Gastric Tissue Damage Analysis Generated by Ischemia: Bioimpedance, Confocal Endomicroscopy, and Light Microscopy

Abstract

The gastric mucosa ischemic tissular damage plays an important role in critical care patients' outcome, because it is the first damaged tissue by compensatory mechanism during shock. The aim of the study is to relate bioimpedance changes with tissular damage level generated by ischemia by means of confocal endomicroscopy and light microscopy. Bioimpedance of the gastric mucosa and confocal images were obtained from Wistar male rats during basal and ischemia conditions. They were anesthetized, and stain was applied (fluorescein and/or acriflavine). The impedance spectroscopy catheter was inserted and then confocal endomicroscopy probe. After basal measurements and biopsy, hepatic and gastric arteries clamping induced ischemia. Finally, pyloric antrum tissue was preserved in buffered formaldehyde (10%) for histology processing using light microscopy. Confocal images were equalized, binarized, and boundary defined, and infiltrations were quantified. Impedance and infiltrations increased with ischemia showing significant changes between basal and ischemia conditions (P < 0.01). Light microscopy analysis allows detection of general alterations in cellular and tissular integrity, confirming gastric reactance and confocal images quantification increments obtained during ischemia.

In vivocharacterization of ischemic small intestine using bioimpedance measurements

“…Radhakrishnan et al measured in-vivo with two small wire electrodes on the surface of rat intestine and found that intestinal edema led to decreasing impedance (Radhakrishnan et al, 2007). Beltran et al have done a lot of work related to experiments and instrumentation using a four-electrode probe inside the intestinal lumen and have reported the ability to detect mucosal injury (Beltran et al, 2007, Beltran et al, 2013b, Beltran and Sacristan, 2015.…”

“…The most commonly used electrode setup to measure the electrical properties of the small intestine has been to use an intraluminal 4-electrode ring setup (Bloch et al, 2017, Beltran et al, 2005, Beltran et al, 2013a, Beltran et al, 2007, Beltran et al, 2013b, Beltran and Sacristan, 2015, Gonzalez et al, 2007, Gonzalez et al, 2003, sending a current between the outer electrode rings, while measuring the voltage across the inner electrode rings, with the assumption that some of the current passes through the mucosal layer affecting the measured complex impedance ( Figure 9). As the current with the intraluminal 4-ring electrode setup will only pass through a small part of the mucosa, we estimate that this method is not usable with respect to assessment of intestinal viability.…”

“…To the best of our knowledge, the present work is the first to use trans-intestinal measurements to assess intestinal viability. Recent studies related to bioimpedance and the small intestine have mainly been focused on intraluminal catheters for assessment of changes in the electrical properties of the mucosa, to detect the presence of ischemia (Gonzalez et al, 2007, Gonzalez et al, 2003, Beltran et al, 2005, Beltran et al, 2013a, Beltran et al, 2007, Beltran et al, 2013b, Beltran and Sacristan, 2015. The 4-electrode ring catheter method has been shown to be unreliable (Bloch et al, 2017).…”

Feasibility of Bioelectrical Impedance Spectroscopy Measurement before and after Thoracentesis

“…An increase in the amount of fluid in the measured compartments decreases the bioelectrical impedance. BIS measurements have been used for monitoring hemodialysis [ 8 ], body fat analysis [ 9 ], or characterizing tissue properties [ 10 , 11 ]. Although the use of bioelectrical impedance might point out the underlying disease, for instance cardiac or noncardiac cause of dyspnea, strong data supporting this hypothesis are still lacking [ 12 ].…”

Gastrointestinal ischemia monitoring through impedance spectroscopy as a tool for the management of the critically ill

“…We used that parameter to classify injured mucosa (patients in red in Figure 9) in human gastric tissue with the proposed thresholds, showing a very high incidence of gastric ischemia in the critically ill. 28 We also observed alterations in cellular and tissular integrity by light microscopy analysis that confirmed gastric reactance increments obtained during ischemia in a rat model. 21 Gastric ischemia results from diffuse or localized vascular insufficiency due to etiologies such as systemic hypotension, vasculitis, or disseminated thromboembolism. 35 Recently it has been reported that gastrointestinal dysfunction is common in critically ill patients, and may have bad prognosis, 1,36 so improving diagnosis techniques in critically ill patients help the generation of guided therapies in a faster and more efficient way, preventing Multiple Organ Dysfunction Syndrome (MODS) and death.…”