Evidence based guidelines for complex regional pain syndrome type 1

Background: Treatment of complex regional pain syndrome type I (CRPS-I) is subject to discussion. The purpose of this study was to develop multidisciplinary guidelines for treatment of CRPS-I. Method: A multidisciplinary task force graded literature evaluating treatment effects for CRPS-I according to their strength of evidence, published between 1980 to June 2005. Treatment recommendations based on the literature findings were formulated and formally approved by all Dutch professional associations involved in CRPS-I treatment. Results: For pain treatment, the WHO analgesic ladder is advised with the exception of strong opioids. For neuropathic pain, anticonvulsants and tricyclic antidepressants may be considered. For inflammatory symptoms, free-radical scavengers (dimethylsulphoxide or acetylcysteine) are advised. To promote peripheral blood flow, vasodilatory medication may be considered. Percutaneous sympathetic blockades may be used to increase blood flow in case vasodilatory medication has insufficient effect. To decrease functional limitations, standardised physiotherapy and occupational therapy are advised. To prevent the occurrence of CRPS-I after wrist fractures, vitamin C is recommended. Adequate perioperative analgesia, limitation of operating time, limited use of tourniquet, and use of regional anaesthetic techniques are recommended for secondary prevention of CRPS-I. Conclusions: Based on the literature identified and the extent of evidence found for therapeutic interventions for CRPS-I, we conclude that further research is needed into each of the therapeutic modalities discussed in the guidelines

Is the ADA/EASD algorithm for the management of type 2 diabetes (January 2009) based on evidence or opinion? A critical analysis

The ADA and the EASD recently published a consensus statement for the medical management of hyperglycaemia in patients with type 2 diabetes. The authors advocate initial treatment with metformin monotherapy and lifestyle modification, followed by addition of basal insulin or a sulfonylurea if glycaemic goals are not met (tier 1 recommendations). All other glucose-lowering therapies are relegated to a secondary (tier 2) status and only recommended for selected clinical settings. In our view, this algorithm does not offer physicians and patients the appropriate selection of options to individualise and optimise care with a view to sustained control of blood glucose and reduction both of diabetes complications and cardiovascular risk. This paper critically assesses the basis of the ADA/EASD algorithm and the resulting tiers of treatment options

Investigation into quantitative visualisation of suffusion

Suffusion is the process whereby seepage water removes fine grains from a soil, which can result in failure of the soil body. This poses a risk for structures founded on soils that are subjected to large hydraulic gradients, such as encountered near hydraulic dams or river levees. Currently, most experimental work on this topic is geared towards quantifying, both the hydraulic gradient at which suffusion initiates, and the flux of eroded material. The reported values vary widely among experiments. The variation in the results can be explained by taking into account the effect of different experimental conditions. The flux of eroded material is the result of the interplay between particle erosion and filtration within the soil. Visualisation experiments allow for the direct observation of this. The effect of experimental conditions on the individual mechanisms of filtration and erosion, as well as the interaction between these, can be studied. Thereby, visualisation experiments complement methods targeted at quantifying the mass flux leaving the sample. In this work, the movement of fine grains and the resulting change in the structure of the sample are studied. Common laboratory equipment is used to design a visualisation experiment. The acquired images are analysed using three different quantitative image analysis techniques, with the objective of gaining further insight into the mechanism of suffusion. Particle image velocimetry (PIV) is an Eulerian method that is applied to determine velocity fields in fluid mechanics and granular flows. During suffusion, the velocity field is discontinuous; fine grains move whilst the coarse grains form a relatively fixed skeleton. This makes PIV less useful for the study of suffusion. To determine the displacement of individual particles, a Lagrangian method of particle tracking is considered. In the experimental setup used, fine grains are only tracked for a short length of time. This is due to both the large particle displacement between successive images, and the fact that other grains obscure the tracked particles from the camera. These difficulties can be remediated by improvement of the experimental procedure; the former by a higher acquisition rate, and the latter by use of a transparent granular medium where only the tracer particles are visible. With the apparatus used in this work, the temporal resolution is such that particle displacement cannot be studied unambiguously. Instead, a method of image subtraction (IS) is used that is geared towards quantifying the amount of material that moves. This yields data that can be interpreted to study both how much movement occurs, and where the movement occurs. Furthermore, IS is used to quantify the total change in the structure of the soil sample. Tests indicate that the load history plays an important role during suffusion. Erosion and filtration cause the soil structure to change, which has a direct effect on further particle transport in the sample. Therefore, the relation between three parameters: the number of moving particles, the location where they move, and the progression of the experiment, is key to understanding the process of suffusion. This is studied by plotting the movement in a 1D section of the sample over time. It can be concluded that visualisation experiments complement existing outflow experiments to study suffusion. The results of IS can be related to conceptual models that are currently used to describe erosion and filtration processes; these concepts are applicable also to the process of suffusion. Improvement of the experimental setup is required to establish whether the observations reported in this work have a general validity.Section Geo-EngineeringCivil Engineering and Geoscience

Viewing fluid flow inside a granular medium

This paper describes preliminary tests from a ‘transparent soil permeameter’ that has been developed to study the mechanisms that occur during internal erosion in filter materials for embankment dams. The laboratory-based experiments utilise an optical approach where glass particles are used in place of soil, and optically matched oil is used in place of water. The refractive index matching of the fluid and solid enables a two-dimensional “slice” or plane of particles and fluid to be viewed inside the permeameter, away from its walls via a laser sheet and captured by digital camera. The developed set up has already been tested and showed that optically matched glass and oil can behave similarly to soil and water materials as used in previous laboratory testing. In this study we present a flow characterization within a refractive index matched medium made of glass beads. To this end a small amount of fluid tracers is seeded inside the fluid and the velocity field inside the porous media is obtained using PIV measurements

Investigation of the coarse sand barrier against backward erosion piping

Backwards erosion piping poses a risk for levees or embankments founded on an aquifer cov-ered by a blanket layer. Piping occurs when particles are eroded from the aquifer at an interruption of the blanket layer on the landward side, and a pipe is eroded that progresses upstream. When the pipe reaches the outside water body, excessive erosion can lead to embankment collapse. The coarse sand barrier (CSB) is an innovative measure to stop piping. It consists of a coarse grained filter that is placed in the top of the aquifer, which prevents pipes from progressing upstream. This paper addresses the hypothesis that the local horizontal gradient at the interface between the barrier and the pipe determines whether the pipe can progress into the barrier, and that the ‘critical’ gradient is a material property of the barrier, independent of scale or background sand, based on experimental results and numerical modelling