Agreement between direct, oscillometric and Doppler ultrasound blood pressures using three different cuff positions in anesthetized dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Conventional and Doppler ultrasound for the differentiation of benign and malignant canine mammary tumours

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Prevention of experimental venous thrombosis induced by contrast medium in the rat

In order to assess experimentally the usefulness of some procedures employed in man to prevent venous thrombosis following phlebography, thrombosis was induced in rats using sodium diatrizoate in a temporarily isolated segment of a jugular vein. The prevention of thrombosis was attempted by washing out the vein with physiologic saline or saline plus heparin or by injecting saline plus heparin in the opposite jugular vein. Thrombosis occurred in all animals in the control group and in the group treated with saline alone. Both treatment schemes with heparin significantly reduced the incidence of thrombosis, the wash out with heparin being more effective than systemic heparin.

Heparin, heparin plus ASA and dipyridamole, and arteriovenous fistula as adjuvant methods to prevent rethrombosis after venous thrombectomy. Experimental study in rabbits

Venous rethrombosis following thrombectomy is a common event. The aim of the present study was to verify the action of heparin, heparin plus acetyl salicylic acid (ASA) and dipyridamole, and of an arteriovenous fistula (AVF) in the prevention of this complication. Thrombosis was induced in 48 male rabbits by the injection of thrombin in a segment of the left jugular vein, in which the blood flow was arrested for 10 minutes. After 48 hours, the animals were randomly allocated into one of 4 groups of treatment: (1) control, (2) subcutaneous heparin (600 S.I. Units/kg - 8/8 hours), (3) heparin, in the same dose, plus ASA (10 mg/kg/once a day), and dipyridamole (0.5 mg/kg thrice a day), (4) an AVF was surgically constructed between the left carotid after and the left maxillar vein. After 30 minutes, thrombectomy was performed. The venous blood flow, the hematocrit, activated partial thromboplastin time and thrombin time tests were performed before, right after the thrombectomy and 48 hours after thrombectomy. Venography was performed after thrombectomy and at the end of the experiment. The animals were killed 48 hours after thrombectomy and the veins were examined macroscopically. Venous rethrombosis was significantly prevented only in the AVF group (9/12), when compared to control group (0/12), heparin group (1/12) and heparin plus antiaggregating agents group (2/12). These results validate further clinical and experimental investigations with the use of AVF to prevent rethrombosis after venous thrombectomy, when a reduction of venous flow is present.

The first case study of a thunderstorm in South Africa based on dual- Doppler radar observations

On 27 March 1991, an isolated thunderstorm passed between the two CSIR Doppler radars, spaced about 45km apart. Both radars simultaneously recorded Doppler data of the storm, and a detailed case study during an 11-min period is presented. Air motions synthesized from these data provide the first three-dimensional display of Doppler-derived wind fields within a multicell storm on the Transvaal Highveld. Regions of high divergence values (10 -2s -1) at low levels were found mostly in close proximity to reflectivity maxima (45-51 dBZ), which is consistent with findings from North America, that gravitational loading by the precipitation plays a key role in the initiation and maintenance of downdraughts. -from Authors

The frequency of 844ins68 mutation in the cystathionine β-synthase gene is not increased in patients with venous thrombosis

Background and Objectives. A frequent mutation in the cystathionine β- synthase (CBS) gene (844ins68, a 68-bp insertion in the coding region of exon 8) was recently discovered. In the present study we investigated this mutation as a candidate risk factor for venous thrombosis. Design and Methods. The prevalence of the 844ins68 CBS mutation was determined in 101 patients with objectively diagnosed deep venous thrombosis and in 101 healthy controls matched for age, sex and race. PCR amplification of a DNA fragment containing exon 8 of the CBS gene was employed to determine the genotypes. Additionally, Bsrl restriction enzyme digestion of the PCR products was performed in all samples from carriers of the insertion, to test for concurrent presence of a second mutation (T833C) in the CBS gene. Results. The insertion was found in 21 out of 101 patients (20.8%; allele frequency 0.109) and in 20 out of 101 controls (19.8%; allele frequency 0.114), yielding a relative risk for venous thrombosis related to the 844ins68 CBS mutation close to 1.0. In addition, the T833C CBS mutation was detected in all alleles carrying the 844ins68 CBS insertion, confirming the co- inheritance of the two mutations. Interpretation and Conclusions. Our findings do not support the hypothesis that the 844ins68 mutation in the CBS gene is a genetic risk factor for venous thrombosis.

