Investigation of an electrolysis system with boron-doped diamond anode and gas diffusion cathode to remove water micropollutants.

Using electrolysis systems to degrade organics in wastewater encourages this technique to remove micropollutants (MPs) in different types of water. In this work, a cell consisting of an anode as a boron-doped diamond (BDD) electrode combined with a gas diffusion (GDE) cathode without a separator showed that MPs degradation can be effectively achieved. Investigating different operating parameters, it was stated that applying a low current density (2 mA/cm2) and setting the Reynolds number of the electrolyte flow through the cell at the laminar range raised the treatment time by 3-fold at the same energy demand. This arrangement increased the MPs removal. Some substances like diclofenac were removed up to 84% at a longer treatment time of 180 min coupled with an increase in energy demand. The results at the mentioned parameters indicated an adequate generation rate of radicals needed to remove MPs and the oxidation reactions were promoted. The results show high potential to the investigated electrolysis system in removing MPs in wastewater under considering the need for further reduction of the energy demand.

Determination of the through-plane profile of vanadium species in hydrated Nafion studied with micro X-ray absorption near-edge structure spectroscopy - proof of concept.

Vanadium-ion transport through the polymer membrane results in a significant decrease in the capacity of vanadium redox flow batteries. It is assumed that five vanadium species are involved in this process. Micro X-ray absorption near-edge structure spectroscopy (micro-XANES) is a potent method to study chemical reactions during vanadium transport inside the membrane. In this work, protocols for micro-XANES measurements were developed to enable through-plane characterization of the vanadium species in Nafion 117 on beamline P06 of the PETRA III synchrotron radiation facility (DESY, Hamburg, Germany). A Kapton tube diffusion cell with a diameter of 3 mm was constructed. The tube diameter was chosen in order to accommodate laminar flow for cryogenic cooling while allowing easy handling of the cell components by hand. A vertical step size of 2.5 µm and a horizontal step size of 5 µm provided sufficient resolution to resolve the profile and good statistics after summing up horizontal rows of scan points. The beam was confined in the horizontal plane to account for the waviness of the membrane. The diffusion of vanadium ions during measurement was inhibited by the cryogenic cooling. Vanadium oxidation, e.g. by water radiolysis (water percentage in the hydrated membrane ∼23 wt%), was mitigated by the cryogenic cooling and by minimizing the dwell time per pixel to 5 ms. Thus, the photo-induced oxidation of V3+ in the focused beam could be limited to 10%. In diffusion experiments, Nafion inside the diffusion cell was exposed on one side to V3+ electrolyte and on the other side to VO2+. The ions were allowed to diffuse across the through-plane orientation of the membrane during one of two short defrost times (200 s and 600 s). Subsequent micro-XANES measurements showed the formation of VO2+ from V3+ and VO2+ inside the water body of Nafion. This result proves the suitability of the experimental setup as a powerful tool for the determination of the profile of vanadium species in Nafion and other ionomeric membranes.

Influence of Water Hardness and Complexing Agents on Electrochemical Hydrogen Peroxide Generation.

Recently, many studies have been published regarding electrochemical oxygen reduction reaction for generating hydrogen peroxide (H2O2) using gas diffusion electrodes (GDEs) for various applications. Sodium salts solved in deionized water were usually used as supporting electrolytes. In technical applications, however, tap water-based electrolytes with hardeners are particularly relevant and have only been considered in a few studies to date. In this work, we investigated the influence of hardeners on H2O2-generation at 150 mA cm-2 and were able to show that scaling occurs predominantly on the GDE-surface and not in its pore structure. With the novel method in electrochemical synthesis by using complexing agents to bind hardeners, we were able to significantly reduce the scaling. Even after 10 h of operation, the reactor still achieves a faradaic efficiency (FE) of above 70 % (>67 mg h-1 cm-2), comparable to the experiments without hardeners and complexing agents in the electrolyte. Furthermore, we demonstrate that the complexing agents are not electrochemically converted at the carbon-based GDE and behave inertly. If the cell is operated with complexing agents and rinsed with acidic liquid (anolyte) between batches, scaling can be completely avoided.

Three years of neurosurgical experience in a multinational field hospital in northern Afghanistan.

