Carbonized blood deposited on fibres during 810, 940 and 1,470 nm endovenous laser ablation: thickness and absorption by optical coherence tomography

Endovenous laser ablation (EVLA) is commonly used to treat saphenous varicosities. Very high temperatures at the laser fibre tip have been reported during EVLA. We hypothesized that the laser irradiation deposits a layer of strongly absorbing carbonized blood of very high temperature on the fibre tip. We sought to prove the existence of these layers and study their properties by optical transmission, optical coherence tomography (OCT) and microscopy. We analysed 23 EVLA fibres, 8 used at 810 nm, 7 at 940 nm and 8 at 1,470 nm. We measured the transmission of these fibres in two wavelength bands (450–950 nm; 950–1,650 nm). We used 1,310 nm OCT to assess the thickness of the layers and the attenuation as a function of depth to determine the absorption coefficient. Microscopy was used to view the tip surface. All fibres showed a slightly increasing transmission with wavelength in the 450–950 nm band, and a virtually wavelength-independent transmission in the 950–1,650 nm band. OCT scans showed a thin layer deposited on all 13 fibres investigated, 6 used at 810 nm, 4 at 940 nm and 3 at 1,470 nm, some with inhomogeneities over the tip area. The average absorption coefficient of the 13 layers was 72 ± 16 mm−1. The average layer thickness estimated from the transmission and absorption measurements was 8.0 ± 2.7 µm. From the OCT data, the average maximal thickness was 26 ± 6 µm. Microscopy of three fibre tips, one for each EVLA wavelength, showed rough, cracked and sometimes seriously damaged tip surfaces. There was no clear correlation between the properties of the layers and the EVLA parameters such as wavelength, except for a positive correlation between layer thickness and total delivered energy. In conclusion, we found strong evidence that all EVLA procedures in blood filled veins deposit a heavily absorbing hot layer of carbonized blood on the fibre tip, with concomitant tip damage. This major EVLA mechanism is unlikely to have much wavelength dependence at similar delivered energies per centimetre of vein. Optical–thermal interaction between the vein wall and the transmitted laser light depends on wavelength

RSI bij studenten: een casestudie naar de omvang, ernst en oorzaken van RSI-gerelateerde klachten

In dit artikel wordt een casestudie beschreven naar de omvang, ernst en mogelijke oorzaken van RSI-gerelateerde klachten bij studenten Industrieel Ontwerpen aan de Technische Universiteit Delft. In 1998 meldden zich een verontrustend aantal studenten met ernstige RSI-klachten bij de faculteit. Sommigen van hen moesten door de ernst van hun klachten de studie zelfs (tijdelijk) onderbreken. Om een duidelijk beeld te krijgen van de RSI-problematiek bij de gehele studentenpopulatie Industrieel Ontwerpen, werd daarom begin 1999 een onderzoeksproject gestart. Door middel van een digitale enquête werden 181 studenten ondervraagd over werkplek, werkwijze, werkorganisatie, werkdruk, lichamelijke conditie, individuele eigenschappen waaronder persoonlijkheidskenmerken en het eventueel optreden van lichamelijke klachten na beeldschermwerk. Een zeer groot percentage (82%) van de respondenten blijkt wel eens lichamelijke klachten na beeldschermwerk te ervaren. Ook de ernst van de klachten blijkt verontrustend; 61% ervaart lichte klachten, 28% ervaart serieuze klachten en 11% ervaart zelfs ernstige klachten (klachten ook 's avonds en gedurende het weekend). De werkplek van de studenten blijkt redelijk goed ingericht. De rapportage van RSI-klachten na beeldschermwerk blijkt echter niet of nauwelijks samen te hangen met de kwaliteit van de werkplek, maar ze blijkt wel duidelijk gerelateerd aan diverse werkdrukfactoren. Veel studenten ervaren de werkdruk ook als hoog. Ze geven aan wel eens te maken te hebben met deadlines en krijgen onvoldoende begeleiding bij taak en/of planningsproblemen etc. Deze studenten blijken significant vaker, maar ook ernstiger klachten te ervaren. Tevens lijken persoonlijkheidsfactoren, het geslacht en de leeftijd/het beginjaar van de studie van invloed te zijn. Zo ervaren vrouwelijke studenten en ouderejaars studenten vaker klachten na beeldschermwerk. De resultaten van dit onderzoek zouden een basis kunnen vormen voor eventuele preventiemaatregelen en/of beleid in de toekomst

Het DISC-model nader onderzocht : resultaten van een Internet-studie in verschillende beroepsgroepen