Factor XIII Val34Leu is a genetic factor involved in the aetiology of venous thrombosis

A mutation in the factor XIII gene (FXIII Val34Leu) gene was recently reported to confer protection against myocardial infarction, but its relationship with venous thrombosis is unknown. In addition, a mutation in the 5'-untranslated region of the FXII gene (46 C→T) was identified which is associated with low plasma levels of the protein. Its prevalence in patients with venous thrombosis is also unknown. We investigated the frequency of the FXIII Val34Leu and FXII 46 C→T mutations in 189 patients with deep venous thrombosis and in 187 age-, gender- and race-matched controls. FXIII Val34Leu was detected in 38.6% of the patients and in 41.2% of the controls. Interestingly, homozygosity for the FXIII mutation was found in 1.6% of the patients and in 9.6% of the controls. yielding an odds ratio (OR) for venous thrombosis of 0.16 (95% CI: 0.05-0.5). The OR for heterozygotes was 1.1 (95% CI: 0.7-1.7). The FXII 46 C→T mutation was detected in 46.0% of the patients and in 48.6% of the controls. The OR for heterozygotes was 0.9 (95% CI: 0.6-1.4) and for homozygotes the OR was 0.8 (95% CI: 0.3-1.9). Our data indicate that the FXII 46 C→T mutation is unlikely to be a major risk factor for venous thrombotic disease. In contrast, the homozygous state for FXIII Val34Leu is a strong protective factor against venous thrombosis, which emerges as a novel generic factor involved in the aetiology of thrombophilia.

Abordagem diagnóstica dos pacientes com suspeita de trombose venosa profunda dos membros inferiores

Deep venous thrombosis is a relatively common disease, which can present pulmonary embolism as a complication in its acute phase, and later the post-thrombotic syndrome. Thus, diagnosis should be made as soon as possible, in order to prevent or minimize such complications. Several studies have shown that the symptoms and the clinical signs are inaccurate for the deep venous thrombosis diagnosis and that complementary exams are necessary. As an attempt to simplify the patients' assessment, Well et al., in 1997, developed a clinical prediction index that combines symptoms, signs and risk factors for deep venous thrombosis and managed to make a simpler approach through an association of this index with the complementary exams. Phlebography has been considered the gold standard of complementary exams. However, since it is an invasive exam and thus subject to complications, other diagnostic methods were introduced aiming at making the diagnostic approach simpler and less invasive. Doppler ultrasound, duplex scan, impedance plethysmography, computed tomography, and blood tests such as the D-dimer are some of the available methods for assessing the patient with suspicion of deep venous thrombosis. Among them, duplex scan has shown excellent accuracy and it is currently widely accepted as the first choice test for approaching the patient with deep venous thrombosis. Several authors have suggested an association of diagnostic methods to simplify and make the assessment of such patients more cost-effective, leading to the introduction of a wide range of diagnostic strategies. The different diagnostic methods used for assessing deep venous thrombosis are discussed, as well as a review of the literature on the accuracy, advantages and disadvantages of these methods. Copyright © 2005 by Sociedade Brasileira de Angiologia e Cirurgia Vascular.

Cytokine gene variants and venous thrombotic risk in the BRATROS (BRAZILIAN THROMBOSIS STUDY)

