Oxygen levels during negative pressure wound therapy

Aim of the studyNegative pressure wound therapy (NPWT) has become an established treatment modality when dealing with chronic and infected wounds. The underlying mechanism of action is still under discussion and remains controversial. Evidence exists showing rather hypoxic conditions as the main reason for the positive results and bacterial clearance. In an attempt to further explain the mechanism of action, we investigated oxygen levels within the foam interface of a NPWT device.Materials and methodsWe used an optical sensor based on the principle of dynamic fluorescence quenching and tested five different commonly available NPWT systems used during our daily clinical routine. All measurements were done in an in vitro experimental design for at least 24 h and multiple vacuum intensities were investigated.ResultsOxygen levels decreased as much as 22.8% and the amount of vacuum applied inversely correlated with the oxygen reduction. A stepwise increase in vacuum of 25 mmHg showed a linear mean drop of 2.75% per setting. All devices were able to maintain a constant level of negative pressure, and no significant difference between the various dressings was found (p > 0.05).ConclusionTherefore, oxygen levels are decreased within the foam of NPWT dressings, likely leading to oxygen deprivation effects in the underlying wound tissue.     

Prevalence of heterophoria in a population of school children in central China:the Anyang Childhood Eye Study

AIM:To investigate the prevalence of heterophoria and the relationship between heterophoria and refractive error in a school-based study conducted in central China.METHODS:A total of 23637 th-grade children were recruited into the cross-sectional school-based Anyang Childhood Eye Study(ACES)by cluster sampling method.Heterophoria was examined using alternate cover and cover-uncover testing.The Maddox rod and prism test were conducted at 33 cm and 6 m distance fixation.Uncorrected viual acuity(UCVA)and best-corrected viual acuity(BCVA)were recorded as logarithm of the minimum angle of resolution(logM AR)with cycloplegic autorefraction by administrating of Mydrin-P and 1.0%cyclopentolate.Hyperopia was defined as the spherical equivalent(SE)refraction of+0.50 D or greater,and higher hyperopia was defined as+2.00 D or greater.Emmetropia was defined as the SE refraction in the range of-0.49 to+0.49 D,and myopia was in the SE refraction range from-0.50 D to less.RESULTS:Totally 2260 students in grade 7 were examined.Response rate among eligible children was 95.64%.Totally 486 children,22.66%of the population,were diagnosed with heterophoria in which 479 were diagnosed with exophoria at near distance,and 6 with esophoria.Totally 89(4.15%)children were diagnosed with heterophoria in which 82 had exophoria,and 7 had esophoria at far distance.Exophoria was common at near fixation(22.33%).Myopia was examined to be related to exophoria at near distance(OR 3.03,95%CI 2.33-3.95)and far distance fixation(OR 1.90,95%CI 1.09-3.32).CONCLUSION:Exophoria is a predominant heterophoria for 7 th-grade junior school in central China.Significant associations are discovered between heterophoria and refractive error.Hyperopia is associated with esophoria,and myopia is associated with exophoria.     

如何使小梁切除术后眼压更可控

抗青光眼手术是青光眼治疗的主要方法之一。近年来,抗青光眼手术技术长足发展,微创手术层出不穷,患者及术者对手术预期也日益增高。然而,手术可控性不高导致术后疗效的可预测性不尽如人意。本文针对青光眼房水外引流手术中的小梁切除术,在分析其原理和局限性的基础上,指出手术效果的观察指标及术后眼压的调控方法,以期临床进一步开展相关研究,提高抗青光眼手术的疗效。     

About consistency of Solid's solubility data in supercritical CO2 and some thermodynamic properties estimation

