monitor the rolling behaviour of the microcirculatory leukocytes allows for early identification of patients at risk of increased inflammatory response following major liver resection.