BACKGROUND: Since July 2007, neurosurgical services have been continuously available in a multinational Role 3 field hospital in Mazar-e-Sharif (MeS), Afghanistan. In this paper, we analyse a 3-year neurosurgical caseload experience. METHODS: We retrospectively analysed the neurosurgical caseload at a Role 3 medical treatment facility in northern Afghanistan between October 2007 and October 2010. The cases were divided into acute, urgent and elective procedures and into cranial, spinal, peripheral nerve and miscellaneous surgeries. RESULTS: A total of 190 surgeries were performed. Of these, 50 operations (26.3%) were acute procedures that were conducted to save lives or preserve neurological function. In addition, operations included 47 urgent (24.7%) and 93 elective (49%) procedures. There were 58 cranial surgeries (30.5%), 113 spinal surgeries (59.5%), 11 peripheral nerve surgeries (5.8%), and 8 miscellaneous surgeries (4.2%). Surgical treatment was provided to 13 International Security Assistance Force (ISAF) soldiers (6.8%), 22 members of the Afghan National Security Forces (11.6%), and 155 Afghan civilians (81.6%). CONCLUSIONS: The primary mission of the field hospital is to provide sick, injured or wounded ISAF personnel with medical and surgical care, the outcome of which must correspond to standards prevailing in Germany. Only a very small number of neurosurgical operations performed in MeS met the criteria established by this mission statement and by the modern principles of damage-control wartime surgery. This is completely different from the experience reported by other ISAF nations in eastern and southern Afghanistan.

A New Reactor Concept for Single-Chamber Microbial Fuel Cells and Possible Anti-Fouling Strategies for Long-Term Operation.

Microbial fuel cells are a promising technology for future wastewater treatment, as it allows cleaning and power generation simultaneously. The bottleneck of microbial fuel cells is often its cathodes because they determine the power output. Gas diffusion electrodes might overcome this bottleneck due to their low production costs and high oxygen reduction rates. However, biofilm formation on the gas diffusion electrodes reduces their performance over time. In this work, a new reactor design of the microbial fuel cell using rotating gas diffusion electrodes is presented. The biofilm growth on the electrode during operation was observed and its effect on the performance of the microbial fuel cell was examined. In addition, different antifouling strategies were investigated over a period of 80 days. It was found that already after 7 days of operation a complete biofilm had grown on an untreated gas diffusion electrode. However, this does not seem to affect the performance of the cells in the beginning. Differences in the performance of the reactors with and without an antifouling strategy only become apparent from day 15 onwards. The use of UV radiation and antibacterial membranes leads to the best results with maximum power densities of approx. 200 mW m-2 while the untreated microbial fuel cell only achieves a maximum power density of approx. 20 mW m-2.

Biomarker context-of-use: how organizational design can impact the implementation of the appropriate biomarker assay strategy.

Since 2011, the European Bioanalysis Forum has been discussing the topic of context-of-use for biomarker assays, in support of a cross-industry implementation of its principles. The discussions have led to the acknowledgement of the challenges that we face as an industry in implementing these principles. In addition to scientific recommendations, the European Bioanalysis Forum has addressed these challenges by providing recommendations on organizational design, and what works in both sponsor and contract research organizations, to support and enable context-of-use across biomarker strategies. Here, we highlight the key considerations for organizational design to help ensure that biomarker assays are characterized and validated according to the right context-of-use, to ensure that the right decisions based on the biomarker data can be made during drug development.

Arachnoscopy: a special application of spinal intradural endoscopy.

OBJECT: The microsurgical removal of obstructions to CSF flow is the treatment of choice in the surgical management of intradural arachnoid cysts. Cardiac-gated phase-contrast MR imaging is an effective tool for the primary diagnosis and localization of arachnoid cysts. Microsurgery, however, does not lend itself to assessments of further adhesions beyond the borders of the exposed area. The use of a thin endoscope allows surgeons to assess intraoperatively whether the exposure is wide enough. METHODS: Between 2006 and 2010, a single neurosurgeon performed 31 consecutive microsurgical procedures with endoscopic assistance in 28 patients with spinal arachnoid adhesions. A MurphyScope endoscope was used for this purpose. The CSF flow was studied before and after surgery in all patients by using phase-contrast MR imaging in the region of the craniocervical junction, the cervical spine, the thoracic spine, and the lumbar spine. RESULTS: In all 31 procedures, CSF flow obstructions were detected at the level identified by phase-contrast MR imaging. In 29 procedures, image quality was sufficient for an inspection of the adjacent subarachnoid space. In 6 cases, the surgeon detected further adhesions that obstructed CSF flow in the adjacent subarachnoid space that were not visualized with the microscope. In all cases, these adhesions were identified and removed during microsurgery. CONCLUSIONS: Arachnoscopy is a helpful adjunct to microsurgery and can be performed safely and easily. It allows the surgeon to detect further adhesions in the subarachnoid space that would remain undetected by microscopy alone.

