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The influence of hypervolemia and intraoperative administration of nitroglycerine on gastric tube microperfusion remains unclear The present study aimed to investigate the impact of different hemodynamic settings on gastric tube microperfusion quantified by fluorescence imaging with Indocyanine green (ICG-FI) as a promising tool for perfusion evaluation. Three groups with seven pigs each were formed using noradrenaline, nitroglycerin, and hypervolemia for hemodynamic management, respectively. ICG-FI, hemodynamic parameters, and transit-time flow measurement (TTFM) in the right gastroepiploic artery were continuously assessed. Fluorescent microspheres (FM) were administered, and the partial pressure of tissue oxygen was quantified. The administration of nitroglycerine and hypervolemia were both associated with significantly impaired microperfusion compared to the noradrenaline group quantified by ICG-FI. Even the most minor differences in microperfusion could be sufficiently predicted which, however, could not be represented by the mean arterial pressure measurement. Histopathological findings supported these results with a higher degree of epithelial damage in areas with impaired perfusion. The values measured by ICG-FI significantly correlated with the FM measurement. Using tissue oxygenation and TTFM for perfusion measurement, changes in microperfusion could not be comprehended. Our results support current clinical practice with restrictive volume and catecholamine administration in major surgery. Hypervolemia and continuous administration of nitroglycerine should be avoided. [ABSTRACT FROM AUTHOR]

Objectives: Evaluation of intestinal perfusion remains subjective and depends on the surgeon´s individual experience. Intraoperative quality assessment of tissue perfusion with indocyanine green (ICG) fluorescence using a near-infrared camera system has been described in different ways and for different indications. The aim of the present study was to evaluate fluorescent imaging (FI) in the quantitative assessment of intestinal perfusion in a gastric tube model in pigs and to compare the results to results obtained with florescent microspheres (FM), the gold standard for tissue perfusion. Methods: Seven pigs (56.0±3.0 kg), both males and females, underwent gastric tube formation after transection and ligation of the gastric arteries, except the right gastroepiploic artery, to avoid collateral blood flow. After baseline assessment (T0), hypotension (T1) was induced by propofol (Karampinis et al 2017) (< 60 mmHg). Then, propofol was paused to obtain normotension (T2, Mean arterial pressure (MAP) 60–90 mmHg). Finally, hypertension (T3, MAP>90 mmHg) was induced by norepinephrine. Measurements were performed in three regions of interest (ROIs) under standardized conditions: the fundus (D1), corpus (D2), and prepyloric area (D3). Hemodynamic parameters and transit-time flow measurement (TTFM) in the right gastroepiploic artery were continuously assessed. FI, FM and the partial pressure of tissue oxygen (TpO2) were quantified in each ROI. Results: The study protocol could successfully be performed during stable hemodynamics. Flow in the gastroepiploic artery measured by transit time flow measurement (TTFM) was related to hemodynamic changes between the measurements, indicating improved blood flow with increasing MAP. The distal part of the gastric tube (D1) showed significantly (p<0.05) impaired perfusion compared to the proximal parts D3 and D2 using FM. ICG-FI also showed the highest values in D3 and the lowest values in D1 at all hemodynamic levels (T1-T3; p<0,05). Conclusion: Visual and quantitative assessment of gastric tube perfusion is feasible in an experimental setting using ICG-FI. This might be a promising tool for intraoperative assessment during visceral surgery in the future. [ABSTRACT FROM AUTHOR]