Efficiency of inertial precipitation of suspended particles in high‐speed fibrous filters

The paper gives theoretic analysis and results of experimental investigation of suspended particle collecting in high‐speed fibrous mist collectors. A dominating role of inertial mechanism of suspended particle precipitation in highspeed mist collectors was determined and a method of calculation of their efficiency by means of probability integral was proposed. Applicability of physical analogy method to deduction of dependency determining values of d50 (diameter of particles collected in an apparatus under given technological mode of its operation with the efficiency of 50 %) on the basis of experimental data is shown. Experimental assembly used for research, testing techniques and result estimating methods are described. Investigation results allowed achieving an improved formula for calculating the value of d50 depending on hydraulic resistance of apparatus and density of collected particles. Suspenduotų dalelių inertinio nusodinimo didelio greičio pluošiniuose filtruose efektyvumas Santrauka Pateikta suspenduotų dalelių surinkimo didelio greičio pluoštiniu aerozolių filtru eksperimentinių tyrimų teorinė analizė ir rezultatai. Apibrėžta dominuojanti suspenduotų dalelių inercijos svarba didelio greičio surinktuvuose ir pasiūlytas skaičiavimo metodas, paremtas filtrų efektyvumo nustatymu integruojant tikimybes. Pateikta galimybė pritaikyti fiziniu aspektu analogišką metodą nustatant priklausomybę, išreiškiančią d50 dalelių (dalelių, kurios surenkamos nurodytu režimu dirbančiame įrenginyje 50 % efektyvumu, skersmuo) vertes remiantis eksperimentiniais duomenimis. Pateiktas tyrimams ir testavimui skirto eksperimentinio agregato aprašymas ir rezultatų skaičiavimo metodai. Tyrimo rezultatai leido patobulinti formulę d50 vertėms apskaičiuoti atsižvelgiant į hidraulinį aparato pasipriešinimą ir surinktų dalelių tankį. Reikšminiai žodžiai: pluoštinis filtras, automatinio modelio veika, inertinio nusodinimo efektyvumas. Эффективность инерционного осаждения взвешенных частиц в высокоскоростных волокнистых фильтрах Резюме Приводится теоретический анализ и результаты экспериментального исследования улавливания взвешенных частиц в высокоскоростных волокнистых туманоуловителях. Установлена доминирующая роль инерционного механизма осаждения взвешенных частиц в высокоскоростных туманоуловителях, и предложен метод расчета их эффективности с помощью интеграла вероятности. Показана возможность использования метода физической аналогии для вывода зависимости, определяющей на основании экспериментальных данных значения величины d50 (диаметр частиц, улавливаемых в аппарате при данном технологическом режиме его работы с эффективностью 50 %). Описана экспериментальная установка, на которой проводились исследования, приведены методики проведения опытов и оценки их результатов. Результаты исследований позволили получить уточненную формулу для расчета величины d50 в зависимости от гидравлического сопротивления аппарата и плотности улавливаемых частиц. Ключевые слова: волокнистый фильтр, автомодельный режим, эффективность инерционного осаждения. First Published Online: 14 Oct 201

Intraoperative transfusion practices in Europe

Transfusion of allogeneic blood influences outcome after surgery. Despite widespread availability of transfusion guidelines, transfusion practices might vary among physicians, departments, hospitals and countries. Our aim was to determine the amount of packed red blood cells (pRBC) and blood products transfused intraoperatively, and to describe factors determining transfusion throughout Europe. We did a prospective observational cohort study enrolling 5803 patients in 126 European centres that received at least one pRBC unit intraoperatively, during a continuous three month period in 2013. The overall intraoperative transfusion rate was 1.8%; 59% of transfusions were at least partially initiated as a result of a physiological transfusion trigger- mostly because of hypotension (55.4%) and/or tachycardia (30.7%). Haemoglobin (Hb)- based transfusion trigger alone initiated only 8.5% of transfusions. The Hb concentration [mean (sd)] just before transfusion was 8.1 (1.7) g dl and increased to 9.8 (1.8) g dl after transfusion. The mean number of intraoperatively transfused pRBC units was 2.5 (2.7) units (median 2). Although European Society of Anaesthesiology transfusion guidelines are moderately implemented in Europe with respect to Hb threshold for transfusion (7-9 g dl), there is still an urgent need for further educational efforts that focus on the number of pRBC units to be transfused at this threshold

Intraoperative transfusion practices in Europe

© 2016 The Author. Published by Oxford University Press on behalf of the British Journal of Anaesthesia.Background: Transfusion of allogeneic blood influences outcome after surgery. Despite widespread availability of transfusion guidelines, transfusion practices might vary among physicians, departments, hospitals and countries. Our aim was to determine the amount of packed red blood cells (pRBC) and blood products transfused intraoperatively, and to describe factors determining transfusion throughout Europe. Methods: We did a prospective observational cohort study enrolling 5803 patients in 126 European centres that received at least one pRBC unit intraoperatively, during a continuous three month period in 2013. Results: The overall intraoperative transfusion rate was 1.8%; 59% of transfusions were at least partially initiated as a result of a physiological transfusion trigger- mostly because of hypotension (55.4%) and/or tachycardia (30.7%). Haemoglobin (Hb)- based transfusion trigger alone initiated only 8.5% of transfusions. The Hb concentration [mean (sd)] just before transfusion was 8.1 (1.7) g dl-1 and increased to 9.8 (1.8) g dl-1 after transfusion. The mean number of intraoperatively transfused pRBC units was 2.5 (2.7) units (median 2). Conclusions: Although European Society of Anaesthesiology transfusion guidelines are moderately implemented in Europe with respect to Hb threshold for transfusion (7-9 g dl-1), there is still an urgent need for further educational efforts that focus on the number of pRBC units to be transfused at this threshold

Intraoperative transfusion practices and perioperative outcome in the European elderly: A secondary analysis of the observational ETPOS study

The demographic development suggests a dramatic growth in the number of elderly patients undergoing surgery in Europe. Most red blood cell transfusions (RBCT) are administered to older people, but little is known about perioperative transfusion practices in this population. In this secondary analysis of the prospective observational multicentre European Transfusion Practice and Outcome Study (ETPOS), we specifically evaluated intraoperative transfusion practices and the related outcomes of 3149 patients aged 65 years and older. Enrolled patients underwent elective surgery in 123 European hospitals, received at least one RBCT intraoperatively and were followed up for 30 days maximum. The mean haemoglobin value at the beginning of surgery was 108 (21) g/l, 84 (15) g/l before transfusion and 101 (16) g/l at the end of surgery. A median of 2 [1–2] units of RBCT were administered. Mostly, more than one transfusion trigger was present, with physiological triggers being preeminent. We revealed a descriptive association between each intraoperatively administered RBCT and mortality and discharge respectively, within the first 10 postoperative days but not thereafter. In our unadjusted model the hazard ratio (HR) for mortality was 1.11 (95% CI: 1.08–1.15) and the HR for discharge was 0.78 (95% CI: 0.74–0.83). After adjustment for several variables, such as age, preoperative haemoglobin and blood loss, the HR for mortality was 1.10 (95% CI: 1.05–1.15) and HR for discharge was 0.82 (95% CI: 0.78–0.87). Preoperative anaemia in European elderly surgical patients is undertreated. Various triggers seem to support the decision for RBCT. A closer monitoring of elderly patients receiving intraoperative RBCT for the first 10 postoperative days might be justifiable. Further research on the causal relationship between RBCT and outcomes and on optimal transfusion strategies in the elderly population is warranted. A thorough analysis of different time periods within the first 30 postoperative days is recommended