Treatment of unresectable skull base meningiomas with somatostatin analogs.

OBJECT: The standard surgical treatment for meningiomas is total resection, but the complete removal of skull base meningiomas can be difficult for several reasons. Thus, the management of certain meningiomas of the skull base--for example, those involving basal vessels and cranial nerves--remains a challenge. In recent reports it has been suggested that somatostatin (SST) administration can cause growth inhibition of unresectable and recurrent meningiomas. The application of SST and its analogs is not routinely integrated into standard treatment strategies for meningiomas, and clinical studies proving growth-inhibiting effects do not exist. The authors report on their experience using octreotide in patients with recurrent or unresectable meningiomas of the skull base. METHODS: Between January 1996 and December 2010, 13 patients harboring a progressive residual meningioma (as indicated by MR imaging criteria) following operative therapy were treated with a monthly injection of the SST analog octreotide (Sandostatin LAR [long-acting repeatable] 30 mg, Novartis). Eight of 13 patients had a meningioma of the skull base and were analyzed in the present study. Postoperative tumor enlargement was documented in all patients on MR images obtained before the initiation of SST therapy. All tumors were benign. No patient received radiation or chemotherapy before treatment with SST. The growth of residual tumor was monitored by MR imaging every 12 months. RESULTS: Three of the 8 patients had undergone surgical treatment once; 3, 2 times; and 2, 3 times. The mean time after the last meningioma operation (before starting SST treatment) and tumor enlargement as indicated by MR imaging criteria was 24 months. A total of 643 monthly cycles of Sandostatin LAR were administered. Five of the 8 patients were on SST continuously and stabilized disease was documented on MR images obtained in these patients during treatment (median 115 months, range 48-180 months). Three of the 8 patients interrupted treatment: after 60 months in 1 case because of tumor progression, after 36 months in 1 case because of side effects, and after 36 months in 1 case because the health insurance company denied cost absorption. CONCLUSIONS: Although no case of tumor regression was detected on MR imaging, the study results indicated that SST analogs can arrest the progression of unresectable or recurrent benign meningiomas of the skull base in some patients. It remains to be determined whether a controlled prospective clinical trial would be useful.

Standard and cardiac-gated phase-contrast magnetic resonance imaging in the clinical course of patients with Chiari malformation Type I.

OBJECT: The causal treatment of Chiari malformation Type I (CM-I) consists of removing the obstruction of CSF flow at the level of the foramen magnum. Cerebrospinal fluid flow can be visualized using dynamic phase-contrast MR imaging. Because there is only a paucity of studies evaluating CSF dynamics in the region of the spinal canal on the basis of preoperative and postoperative measurements, the authors investigated the clinical usefulness of cardiacgated phase-contrast MR imaging in patients with CM-I. METHODS: Ninety patients with CM-I underwent preoperative MR imaging of CSF pulsation. Syringomyelia was present in 59 patients and absent in 31 patients. Phase-contrast MR imaging of the entire CNS was used to investigate 22 patients with CM-I before surgery and after a mean postoperative period of 12 months (median 12 months, range 3-33 months). In addition to the dynamic studies, absolute flow velocities, the extension of the syrinx, and tonsillar descent were also measured. RESULTS: The changes in pulsation were highly significant in the region of the (enlarged) cistern (p = 0.0005). Maximum and minimum velocities (the pulsation amplitude) increased considerably in the region where the syrinx was largest in diameter. The changes of pulsation in these patients were significant in the subarachnoid space in all spinal segments but not in the syrinx itself and in the central canal. CONCLUSIONS: The demonstration of CSF flow pulsation can contribute to assessments of surgical outcomes. The results presented here, however, raise doubts about current theories on the pathogenesis of syringomyelia.

Noninvasive intracranial pressure measurement using infrasonic emissions from the tympanic membrane.

