36 research outputs found
Old Wine in New Bottles: Continuous Versus Intermittent Renal Replacement Therapy in the ICU
No full textRenal function in critically ill patients: assessment, replacement and histopathology. Towards personalized care
No full textPatients admitted to the Intensive Care Unit (ICU) frequently develop acute kidney injury (AKI). Changes in renal function are evaluated by blood levels of creatinine. Creatinine is a breakdown product of muscle cells which is eliminated by the kidneys via the urine. Renal function loss leads to accumulation of waste products and fluids, which may cause critical metabolic derangements. Patients with AKI may need renal replacement therapy (RRT) to correct these critical derangements. The use of RRT is frequently complicated by RRT circuit coagulation. AKI in the ICU mostly occurs due to sepsis, which is a life-threatening condition that arises when the body's response to an infection injures it's own tissues and organs. AKI was also frequently seen in COVID-19. Mechanisms leading to AKI are unclear in both sepsis and COVID-19. This PhD thesis illustrates that in ICU patients, renal function cannot reliably be assessed by blood creatinine due to muscle mass loss. Technical adjustments in RRT resulted in considerably less rapid RRT circuit coagulation. During the COVID-19 pandemic very rapid circuit coagulation was found, which we could substantially delay by the use of the combination of citrate and heparin for RRT circuit anticoagulation. Renal biopsies obtained after dead from patients with sepsis or COVID-19 indicated that the pathophysiological mechanisms for AKI in both entities might be different. In 93% of patients who died from COVID-19 chronic kidney disease (CKD) was found in biopsies indicating CKD is an important risk factor for a severe course of COVID-19
Stemple Pass (2012) et le projet Two Cabins : l’architecture de la solitude selon James Benning
No full textLe projet Two Cabins de James Benning gravite autour de la reproduction de deux cabanes dans l’espace de son jardin. La première est celle d’Henry David Thoreau, auteur transcendantaliste de Walden ou La vie dans les bois (1854). La seconde est celle de Theodore Kaczynski, aussi surnommé « Unabomber », écoterroriste états-unien et auteur d’un manifeste antitechnologique. Cet article se penche en particulier sur le film Stemple Pass (Benning, 2012), qui confronte les écrits de Kaczynski à la reproduction de son habitat.James Benning’s project Two Cabins revolves around the reconstruction of two cabins in his own yard (or garden). The first belongs to Henry David Thoreau, the transcendentalist author of Walden; or, Life in the Woods (1854). The second is that of Theodore Kaczynski, an ecoterrorist also known as “the Unabomber” who wrote an anti-technological manifesto. This article focuses on Stemple Pass, Benning’s 2012 film that juxtaposes Kaczynski’s writings and the reconstruction of his cabin
GEOWALL® as a Quay wall
No full textBank protections are currently constructed with stone, wood, concrete and steel. NETICS has introduced a sustainable and commercially very attractive alternative called the GEOWALL. The goal of this study is to find a viable field of application within the quay structures by considering the arising challenges of a larger scale wall. Additionally several potential design improvements are described to cope with the challenges. The GEOWALL could fail due to sliding, overturning, exceeding internal stresses, large deformations, vertical instability, overall instability and piping. The safety of the structure will be assessed with predefined general factors of safety and permissible internal stresses, these are the test values. The safety for sliding, overturning, large deformations, vertical stability and piping is calculated with an analytical method. The safety for overall stability, internal strength and large deformations is calculated with a finite element method. There are two main variables in the analyses: the retaining height and the type of soil. The retaining height varies between one and five metres. The soils are simplified to sand, clay and peat. From the results of the analytical analysis and the finite element analysis it can be concluded that sand-GEOWALLs on sand between one and three metres and clay-GEOWALLs on clay between one and three metres are the most viable scenarios for a larger scale GEOWALL with current design. For GEOWALL quay walls larger than three metres and peat-GEOWALLs on peat suitable design improvements are required to meet the stringent safety requirements. The design improvements should be able to limit the possibility of failure due to sliding, overturning and failure trough large deformations. There are three categories of potential improvements: material improvements, geometrical design improvements and structural design improvements. The embedded wall is expected