(1) Introduction: Negative pressure wound therapy (NPWT) is a frequently applied open abdomen (OA) treatment. There are only a few experimental data supporting this method and describing the optimal settings and pressure distribution in the abdominal cavity during this procedure. The aim of our study was to evaluate pressure values at different points in the abdominal cavity during NPWT in experimental abdominal compartment syndrome (ACS) animal model; (2) Methods: In this study (permission Nr. 13/2014/UDCAW), 27 Hungahib pigs (15.4–20.2 kg) were operated on. ACS was generated by implanting a plastic bag in the abdomen through mini-laparotomy and filled with 2100–3300 mL saline solution (37 °C) to an intraabdominal pressure (IAP) of 30 mmHg. After 3 h, NPWT (Vivano Med® Abdominal Kit, Paul Hartmann AG, Germany) or a Bogota bag was applied. The NPWT group was divided into −50, −100 and −150 mmHg suction groups. Pressure distribution to the abdominal cavity was monitored at 6 different points of the abdomen via a multichannel pressure monitoring system; (3) Results: The absolute pressure levels were significantly higher above than below the protective layer. The values of the pressure were similar in the midline and laterally. Amongst the bowels, the pressure values changed periodically between 0 and −12 mmHg which might be caused by peristaltic movements; (4) Conclusions: The porcine model of the present study seems to be well applicable for investigating ACS and NPWT. It was possible to provide valuable information for clinicians. The pressure was well distributed by the protective layer to the lateral parts of the abdomen and this phenomenon did not change considerably during the therapy.
ACS resulted in impairment of macro- and micro-rheological parameters and abdominal organs' microcirculation. All of the used techniques improved the results, however, applying Bogota-bag or -150 mmHg vacuum set showed worse microcirculatory and micro-rheological data than the settings at -100 or -50 mmHg.
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Introduction:The biomechanical properties of small vessels and microvascular anastomoses have not been studied completely yet. However, in case of vascular injury and various microsurgical reconstructive procedures a safe anastomosis is essential. Quick and reliable tests are needed to test various anastomoses in research and in teaching courses as well for quality control and proper feedback. We aimed to compare selected biomechanical properties of the simple interrupted, the continuous suture and the modified Lauritzen's sleeve-technique.Materials and methods: Sixty femoral arteries from chicken thigh biopreparates and 12 abdominal aortas from rats were used in this study. In case of the pressure resistance test the groups were: the simple interrupted, the continuous suture and the modified Lauritzen's sleeve-technique. The tensile-strength, elongation and elasticity measurement groups were the simple interrupted and continuous sutures with 8 and 12 stitches. Furthermore the suture materials in various conditions (simple thread, knotted threads, stitch with intact and damaged threads) were also compared. The tensile-strength and the pressure probe devices were custom made in cooperation with the Faculty of Informatics. Results:The average diameter of the chicken femoral arteries was 3.25 ±0.38 mm. The sleeve-technique showed the biggest pressure drop (56 ±16.41 mmHg), however, it was the fastest method. The tensilestrength of simple interrupted suture was 4.55 ±0.7 Newton (N), being lower than of the intact vessel (6.8 ± 1.4 N). The tensile-strength did not differ significantly between the 12-stitch simple interrupted and continuous sutures, however, the latter was stronger. The anastomoses made on thread model were significantly stronger than the ones on vessels. Conclusion:The main variables were the number of stitches and the strength of the vessel. The pressure drop was not correlated with the stitch number. One incorrect stitch can dramatically increase the leakage. Although the sleeve-technique is quick to be performed, it cannot withstand high pressure. The suture material itself is far stronger then the vessel. The vessel tensile strength was decreased in the anastomoses. For the given vessel diameter more than 8 stitches should be used.
This paper introduces long-term tensile and quasi-relaxation tests of polyvinylchloride (PVC) fibers. During creep, the longitudinal and cross-sectional changes were measured of unaged and aged PVC fibers loaded with the same weight. In the quasi-relaxation section, where deformation was frozen, the stress changes were determined. During the examination of the creep, the Poynting-Thomson model described the phenomenon with sufficient accuracy (min R 2 0.9628) and the calculated parameter values characterized the aging process well. In the relaxed phase, the Poynting-Thomson model was not adequate, and, therefore, the second-order time derivatives were also involved in the applied model. Aging significantly resulted in parameter changes in this section as well.
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