OBJECTIVE: We investigated whether ICP can be assessed by measuring infrasonic emissions from the tympanic membrane. METHODS: An increase in ICP was induced in 22 patients with implanted ICP pressure sensors. ICP waveforms that were obtained invasively and continuously were compared with infrasonic emission waveforms. In addition, the noninvasive method was used in a control group of 14 healthy subjects. RESULTS: In a total of 83 measurements, the changes in ICP that were observed in response to different types of stimulation were detected in the waveforms obtained noninvasively as well as in those acquired invasively. Low ICP was associated with an initial high peak and further peaks with smaller amplitudes. High ICP was associated with a marked decrease in the number of peaks and in the difference between the amplitudes of the initial and last peaks. The assessment of infrasonic emissions, however, does not yet enable us to provide exact figures. CONCLUSION: It is conceivable that the assessment of infrasonic emissions will become suitable both as a screening tool and for the continuous monitoring of ICP in an intensive care environment.

Continuous preparation of carbon-nanotube-supported platinum catalysts in a flow reactor directly heated by electric current.

In this contribution we present for the first time a continuous process for the production of highly active Pt catalysts supported by carbon nanotubes by use of an electrically heated tubular reactor. The synthesized catalysts show a high degree of dispersion and narrow distributions of cluster sizes. In comparison to catalysts synthesized by the conventional oil-bath method a significantly higher electrocatalytic activity was reached, which can be attributed to the higher metal loading and smaller and more uniformly distributed Pt particles on the carbon support. Our approach introduces a simple, time-saving and cost-efficient method for fuel cell catalyst preparation in a flow reactor which could be used at a large scale.

Polymer Membranes for All-Vanadium Redox Flow Batteries: A Review.

Redox flow batteries such as the all-vanadium redox flow battery (VRFB) are a technical solution for storing fluctuating renewable energies on a large scale. The optimization of cells regarding performance, cycle stability as well as cost reduction are the main areas of research which aim to enable more environmentally friendly energy conversion, especially for stationary applications. As a critical component of the electrochemical cell, the membrane influences battery performance, cycle stability, initial investment and maintenance costs. This review provides an overview about flow-battery targeted membranes in the past years (1995-2020). More than 200 membrane samples are sorted into fluoro-carbons, hydro-carbons or N-heterocycles according to the basic polymer used. Furthermore, the common description in membrane technology regarding the membrane structure is applied, whereby the samples are categorized as dense homogeneous, dense heterogeneous, symmetrical or asymmetrically porous. Moreover, these properties as well as the efficiencies achieved from VRFB cycling tests are discussed, e.g., membrane samples of fluoro-carbons, hydro-carbons and N-heterocycles as a function of current density. Membrane properties taken into consideration include membrane thickness, ion-exchange capacity, water uptake and vanadium-ion diffusion. The data on cycle stability and costs of commercial membranes, as well as membrane developments, are compared. Overall, this investigation shows that dense anion-exchange membranes (AEM) and N-heterocycle-based membranes, especially poly(benzimidazole) (PBI) membranes, are suitable for VRFB requiring low self-discharge. Symmetric and asymmetric porous membranes, as well as cation-exchange membranes (CEM) enable VRFB operation at high current densities. Amphoteric ion-exchange membranes (AIEM) and dense heterogeneous CEM are the choice for operation mode with the highest energy efficiency.

Characterization of Dimeric Vanadium Uptake and Species in Nafion™ and Novel Membranes from Vanadium Redox Flow Batteries Electrolytes.