to be the most promising geometrical design improvement. Adding a drainage system is expected to be the most promising structural design improvement at this moment. It is recommended to study the effects and efficiency of the proposed design improvements in future research. It is also recommended for NETICS to continue their research on the strength and resistance of different GEOWALL types and on the influence of every possible load. In case of a GEOWALL design for a specific location it is recommended to determine the safety factors for that specific location and to check the analytical results with more advanced modelling programmes. Lastly it is recommended to consider not only the technical aspects, but also the practical and commercial aspects if one is investigating the design improvements.Hydraulic EngineeringCivil Engineering and Geoscience
Towards real-time identification of brain tumors by integrating diffuse reflectance spectroscopy in a neurosurgical instrument
No full textBrain tumors account for approximately just 2% of all cancers worldwide, but have a noticeable impact on cancer morbidity and mortality. Removal of brain tumors poses a big challenge for neurosurgeons, pediatricians and neuro-oncologists. An important aspect of this challenge is to adequately differentiate between tumor tissue and healthy brain tissue. Tumors that are located within the eloquent cortex (functional brain cortex and major white matter fiber tracts) pose a particular surgical challenge due to the high risk of postoperative neurological deficits. Together with the In-Body Systems department of Philips Research and the Karolinska Institute in Sweden, the Delft University of Technology is participating in a new research focusing on adding diffuse reflectance spectroscopy in a neurosurgical instrument that can aid in better identifying the brain tumor margin. Previous research has used diffuse reflectance spectroscopy or a combination of diffuse reflectance and tissue fluorescence from endogenous (e.g., NADPH), exogenous (e.g., fluorescein), or exogenously induced fluorophores (e.g., PpIX) to identify spectral differences between healthy brain tissue and brain tumor tissue over a range of 400-900 nm. This master thesis presents the spectral differences between healthy and tumorous tissue over a range of 400-1600 nm, while using a spectroscopic tool, to better determine the demarcation of brain tumor margins with increased accuracy. The differences in optical characteristics in healthy brain tissue (i.e. white and gray matter) and human brain tumor tissue were identified. Furthermore, it was investigated whether the optical characteristics can provide a means to quantify the distinction between healthy and brain tumor tissue. Clear differences were found in the spectra between the different tissues. In the visible region higher values for the absorption coefficient were identified as indicators for tumor tissues. In the near infrared region clear distinctions in the diffuse reflectance spectra were observed between gray matter, tumor tissue and white matter, with gray matter presenting the highest value. The reduced scattering coefficient showed especially a clear distinction for white matter, presenting the highest values, compared to gray matter and tumor tissue. This was in line with the measurements of the scattering parameters and the fat fraction, with white matter presenting the highest value which can be explained due to its myelinated axons. For the other investigated parameters, an increased level of blood concentration and lower levels of StO2 were indicated as biomarkers for the tumor tissues. However, both physiological parameters are likely to change from in vivo to ex vivo settings which require that they should be investigated in in vivo experiments first before statements about their reliability can be made. The study was followed with a clinical workflow analysis, to identify the most promising neurosurgical instrument used during craniotomy in which diffuse reflectance spectroscopy can be integrated. Based on observations at brain tumor surgeries, open interviews with neurosurgeons and an investigation on several instruments, the suction cannula was found to be the most promising neurosurgical instrument to combine with diffuse reflectance spectroscopy. Finally, a prototype was designed and tested. In addition, it was investigated whether different amounts of suction power had an influence on the accuracy of the measured spectra while performing measurements with the prototype on healthy pig brain tissue. Overall, it can be concluded that spectral differences between healthy and tumorous tissue can be observed with the prototype and future research should increase the amount of data to verify these results. Furthermore, in vivo measurements should indicate whether these findings are consistent when the physiology of the tissues changes