In chemical industry, usual solvents are being replaced by supercritical fluids. Last few years, extraction by these environmentally benign solvents has had much attention and now is considered as the newest separation technology. However, developing new applications and improving existing ones is based on a set of thermodynamic and physical properties of pure solutes related to phase equilibrium for which experimental values cannot be found and consequently, there is an increase need for accurate estimates of these properties. This paper is interested firstly to a thermodynamic property which is the Krichevskii parameter and secondly to a thermophysical one which is the sublimation pressure. First parameter is considered as a governor of thermodynamic properties in binary dilute mixtures near the solvent's critical point and can be calculated from some rigorous relationships and in this paper a review and a new way for its estimation are presented based on consistency of solid's solubility data in supercritical fluids and dilute solution theory. Second parameter is considered as the predominant influencer on solubility in supercritical fluids and unavailability of its experimental values presents an obstacle to thermodynamic modeling of solubility data. For this reason and as a second step, in this paper we present a new manner for its estimation. Obtained results are relevant, very promising for each considered property and the methodology can be applied for other solutes with more complex structures as Pharmaceuticals (antibiotics, drugs, anti-inflammatories …), polycyclic aromatic hydrocarbons (PAHC) and dyestuffs.     

Fluctuaciones de presión intraocular en pacientes operados con implante de implantable collamer lens (ICL V4c). Seguimiento a 3 meses

IntroductionFluctuating elevated intraocular pressure (IOP) is one of the complications of an implantable collamer lens (ICL), and its alteration is a predictive factor for the development of glaucoma.Material and methodsA prospective, cross-sectional analytic study was conducted on patients suitable for ICL implantation. Complete clinical and biometric work-ups were performed, as well as night-time IOP curve, in supine position, with 4 determinations, in order to assess fluctuation, considering abnormal with a value higher than 5 mmHg. Patients underwent surgery with conventional technique and three months after the work-ups were repeated, including a night-time IOP curve to assess any changes in IOP fluctuations.ResultsA total of 31 eyes of 16 patients were studied. Mean IOP fluctuation in the preoperative assessment was 3.35 ± 2 mmHg, whereas the postoperative mean was 3.0 ± 2.2 mmHg, with the difference not being statistically significant. Visual acuity and capacity, as well as spheric equivalent did show a statistically significant improvement. There were 6 cases of complications, which were related to a higher vault and a greater ICL size. There was no relationship between these findings and the angle grade, pigment, and the level of training of the surgeon.ConclusionsThe effect of an ICL on IOP fluctuations, has been studied for the first time, which was found to be not statistically significant. As in previous publications, the procedure was safe and reproducible, adding the fact that the level of training of the surgeon is not a determining factor in these findings.     

间歇性负压封闭引流联合自体皮瓣原位弹性绷带加压包扎对溃疡期压疮疗效分析

目的探讨间歇性负压封闭引流(VSD)联合自体皮瓣原位弹性绷带加压包扎对III~Ⅳ期溃疡期压疮疗效的影响。方法选择2009年4月~2014年3月我科住院治疗的溃疡性压疮患者40例作为观察组,采用间歇性VSD联合自体皮瓣原位弹性绷带加压包扎的治疗方法。选择同期我科住院治疗的III~Ⅳ期溃疡性压疮患者25例作为对照组,采用常规换药联合自体皮瓣原位弹性绷带加压包扎的治疗方法。观察两组感染发生率、愈合情况及住院时间,并进行比较。结果观察组感染率为0,对照组感染率为76%,两组比较有显著性差异(P0.05);观察组皮瓣修复术前住院时间、术后住院时间、总住院时间较对照组明显缩短,两组比较有显著性差异差异(P0.05)。两组皮瓣面积、一期愈合、复发情况比较无显著性差异(P0.05)。结论间歇性VSD联合自体皮瓣原位弹性绷带加压包扎,能阻止溃疡期压疮创面感染,促进创面愈合,改善预后。     

对旋轴流通风机流场预测及两级电机功率匹配研究

对旋风机是矿井通风系统的重要组成部分，其安全稳定的运行是煤矿工人生命安全的保障。针对在长距离送风状态下，对旋风机风量显著减小、前后两级电机功率匹配难度加大的问题，依据流体动力学原理(Computational Fluid Dynamics，CFD)，采用对旋风机全域流体场数值模拟方法，对两级对旋叶轮性能与两级电动机性能的“线(点对点)”匹配进行研究。仿真结果揭示了对旋轴流通风机流场内部气流的真实流动规律以及两级电机轴功率匹配情况。将数值模拟结果和实验数据进行对比，验证该数值模拟方法的准确性，同时验证通过改变叶片安装角提高风机运行效率的可行性，为高性能对旋风机调速控制和节能控制提供理论依据。