Maximal respiratory static pressures in patients with different stages of COPD severity

<p>Abstract</p> <p>Background</p> <p>In this study, we analyzed maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) values in a stable COPD population compared with normal subjects. We evaluated the possible correlation between functional maximal respiratory static pressures and functional and anthropometric parameters at different stages of COPD. Furthermore, we considered the possible correlation between airway obstruction and MIP and MEP values.</p> <p>Subject and methods</p> <p>110 patients with stable COPD and 21 age-matched healthy subjects were enrolled in this study. Patients were subdivided according to GOLD guidelines: 31 mild, 39 moderate and 28 severe.</p> <p>Results</p> <p>Both MIP and MEP were lower in patients with severe airway impairment than in normal subjects. Moreover, we found a correlation between respiratory muscle function and some functional and anthropometric parameters: FEV₁(forced expiratory volume in one second), FVC (forced vital capacity), PEF (peak expiratory flow), TLC (total lung capacity) and height. MIP and MEP values were lower in patients with severe impairment than in patients with a slight reduction of FEV₁.</p> <p>Conclusion</p> <p>The measurement of MIP and MEP indicates the state of respiratory muscles, thus providing clinicians with a further and helpful tool in monitoring the evolution of COPD.</p

A method to study the effect of bronchodilators on smoke retention in COPD patients: study protocol for a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Chronic obstructive pulmonary disease (COPD) is a common disease, associated with cardiovascular disease. Many patients use (long-acting) bronchodilators, whilst they continue smoking alongside. We hypothesised an interaction between bronchodilators and smoking that enhances smoke exposure, and hence cardiovascular disease. In this paper, we report our study protocol that explores the fundamental interaction, i.e. smoke retention.</p> <p>Method</p> <p>The design consists of a double-blinded, placebo-controlled, randomised crossover trial, in which 40 COPD patients smoke cigarettes during both undilated and maximal bronchodilated conditions. Our primary outcome is the retention of cigarette smoke, expressed as tar and nicotine weight. The inhaled tar weights are calculated from the correlated extracted nicotine weights in cigarette filters, whereas the exhaled weights are collected on Cambridge filters. We established the inhaled weight calculations by a pilot study, that included paired measurements from several smoking regimes. Our study protocol is approved by the local accredited medical review ethics committee.</p> <p>Discussion</p> <p>Our study is currently in progress. The pilot study revealed valid equations for inhaled tar and nicotine, with an R²of 0.82 and 0.74 (p < 0.01), respectively. We developed a method to study pulmonary smoke retentions in COPD patients under the influence of bronchodilation which may affect smoking-related disease. This trial will provide fundamental knowledge about the (cardiovascular) safety of bronchodilators in patients with COPD who persist in their habit of cigarette smoking.</p> <p>Trial registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00981851">NCT00981851</a></p

Epidemiology, radiology, and genetics of nicotine dependence in COPD

<p>Abstract</p> <p>Background</p> <p>Cigarette smoking is the principal environmental risk factor for developing COPD, and nicotine dependence strongly influences smoking behavior. This study was performed to elucidate the relationship between nicotine dependence, genetic susceptibility to nicotine dependence, and volumetric CT findings in smokers.</p> <p>Methods</p> <p>Current smokers with COPD (GOLD stage ≥ 2) or normal spirometry were analyzed from the COPDGene Study, a prospective observational study. Nicotine dependence was determined by the Fagerstrom test for nicotine dependence (FTND). Volumetric CT acquisitions measuring the percent of emphysema on inspiratory CT (% of lung <-950 HU) and gas trapping on expiratory CT (% of lung <-856 HU) were obtained. Genotypes for two SNPs in the CHRNA3/5 region (rs8034191, rs1051730) previously associated with nicotine dependence and COPD were analyzed for association to COPD and nicotine dependence phenotypes.</p> <p>Results</p> <p>Among 842 currently smoking subjects (335 COPD cases and 507 controls), 329 subjects (39.1%) showed high nicotine dependence. Subjects with high nicotine dependence had greater cumulative and current amounts of smoking. However, emphysema severity was negatively correlated with the FTND score in controls (ρ = -0.19, p < .0001) as well as in COPD cases (ρ = -0.18, p = 0.0008). Lower FTND score, male gender, lower body mass index, and lower FEV1 were independent risk factors for emphysema severity in COPD cases. Both CHRNA3/5 SNPs were associated with FTND in current smokers. An association of genetic variants in CHRNA3/5 with severity of emphysema was only found in former smokers, but not in current smokers.</p> <p>Conclusions</p> <p>Nicotine dependence was a negative predictor for emphysema on CT in COPD and control smokers. Increased inflammation in more highly addicted current smokers could influence the CT lung density distribution, which may influence genetic association studies of emphysema phenotypes.</p> <p>Trial registration</p> <p>ClinicalTrials (NCT): <a href="http://www.clinicaltrials.gov/ct2/show/NCT00608764">NCT00608764</a></p

Dynamic Analysis of a Disequilibrium Macroeconomic Model with Dual Labor Markets

We extend the general disequilibrium model of Malinvaud(1980) by using dual labor market theory. By considering two tiers of workers, we find that while the duality of the labor market expands an equilibrium regime in the short term, it does not always keep an equilibrium in the medium term. In the medium term, the business cycle converges toward a disequilibrium regime unless the goods market is potentially in equilibrium. Employment and wages at the steady state are affected by the size of the government, and the stability of wage bargaining is only a sufficient condition of the local stability of our dynamic system. Therefore, involuntary unemployment can be remedied only when goods demand is sufficiently large

Coordinated Tax-Tariff Reforms, Informality, and Welfare Distribution

The paper studies the revenue, efficiency, and distributional implications of a simple strategy of offsetting tariff reductions with increases in destination-based consumption taxes so as to leave consumer prices unchanged. We employ a dynamic micro-founded macroeconomic model of a small open developing economy, which features an informal sector that cannot be taxed, a formal agricultural sector, and an import-substitution sector. The reform strategy increases government revenue, imports, exports, and the informal sector. In contrast to Emran and Stiglitz (2005), who ignore the dynamic effects of taxes and tariffs on factor markets, we find an efficiency gain, which is unevenly distributed. Existing generations benefit more than future generations, who (depending on pre-existing tax and tariff rates and the informal sector size) even may become worse off