•The oil yield depended on the solvent (hexane>isopropanol>ethanol).•The diffusivity of oil in isopropanol and ethanol were slower than in hexane.•The oil yield increased with the duration of the ...extraction.•Ultrasounds allowed to improve the extraction.•Ultrasounds did not modify the fatty acid composition of oil.
The current procedure of rapeseed oil extraction is based on a first extraction step by pressing followed by a second extraction step with hexane. This solvent being toxic for the users, the consumers and the environment, its use could be forbidden within the coming years. Stimulated by a stringent regulation, the research activity for the replacement of toxic solvents shows a significant development. The aim of this study was to select alternative solvent to hexane such as ethanol or isopropanol, and, to adjust the oil extraction process by developing an ultrasound assisted method. The objective was to reach a comparable efficiency but also to enhance the oil quality. When applied to isopropanol, the ultrasound assisted extraction method has shown promising results, and comparable to those obtained with hexane (oil yield of 80% for hexane and 79% for isopropanol at optimum extraction conditions (20min of ultrasound pretreatment followed by 2h of additional solid/liquid extraction)). Conversely, in studied conditions, ethanol did not seem to be an appropriate alternative solvent to hexane as the extraction yields obtained by using this solvent were quite low.
Background: Pretest probability assessment is necessary to identify patients in whom pulmonary embolism (PE) can be safely ruled out by a negative D‐dimer without further investigations. ...Objective: Review and compare the performance of available clinical prediction rules (CPRs) for PE probability assessment. Patients/methods: We identified studies that evaluated a CPR in patients with suspected PE from Embase, Medline and the Cochrane database. We determined the 95% confidence intervals (CIs) of prevalence of PE in the various clinical probability categories of each CPR. Statistical heterogeneity was tested. Results: We identified 9 CPR and included 29 studies representing 31215 patients. Pooled prevalence of PE for three‐level scores (low, intermediate or high clinical probability) was: low, 6% (95% CI, 4–8), intermediate, 23% (95% CI, 18–28) and high, 49% (95% CI, 43–56) for the Wells score; low, 13% (95% CI, 8–19), intermediate, 35% (95% CI, 31–38) and high, 71% (95% CI, 50–89) for the Geneva score; low, 9% (95% CI, 8–11), intermediate, 26% (95% CI, 24–28) and high, 76% (95% CI, 69–82) for the revised Geneva score. Pooled prevalence for two‐level scores (PE likely or PE unlikely) was 8% (95% CI,6–11) and 34% (95% CI,29–40) for the Wells score, and 6% (95% CI, 3–9) and 23% (95% CI, 11–36) for the Charlotte rule. Conclusion: Available CPR for assessing clinical probability of PE show similar accuracy. Existing scores are, however, not equivalent and the choice among various prediction rules and classification schemes (three‐ versus two‐level) must be guided by local prevalence of PE, type of patients considered (outpatients or inpatients) and type of D‐dimer assay applied.
Background: Multiple‐detectors computed tomographic pulmonary angiography (CTPA) has a higher sensitivity for pulmonary embolism (PE) within the subsegmental pulmonary arteries as compared with ...single‐detector CTPA. Multiple‐detectors CTPA might increase the rate of subsegmental PE diagnosis. The clinical significance of subsegmental PE is unknown. We sought to summarize the proportion of subsegmental PE diagnosed with single‐ and multiple‐detectors CTPA and assess the safety of diagnostic strategies based on single‐ or multiple‐detectors CTPA to exclude PE. Patients and methods: A systematic literature search strategy was conducted using MEDLINE, EMBASE and the Cochrane Register of Controlled Trials. We selected 22 articles (20 prospective cohort studies and two randomized controlled trials) that included patients with suspected PE who underwent a CTPA and reported the rate of subsegmental PE. Two reviewers independently extracted data onto standardized forms. Results: The rate of subsegmental PE diagnosis was 4.7% 95% confidence interval (CI): 2.5–7.6 and 9.4 (95% CI: 5.5–14.2) in patients that underwent a single‐ and multiple‐detectors CTPA, respectively. The 3‐month thromboembolic risks in patients with suspected PE and who were left untreated based on a diagnostic algorithm including a negative CTPA was 0.9% (95% CI: 0.4–1.4) and 1.1% (95% CI: 0.7–1.4) for single‐ and multiple‐detectors CTPA, respectively. Conclusion: Multiple‐detectors CTPA seems to increase the proportion of patients diagnosed with subsegmental PE without lowering the 3‐month risk of thromboembolism suggesting that subsegmental PE may not be clinically relevant.
