Endovascular treatment of iatrogenic central vein stenosis and occlusion in patients undergoing haemodialysis : a two-year follow-up

Objectives: The objective of our report was to present the results of two-year follow-up of endovascular treatment of central venous occlusive disease in haemodialysis patients. Material and methods: Eighty-one consecutive patients with central venous occlusive disease, were included into the study group. There were 81 lesions treated (42 stenosis and 39 occlusions). Percutaneous transluminal angioplasty (PTA) or percutaneous transluminal angioplasty with stenting (PTS) was committed. There was no randomisation. Stent implantation was avoided in vessels with a foreign body inside (catheter or electrode). Diagnostic phlebographies were performed after 12 and 24 months or if symptoms recurred. The follow-up period lasted for 24 months. There were 26 (70%) patients with primary stenosis and 11 (29%) with occlusion in the group with PTA therapy and 13 (38%) and 21 (61%) in the group with PTS therapy. Procedure was successful in all cases of stenosis, unsuccessful in 10 cases of occlusions. Seventeen patients died during first year of observation, 9 during the second. Two patients were lost to follow up. No serious adverse events were observed. Results: Primary patency (PP) after 12 and 24 months was 50% and 26% after PTS, 33% and 21% after PTA respectively. Primary assisted patency (PAP) was 70% and 52% in PTS group while 86% and 92% in PTA group. Secondary patency (SP) 70% and 52% after PTS to 93% and 92% after PTA. Conclusions: Both methods are safe and mildly effective in the treatment of central veins in haemodialysis patients. Both techniques should be applicable in specific clinical settings according to patient status and operator experience

Determination of soil grain size composition by measuring apparent weight of float submerged in suspension

Texture is one of the most significant physical properties of soils. Over the years, several methods of its measuring were developed. The paper presents a method for determining the particle size composition of soils, based on the separation of particles in the sedimentation process. Density of suspension is determined on the basis of apparent weight changes of a float submerged in it. The weight of the float suspended ona thin line, at a given depth in the suspension, is measured with a sensitive piezoelectric dynamometer. The Stokes equation is used to calculate the content of soil fractions with equivalent diameters in the range of 0.001 to 0.1 mm. Digital transmission of results from the dynamometer, the temperature sensor and measurements of the distance defining the depth of immersion of the float to the computer enable calculations of particle size composition to be performed automatically. This paper presents the results of measurements of the particle size composition of artificially generated mixtures of ‘silt’ and ‘clay’. The results are compared with results obtained with other methods (including the laser method). A high level of repeatability of the results and satisfactory compatibility in relation to the reference pipette method are noted