A core component of energy storage systems like vanadium redox flow batteries (VRFB) is the polymer electrolyte membrane (PEM). In this work, the frequently used perfluorosulfonic-acid (PFSA) membrane Nafion™ 117 and a novel poly (vinylidene difluoride) (PVDF)-based membrane are investigated. A well-known problem in VRFBs is the vanadium permeation through the membrane. The consequence of this so-called vanadium crossover is a severe loss of capacity. For a better understanding of vanadium transport in membranes, the uptake of vanadium ions from electrolytes containing Vdimer(IV-V) and for comparison also V(II), V(III), V(IV), and V(V) by both membranes was studied. UV/VIS spectroscopy, X-ray absorption near edge structure spectroscopy (XANES), total reflection X-ray fluorescence spectroscopy (TXRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and micro X-ray fluorescence spectroscopy (microXRF) were used to determine the vanadium concentrations and the species inside the membrane. The results strongly support that Vdimer(IV-V), a dimer formed from V(IV) and V(V), enters the nanoscopic water-body of Nafion™ 117 as such. This is interesting, because as of now, only the individual ions V(IV) and V(V) were considered to be transported through the membrane. Additionally, it was found that the Vdimer(IV-V) dimer partly dissociates to the individual ions in the novel PVDF-based membrane. The Vdimer(IV-V) dimer concentration in Nafion™ was determined and compared to those of the other species. After three days of equilibration time, the concentration of the dimer is the lowest compared to the monomeric vanadium species. The concentration of vanadium in terms of the relative uptake λ = n(V)/n(SO3) are as follows: V(II) [λ = 0.155] > V(III) [λ = 0.137] > V(IV) [λ = 0.124] > V(V) [λ = 0.053] > Vdimer(IV-V) [λ = 0.039]. The results show that the Vdimer(IV-V) dimer needs to be considered in addition to the other monomeric species to properly describe the transport of vanadium through Nafion™ in VRFBs.

Recommendations and discussion points on immunogenicity, biomarkers, automation/technology and protein-MS from the 2021 European Bioanalysis Forum Focus Workshops.

During the first half of 2021, and due to the SARS-CoV-2 pandemic preventing in-person meetings, the European Bioanalysis Forum organized four workshops as live interactive online meetings. The themes discussed at the workshops were carefully selected to match the cyberspace dynamics of the meeting format. The first workshop was a training day on challenges related to immunogenicity. The second one focused on biomarkers and continued the important discussion on integrating the principles of Context of Use (CoU) in biomarker research. The third workshop was dedicated to technology, that is, cutting-edge development in cell-based and ligand-binding assays and automation strategies. The fourth was on progress and the continued scientific and regulatory challenges related to peptide and protein analysis with MS. In all four workshops, the European Bioanalysis Forum included a mixture of scientific and regulatory themes, while reminding the audience of important strategic aspects and our responsibility toward the patient.

Management of neurotrauma by surgeons and orthopedists in a military operational setting.

There is a considerable discrepancy between the potential demand for neurosurgeons and the actual availability of such specialists not only in civilian settings but even more so in military operational environments. For this reason, the Department of Neurosurgery at the German Armed Forces Hospital in Ulm conducts courses for surgeons and orthopedists on the management of patients with neurotrauma. Twelve such courses have already taken place. Each course lasts 1 week. Participants can expect to gain the theoretical knowledge and practical skills they need to provide initial surgical care for patients with traumatic brain injuries and/or spinal trauma. Surgical techniques are practiced above all in pig and human cadavers. At the end of the course, participants with previous surgical knowledge should be able to independently perform a craniotomy, from the planning of the procedure to the closure of the wound. Former course participants have successfully used their neurosurgical knowledge in countries of deployment where they managed patients during teleconsultation sessions and helped repatriate, or even provided surgical treatment to, patients with traumatic brain injuries. In these situations, it was particularly helpful when the physician deployed abroad and the neurosurgeon in Germany knew each other personally. In the future, efforts will be made to combine telemedicine and neuronavigation in an attempt to further improve direct support for physicians under military deployment conditions.

German military neurosurgery at home and abroad.

For many years, the experience of neurosurgeons from the German Armed Forces was limited to the peacetime care of patients in Germany. In 1995, German military neurosurgeons were deployed abroad for the first time. Since the beginning of the International Security Assistance Force mission, there has been a rapidly increasing number of opportunities for military neurosurgeons to broaden their experience during deployments abroad. Since the first deployment of a neurosurgeon to the German field hospital in Mazar-e-Sharif, Afghanistan, a total of 140 neurosurgical procedures have been performed there. Sixty-four surgeries were performed for cranial or spinal neurotrauma management. During the entire period, only 10 International Security Assistance Force members required acute or urgent neurosurgical interventions. The majority of neurosurgical procedures were performed in Afghan patients who received acute and elective treatment whenever the necessary infrastructure was available in the field hospital. Fifteen patients from the Afghan National Army and Police and 115 local patients underwent neurosurgery. Sixty-two procedures were carried out under acute or urgent conditions, and 78 operations were elective.

Update to the European Bioanalysis Forum recommendation on biomarkers assays; bringing context of use into practice.