Introduction: Venous thrombosis (VT) and inflammation are two closely related entities. In the present investigation we assessed whether there is a relation between genetic modifiers of the inflammatory response and the risk of VT. Materials and methods: 420 consecutive and unrelated patients with an objective diagnosis of deep VT and 420 matched controls were investigated. The frequencies of the following gene polymorphisms were determined in all subjects: TNF-α- 308 G/A, LT-α+ 252 A/G, IL-6-174 G/C, IL1-ra 86 bp VNTR, IL-10-1082 A/G and CD-31 125 C/G. Results: Overall odds ratio (OR) for VT related to TNF-α- 308 G/A, LT-α+ 252 A/G, IL-6-174 G/C, A1 allele (4 bp repeat) of the IL1-ra 86 bp VNTR, IL-10-1082 A/G and CD-31 125 C/G were respectively: 1.0 (CI95: 0.8-1.5), 1.3 (CI95: 1.0-1.7), 1.1 (CI95: 0.9-1.5), 1.6 (CI95: 1-2.5), 1.2 (CI95: 0.8-1.7) and 0.8 (CI95: 0.6-1.1). A possible interaction between polymorphisms was observed only for the co-inheritance of the mutant alleles of the LT-α+ 252 A/G and IL-10-1082 G/A polymorphisms (OR = 2; CI95: 1.1-3.8). The risk of VT conferred by factor V Leiden and FII G20210A was not substantially altered by co-inheritance with any of the cytokine gene polymorphisms. Conclusions: Cytokine gene polymorphisms here investigated did not significantly influence venous thrombotic risk. © 2006 Elsevier Ltd. All rights reserved.

Risk-assessment algorithm and recommendations for venous thromboembolism prophylaxis in medical patients

The risk for venous thromboembolism (VTE) in medical patients is high, but risk assessment is rarely performed because there is not yet a good method to identify candidates for prophylaxis. Purpose: To perform a systematic review about VTE risk factors (RFs) in hospitalized medical patients and generate recommendations (RECs) for prophylaxis that can be implemented into practice. Data sources: A multidisciplinary group of experts from 12 Brazilian Medical Societies searched MEDLINE, Cochrane, and LILACS. Study selection: Two experts independently classified the evidence for each RF by its scientific quality in a standardized manner. A risk-assessment algorithm was created based on the results of the review. Data synthesis: Several VTE RFs have enough evidence to support RECs for prophylaxis in hospitalized medical patients (eg, increasing age, heart failure, and stroke). Other factors are considered adjuncts of risk (eg, varices, obesity, and infections). According to the algorithm, hospitalized medical patients ≥40 years-old with decreased mobility, and ≥1 RFs should receive chemoprophylaxis with heparin, provided they don't have contraindications. High prophylactic doses of unfractionated heparin or low-molecular-weight-heparin must be administered and maintained for 6-14 days. Conclusions: A multidisciplinary group generated evidence-based RECs and an easy-to-use algorithm to facilitate VTE prophylaxis in medical patients. © 2007 Rocha et al, publisher and licensee Dove Medical Press Ltd.

Echocardiographic Doppler estimation of pulmonary artery pressure in critically ill patients with severe hypoxemia

BACKGROUND: In spontaneously breathing cardiac patients, pulmonary artery pressure (PAP) can be accurately estimated from the transthoracic Doppler study of pulmonary artery and tricuspid regurgitation blood flows. In critically ill patients on mechanical ventilation for acute lung injury, the interposition of gas between the probe and the heart renders the transthoracic approach problematic. This study was aimed at determining whether the transesophageal approach could offer an alternative. METHODS: Fifty-one consecutive sedated and ventilated patients with severe hypoxemia (arterial oxygen tension/fraction of inspired oxygen < 300) were prospectively studied. Mean PAP measured from the pulmonary artery catheter was compared with several indices characterizing pulmonary artery blood flow assessed using transesophageal echocardiography: preejection time, acceleration time, ejection duration, preejection time on ejection duration ratio, and acceleration time on ejection duration ratio. In a subgroup of 20 patients, systolic PAP measured from the pulmonary artery catheter immediately before withdrawal was compared with Doppler study of regurgitation tricuspid flow performed immediately after pulmonary artery catheter withdrawal using either the transthoracic or the transesophageal approach. RESULTS: Weak and clinically irrelevant correlations were found between mean PAP and indices of pulmonary artery flow. A statistically significant and clinically relevant correlation was found between systolic PAP and regurgitation tricuspid flow. In 3 patients (14%), pulmonary artery pressure could not be assessed echocardiographically. CONCLUSIONS: In hypoxemic patients on mechanical ventilation, mean PAP cannot be reliably estimated from indices characterizing pulmonary artery blood flow. Systolic PAP can be estimated from regurgitation tricuspid flow using either transthoracic or transesophageal approach. © 2008 American Society of Anesthesiologists, Inc.