In this crosssectional internet study, the compensation principle of the Demand-Induced Strain Compensation (DISC)-model was subjected to an empirical verification among 390 employees from various economical sectors. The DISC-model assumes a positive causal relationship between work-related stressors and strains on three qualitatively different domains (cognitive, emotional and physical). According to the compensation principle, these causal relationships are moderated by the availability and use of (matching) work-related resources from the same domain. The results of hierarchical multiple regression analyses did not support the compensation principle. Moreover, a large number of cross-domain correlations were found, especially with regard to emotional resources. The results of this study show that more research on the principles of the DISC-model should is needed. Implications of the use of the internet for research on work stress are discussed

Carbonized blood deposited on fibres during 810, 940 and 1,470 nm endovenous laser ablation: thickness and absorption by optical coherence tomography

Endovenous laser ablation (EVLA) is commonly used to treat saphenous varicosities. Very high temperatures at the laser fibre tip have been reported during EVLA. We hypothesized that the laser irradiation deposits a layer of strongly absorbing carbonized blood of very high temperature on the fibre tip. We sought to prove the existence of these layers and study their properties by optical transmission, optical coherence tomography (OCT) and microscopy. We analysed 23 EVLA fibres, 8 used at 810 nm, 7 at 940 nm and 8 at 1,470 nm. We measured the transmission of these fibres in two wavelength bands (450-950 nm; 950-1,650 nm). We used 1,310 nm OCT to assess the thickness of the layers and the attenuation as a function of depth to determine the absorption coefficient. Microscopy was used to view the tip surface. All fibres showed a slightly increasing transmission with wavelength in the 450-950 nm band, and a virtually wavelength-independent transmission in the 950-1,650 nm band. OCT scans showed a thin layer deposited on all 13 fibres investigated, 6 used at 810 nm, 4 at 940 nm and 3 at 1,470 nm, some with inhomogeneities over the tip area. The average absorption coefficient of the 13 layers was 72 +/- 16 mm(-1). The average layer thickness estimated from the transmission and absorption measurements was 8.0 +/- 2.7 A mu m. From the OCT data, the average maximal thickness was 26 A +/- 6 A mu m. Microscopy of three fibre tips, one for each EVLA wavelength, showed rough, cracked and sometimes seriously damaged tip surfaces. There was no clear correlation between the properties of the layers and the EVLA parameters such as wavelength, except for a positive correlation between layer thickness and total delivered energy. In conclusion, we found strong evidence that all EVLA procedures in blood filled veins deposit a heavily absorbing hot layer of carbonized blood on the fibre tip, with concomitant tip damage. This major EVLA mechanism is unlikely to have much wavelength dependence at similar delivered energies per centimetre of vein. Optical-thermal interaction between the vein wall and the transmitted laser light depends on wavelength

The risk of acute liver injury associated with the use of antibiotics--evaluating robustness of results in the pharmacoepidemiological research on outcomes of therapeutics by a European consortium (PROTECT) project.

PURPOSE: To examine the robustness of findings of case-control studies on the association between acute liver injury (ALI) and antibiotic use in the following different situations: (i) Replication of a protocol in different databases, with different data types, as well as replication in the same database, but performed by a different research team. (ii) Varying algorithms to identify cases, with and without manual case validation. (iii) Different exposure windows for time at risk. METHODS: Five case-control studies in four different databases were performed with a common study protocol as starting point to harmonize study outcome definitions, exposure definitions and statistical analyses. RESULTS: All five studies showed an increased risk of ALI associated with antibiotic use ranging from OR 2.6 (95% CI 1.3-5.4) to 7.7 (95% CI 2.0-29.3). Comparable trends could be observed in the five studies: (i) without manual validation the use of the narrowest definition for ALI showed higher risk estimates, (ii) narrow and broad algorithm definitions followed by manual validation of cases resulted in similar risk estimates, and (iii) the use of a larger window (30 days vs 14 days) to define time at risk led to a decrease in risk estimates. CONCLUSIONS: Reproduction of a study using a predefined protocol in different database settings is feasible, although assumptions had to be made and amendments in the protocol were inevitable. Despite differences, the strength of association was comparable between the studies. In addition, the impact of varying outcome definitions and time windows showed similar trends within the data sources

Validity of diagnostic codes and laboratory measurements to identify patients with idiopathic acute liver injury in a hospital database