ABSTRACT
A model that couples stomatal conductance, photosynthesis, leaf energy balance and transport of water through the soil–plant–atmosphere continuum is presented. Stomatal conductance in the ...model depends on light, temperature and intercellular CO2 concentration via photosynthesis and on leaf water potential, which in turn is a function of soil water potential, the rate of water flow through the soil and plant, and on xylem hydraulic resistance. Water transport from soil to roots is simulated through solution of Richards’ equation. The model captures the observed hysteresis in diurnal variations in stomatal conductance, assimilation rate and transpiration for plant canopies. Hysteresis arises because atmospheric demand for water from the leaves typically peaks in mid‐afternoon and because of uneven distribution of soil matric potentials with distance from the roots. Potentials at the root surfaces are lower than in the bulk soil, and once soil water supply starts to limit transpiration, root potentials are substantially less negative in the morning than in the afternoon. This leads to higher stomatal conductances, CO2 assimilation and transpiration in the morning compared to later in the day. Stomatal conductance is sensitive to soil and plant hydraulic properties and to root length density only after approximately 10 d of soil drying, when supply of water by the soil to the roots becomes limiting. High atmospheric demand causes transpiration rates, LE, to decline at a slightly higher soil water content, θs, than at low atmospheric demand, but all curves of LE versus θs fall on the same line when soil water supply limits transpiration. Stomatal conductance cannot be modelled in isolation, but must be fully coupled with models of photosynthesis/respiration and the transport of water from soil, through roots, stems and leaves to the atmosphere.
Twenty years after its first use in the diagnostic workup of suspected venous thromboembolism (VTE), fibrin D‐dimer (DD) testing has gained wide acceptance for ruling out this disease. The test is ...particularly useful in the outpatient population referred to the emergency department because of suspected deep vein thrombosis (DVT) or pulmonary embolism (PE), in which the ruling out capacity concerns every third patient clinically suspected of having the disease. This usefulness is based on the high sensitivity of the test to the presence of VTE, at least for some assays. Due to its poor specificity precluding its use for ruling in VTE, DD testing must be integrated in comprehensive, sequential diagnostic strategies that include clinical probability assessment and imaging techniques such as lower limb venous compression ultrasonography for suspected DVT or multi‐slice helical computed tomography for suspected PE. The present narrative review updates the data available on the use of the various commercially available DD assays in the diagnostic approach of clinically suspected VTE in distinct patient populations or situations, including outpatients and inpatients, patients with cancer, older age, pregnancy, a suspected recurrent event, limited thrombus burden, and patients already on anticoagulant treatment.
Background: Risk factors for post‐thrombotic syndrome (PTS) remain poorly understood.
Objectives: In this multinational multicenter study, we evaluated whether subtherapeutic warfarin ...anticoagulation was associated with the development of PTS.
Methods: Patients with a first unprovoked deep venous thrombosis (DVT) received standard anticoagulation for 5–7 months and were then assessed for PTS. The time in the therapeutic range was calculated from the international normalized ratio (INR) data. An INR below 2, more than 20% of the time, was considered as subtherapeutic anticoagulation.
Results: Of the 349 patients enrolled, 97 (28%) developed PTS. The overall frequency of PTS in patients with subtherapeutic anticoagulation was 33.5%, compared with 21.6% in those with an INR below two for ≤ 20% of the time (P = 0.01). During the first 3 months of therapy, the odds ratio (OR) for developing PTS if a patient had subtherapeutic anticoagulation was 1.78 (95% confidence interval CI 1.10–2.87). After adjusting for confounding variables, the OR was 1.84 (95% CI 1.13–3.01). Corresponding ORs for the full period of anticoagulation were 1.83 (95% CI 1.14–3.00) crude and 1.88 (95% CI 1.15–3.07) adjusted.
Conclusion: Subtherapeutic warfarin anticoagulation after a first unprovoked DVT was significantly associated with the development of PTS.
Essentials
Lower limb ultrasonography (CUS) could be useful in suspected pulmonary embolism (PE).
We performed a metaanalysis on the diagnostic characteristics of CUS in suspected PE.
With a ...sensitivity of 41%, proximal CUS would be positive in one of every 7.3 patients.
Complete CUS has a higher sensitivity but specificity for PE is too low to use it in suspected PE.
Summary
Background
Diagnosis of pulmonary embolism (PE) is commonly based on D‐dimer measurement and computed tomography (CT) angiography. Lower limb vein compression ultrasonography (CUS) for diagnosing deep vein thrombosis may be of interest in patients with suspected PE.
Objectives
We aimed to summarize the data on the diagnostic characteristics of CUS in suspected PE patients.
Patients/Methods
We conducted a literature review by using PUBMED and EMBASE and included 15 prospective studies in which CUS was performed in consecutive patients with suspected PE.
Results
Of the 6991 included patients, 2001 (30%) had pulmonary embolism. Eight of the 15 studies included only outpatients, two included hospitalized patients and five involved both in‐ and outpatients. In 13 studies, only proximal CUS was performed. Two studies analyzed the added value of distal CUS including the calf veins (whole‐leg CUS). Pooled estimate of proximal CUS sensitivity was 41% (95% confidence interval CI, 36–46%) with strong heterogeneity (I square, 79%). Specificity of proximal CUS was 96% (95% CI, 94–98%). The overall positive likelihood ratio for proximal CUS was 11.9 (95% CI, 7.1–19.8), whereas the overall negative likelihood ratio was 0.6 (95% CI, 0.5–0.7). The sensitivity of whole‐leg CUS was 79% (95% CI, 24–98%) and specificity was 84% (95% CI, 76–90%).
