46 research outputs found

    Quantitative modeling of the physiology of ascites in portal hypertension

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    Although the factors involved in cirrhotic ascites have been studied for a century, a number of observations are not understood, including the action of diuretics in the treatment of ascites and the ability of the plasma-ascitic albumin gradient to diagnose portal hypertension. This communication presents an explanation of ascites based solely on pathophysiological alterations within the peritoneal cavity. A quantitative model is described based on experimental vascular and intraperitoneal pressures, lymph flow, and peritoneal space compliance. The model's predictions accurately mimic clinical observations in ascites, including the magnitude and time course of changes observed following paracentesis or diuretic therapy

    Mapping the use of simulation in prehospital care – a literature review

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    The effect of simulated obstructive apnea and hypopnea on aortic diameter and BP.

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    BACKGROUND: Preliminary evidence supports an association between obstructive sleep apnea (OSA) and thoracic aortic dilatation. The mechanisms through which OSA may promote thoracic aortic dilatation are incompletely understood. Therefore, we studied the acute effects of simulated apnea and hypopnea on aortic diameter and BP in humans. METHODS: The diameter of the aortic root was measured in 20 healthy volunteers by echocardiography, and peripheral BP was continuously recorded prior, during, and immediately after simulated obstructive hypopnea (inspiration through threshold load), simulated obstructive apnea (Müller maneuver), end-expiratory central apnea, and normal breathing in randomized order. RESULTS: Proximal aortic diameter increased significantly during inspiration through a threshold load (+6.48%; SE, 3.03; P = .007), but not during Müller maneuver (+3.86%; SE, 2.71; P = .336) or end-expiratory central apnea (+0.62%; SE, 2.94; P = .445). Maneuver-induced changes in mean BP were observed during inspiration through a threshold load (-10.5 mm Hg; SE, 2.2; P < .001), the Müller maneuver (-8.8 mm Hg; SE, 2.4; P < .001), and end-expiratory central apnea (-4.2 mm Hg; SE, 1.4; P = .052). There was a significant increase in mean BP on release of threshold load inspiration (+8.1 mm Hg; SE, 2.9 mm Hg; P = .002), Müller maneuver (+10.7 mm Hg; SE, 2.9; P < .001), and end-expiratory central apnea (+10.6 mm Hg; SE, 2.5; P < .001). CONCLUSIONS: Simulated obstructive hypopnea/apnea and central apnea induced considerable changes in BP, and obstructive hypopnea was associated with an increase in proximal aortic diameter. Further studies are needed to investigate effects of apnea and hypopnea on transmural aortic pressure and aortic diameter to define the role of OSA in the pathogenesis of aortic dilatation

    Mannose-binding lectin protein and its association to clinical outcomes in COPD: a longitudinal study.

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    BACKGROUND: Functional deficiency of mannose-binding lectin (MBL) may contribute to the pathogenesis of chronic obstructive pulmonary disease. We hypothesized that specific MBL2 gene polymorphisms and circulating MBL protein levels are associated with clinically relevant outcomes in the Predicting Outcome using systemic Markers In Severe Exacerbations of COPD PROMISE-COPD cohort. METHODS: We followed 277 patients with stable COPD GOLD stage II-IV COPD over a median period of 733 days (IQR 641-767) taking survival as the primary outcome parameter. Patients were dichotomized as frequent (>/= 2 AECOPD/year) or infrequent exacerbators. Serum MBL levels and single nucleotide polymorphisms of the MBL2 gene were assessed at baseline. RESULTS: The MBL2-HYPD haplotype was significantly more prevalent in frequent exacerbators (OR: 3.33; 95% CI, 1.24-7.14, p = 0.01). The median serum MBL concentration was similar in frequent (607 ng/ml, [IQR; 363.0-896.0 ng/ml]) and infrequent exacerbators (615 ng/ml, [IQR; 371.0-942.0 ng/ml]). Serum MBL was not associated with lung function characteristics or bacterial colonization in sputum. However, high serum MBL at stable state was associated with better survival compared to low MBL (p = 0.046, log rank test). CONCLUSIONS: In COPD, the HYPD haplotype of MBL2 gene is associated with frequent exacerbations and high serum MBL is linked to increased survival. The PROMISE-COPD study was registered at www.controlled-trials.com under the identifier ISRCTN99586989
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