PurposeThe development and validation of algorithms to identify cases of idiopathic acute liver injury (ALI) are essential to facilitate epidemiologic studies on drug-induced liver injury. The aim of this study is to determine the ability of diagnostic codes and laboratory measurements to identify idiopathic ALI cases. MethodsIn this cross-sectional validation study, patients were selected from the hospital-based Utrecht Patient Oriented Database between 2008 and 2010. Patients were identified using (I) algorithms based on ICD-9-CM codes indicative of idiopathic ALI combined with sets of liver enzyme values (ALT>2x upper limit of normal (ULN); AST>1ULN+AP>1ULN+bilirubin>1ULN; ALT>3ULN; ALT>3ULN+bilirubin>2ULN; ALT>10ULN) and (II) algorithms based on solely liver enzyme values (ALT>3ULN+bilirubin>2ULN; ALT>10ULN). Hospital medical records were reviewed to confirm final diagnosis. The positive predictive value (PPV) of each algorithm was calculated. ResultsA total of 707 cases of ALI were identified. After medical review 194 (27%) patients had confirmed idiopathic ALI. The PPV for (I) algorithms with an ICD-9-CM code as well as abnormal tests ranged from 32% (13/41) to 48% (43/90) with the highest PPV found with ALT>2ULN. The PPV for (II) algorithms with liver test abnormalities was maximally 26% (150/571). ConclusionsThe algorithm based on ICD-9-CM codes indicative of ALI combined with abnormal liver-related laboratory tests is the most efficient algorithm for identifying idiopathic ALI cases. However, cases were missed using this algorithm, because not all ALI cases had been assigned the relevant diagnostic codes in daily practice. Copyright (c) 2015 John Wiley & Sons, Lt

Validity of diagnostic codes and laboratory measurements to identify patients with idiopathic acute liver injury in a hospital database

Purpose: The development and validation of algorithms to identify cases of idiopathic acute liver injury (ALI) are essential to facilitate epidemiologic studies on drug-induced liver injury. The aim of this study is to determine the ability of diagnostic codes and laboratory measurements to identify idiopathic ALI cases. Methods: In this cross-sectional validation study, patients were selected from the hospital-based Utrecht Patient Oriented Database between 2008 and 2010. Patients were identified using (I) algorithms based on ICD-9-CM codes indicative of idiopathic ALI combined with sets of liver enzyme values (ALT>2× upper limit of normal (ULN); AST>1ULN+AP>1ULN+bilirubin>1ULN; ALT>3ULN; ALT>3ULN+bilirubin>2ULN; ALT>10ULN) and (II) algorithms based on solely liver enzyme values (ALT>3ULN+bilirubin>2ULN; ALT>10ULN). Hospital medical records were reviewed to confirm final diagnosis. The positive predictive value (PPV) of each algorithm was calculated. Results: A total of 707 cases of ALI were identified. After medical review 194 (27%) patients had confirmed idiopathic ALI. The PPV for (I) algorithms with an ICD-9-CM code as well as abnormal tests ranged from 32% (13/41) to 48% (43/90) with the highest PPV found with ALT>2ULN. The PPV for (II) algorithms with liver test abnormalities was maximally 26% (150/571). Conclusions: The algorithm based on ICD-9-CM codes indicative of ALI combined with abnormal liver-related laboratory tests is the most efficient algorithm for identifying idiopathic ALI cases. However, cases were missed using this algorithm, because not all ALI cases had been assigned the relevant diagnostic codes in daily practice

Risks of SARS-CoV-2 transmission between free-ranging animals and captive mink in the Netherlands

In the Netherlands, 69 of the 126 (55%) mink farms in total became infected with SARS-CoV-2 in 2020. Despite strict biosecurity measures and extensive epidemiological investigations, the main transmission route remained unclear. A better understanding of SARS-CoV-2 transmission between mink farms is of relevance for countries where mink farming is still common practice and can be used as a case study to improve future emerging disease preparedness. We assessed whether SARS-CoV-2 spilled over from mink to free-ranging animals, and whether free-ranging animals may have played a role in farm-to-farm transmission in the Netherlands. The study encompassed farm visits, farm questionnaires, expert workshops and SARS-CoV-2 RNA and antibody testing of samples from target animal species (bats, birds and free-ranging carnivores). In this study, we show that the open housing system of mink allowed access to birds, bats and most free-ranging carnivores, and that direct and indirect contact with mink was likely after entry, especially for free-ranging carnivores and birds. This allowed SARS-CoV-2 exposure to animals entering the mink farm, and subsequent infection or mechanical carriage by the target animal species. Moreover, mink can escape farms in some cases, and two SARS-CoV-2-positive mink were found outside farm premises. No other SARS-CoV-2-RNA-positive free-ranging animals were detected, suggesting there was no abundant circulation in the species tested during the study period. To investigate previous SARS-CoV-2 infections, SARS-CoV-2 antibody detection using lung extracts of carcasses was set up and validated. One tested beech marten did have SARS-CoV-2 antibodies, but the closest SARS-CoV-2-infected mink farm was outside of its home range, making infection at a mink farm unlikely. Knowing that virus exchange between different species and the formation of animal reservoirs affects SARS-CoV-2 evolution, continued vigilance and monitoring of mink farms and surrounding wildlife remains vital