Conclusions
Proximal CUS has low sensitivity and cannot be used to rule out PE. Nevertheless, its high specificity allows confirming PE, which may be useful in patients with contraindications to CT angiography. Whole‐leg CUS has a higher sensitivity but low specificity for PE and can therefore not be recommended.
Whether to continue oral anticoagulant therapy beyond 6 months after an "unprovoked" venous thromboembolism is controversial. We sought to determine clinical predictors to identify patients who are ...at low risk of recurrent venous thromboembolism who could safely discontinue oral anticoagulants.
In a multicentre prospective cohort study, 646 participants with a first, unprovoked major venous thromboembolism were enrolled over a 4-year period. Of these, 600 participants completed a mean 18-month follow-up in September 2006. We collected data for 69 potential predictors of recurrent venous thromboembolism while patients were taking oral anticoagulation therapy (5-7 months after initiation). During follow-up after discontinuing oral anticoagulation therapy, all episodes of suspected recurrent venous thromboembolism were independently adjudicated. We performed a multivariable analysis of predictor variables (p < 0.10) with high interobserver reliability to derive a clinical decision rule.
We identified 91 confirmed episodes of recurrent venous thromboembolism during follow-up after discontinuing oral anticoagulation therapy (annual risk 9.3%, 95% CI 7.7%-11.3%). Men had a 13.7% (95% CI 10.8%-17.0%) annual risk. There was no combination of clinical predictors that satisfied our criteria for identifying a low-risk subgroup of men. Fifty-two percent of women had 0 or 1 of the following characteristics: hyperpigmentation, edema or redness of either leg; D-dimer > or = 250 microg/L while taking warfarin; body mass index > or = 30 kg/m(2); or age > or = 65 years. These women had an annual risk of 1.6% (95% CI 0.3%-4.6%). Women who had 2 or more of these findings had an annual risk of 14.1% (95% CI 10.9%-17.3%).
Women with 0 or 1 risk factor may safely discontinue oral anticoagulant therapy after 6 months of therapy following a first unprovoked venous thromboembolism. This criterion does not apply to men.
Diagnostic errors account for more than 8% of adverse events in medicine and up to 30% of malpractice claims. Mechanisms of errors may be related to the working environment but cognitive issues are ...involved in about 75% of the cases, either alone or in association with system failures. The majority of cognitive errors are not related to knowledge deficiency but to flaws in data collection, data integration, and data verification that may lead to premature diagnostic closure. This paper reviews some aspects of the literature on cognitive psychology that help us to understand reasoning processes and knowledge organisation and summarises biases related to clinical reasoning. It reviews the strategies described to prevent cognitive diagnostic errors. Many approaches propose awareness and reflective practice during daily activities, but the improvement of the quality of training at the pre-graduate, postgraduate and continuous levels, by using evidence-based education, should also be considered. Several conditions must be fulfilled to increase the understanding, the prevention, and the correction of diagnostic errors related to clinical reasoning: physicians must be willing to understand their own reasoning and decision processes; training efforts should be provided during the whole continuum of a clinician's career; and the involvement of medical schools, teaching hospitals, and medical societies in medical education research should be increased to improve evidence about error prevention.
Objectives In older patients, the the D-dimer test for pulmonary embolism has reduced specificity and is therefore less useful. In this study a new, age dependent cut-off value for the test was ...devised and its usefulness with older patients assessed.Design Retrospective multicentre cohort study.Setting General and teaching hospitals in Belgium, France, the Netherlands, and Switzerland.Patients 5132 consecutive patients with clinically suspected pulmonary embolism.Intervention Development of a new D-dimer cut-off point in patients aged >50 years in a derivation set (data from two multicentre cohort studies), based on receiver operating characteristics (ROC) curves. This cut-off value was then validated with two independent validation datasets. Main outcome measures The proportion of patients in the validation cohorts with a negative D-dimer test, the proportion in whom pulmonary embolism could be excluded, and the false negative rates.Results The new D-dimer cut-off value was defined as (patient’s age×10) μg/l in patients aged >50. In 1331 patients in the derivation set with an “unlikely” score from clinical probability assessment, pulmonary embolism could be excluded in 42% with the new cut-off value versus 36% with the old cut-off value (<500 μg/l). In the two validation sets, the increase in the proportion of patients with a D-dimer below the new cut-off value compared with the old value was 5% and 6%. This absolute increase was largest among patients aged >70 years, ranging from 13% to 16% in the three datasets. The failure rates (all ages) were 0.2% (95% CI 0% to 1.0%) in the derivation set and 0.6% (0.3% to 1.3%) and 0.3% (0.1% to 1.1%) in the two validation sets.Conclusions The age adjusted D-dimer cut-off point, combined with clinical probability, greatly increased the proportion of older patients in whom pulmonary embolism could be safely excluded.
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