In 2012, the European Bioanalysis Forum published a recommendation on biomarker method development and the bioanalysis of biomarkers in support of drug development. Since then, there has been significant discussion on how to bring the topic of context of use of biomarker assays to the forefront so that the purpose of the assay, the use of the data and the decisions being made with the data are well defined and clearly understood, not just by the bioanalytical scientist, but across all stakeholders. Therefore, it is imperative that discussions between the bioanalytical laboratory and the end users of the data happen early (and regularly) in the drug development process to enable the right assays to be developed and appropriately validated to generate the correct data and allow suitable decisions to be made. This updated refinement to the previous European Bioanalysis Forum recommendation will highlight the items to consider when discussing context of use for biomarker assay development and validation, thus enabling the correct conversations to occur and the move away from the misapplication of PK assay validation criteria to biomarker assays.

Flow through reactors for organic chemistry: directly electrically heated tubular mini reactors as an enabling technology for organic synthesis.

Until recently traditional heating in organic chemistry has been done with oil heating baths or using electric heat exchangers. With the advent of microwave equipment, heating by microwaves was rapidly introduced as standard method in organic chemistry laboratories, mainly because of the convenient possibility to operate at high temperature accompanied by accelerated reaction rates. In the present contribution we discuss the method of heating small, continuously operated reactors by passing electric current directly through the reactor wall as an enabling technology in organic chemistry. The benefit of this method is that the heat is generated directly inside the reactor wall. By this means high heating rates comparable to microwave ovens can be reached but at much lower cost for the equipment. A tool for the comparison of microwave heating and traditional heating is provided. As an example kinetic data for the acid catalyzed hydrolysis of methyl formate were measured using this heating concept. The reaction is not only a suitable model but also one of industrial importance since this is the main production process for formic acid.

Preparation of Polymer Electrolyte Membranes via Radiation-Induced Graft Copolymerization on Poly(ethylene-alt-tetrafluoroethylene) (ETFE) Using the Crosslinker N,N'-Methylenebis(acrylamide).

Polymer electrolyte membranes (PEM) prepared by radiation-induced graft copolymerization are investigated. For this purpose, commercial poly(ethylene-alt-tetrafluoroethylene) (ETFE) films were activated by electron beam treatment and subsequently grafted with the monomers glycidyl methacrylate (GMA), hydroxyethyl methacrylate (HEMA) and N,N'-methylenebis(acrylamide) (MBAA) as crosslinker. The target is to achieve a high degree of grafting (DG) and high proton conductivity. To evaluate the electrochemical performance, the PEMs were tested in a fuel cell and in a vanadium redox-flow battery (VRFB). High power densities of 134 mW∙cm-2 and 474 mW∙cm-2 were observed, respectively.

The Hakim programmable valve: reasons for reprogramming failures.

OBJECT: In patients with hydrocephalus, the pressure settings of a Medos Hakim programmable valve may require adjustments even months after implantation. In some cases, however, adjustment proves to be impossible. The object of this study was to illuminate the reasons for reprogramming failures. METHODS: Data pertaining to the authors' experience with programmable valves at their clinic were obtained through retrospective review of patient records from 1992 to 1998 and prospectively collected from 1998 to 2006. Between 1992 and 2006, 585 Medos Hakim programmable valves were implanted at the authors' center, and reprogramming failure was observed in 12 of these 585 cases. The authors investigated and recorded the reasons for reprogramming failure. In cases in which the valves had to be explanted, the valves were returned to the manufacturer for further investigation and the results were recorded. RESULTS: In three of the 12 cases of reprogramming failure, the pressure settings could eventually be adjusted by placing the transmitter upside down against the flow direction. In the remaining nine cases, the valve had to be removed, yielding a rate of valve explantation of approximately 1.5% in this series. In two of these nine cases, the valve was found to be rotated longitudinally along its axis. In two cases the ratchet wheel had become loose and in one the radiopaque marker had become dislodged from the baseplate. Extensive deposits were identified macroscopically and microscopically within four explanted valves. CONCLUSIONS: The reasons for failed reprogramming of Codman Medos Hakim valves as described in this article have not been mentioned in the literature so far. Failure of adjusting the pressure setting is a very rare event in a Medos Hakim programmable valve. The programming and adjustment mechanism appears to be very reliable. Valve replacement was required due to failed reprogramming in only a few cases.