Efeitos do Sildenafil sobre a eficiência ventilatória, mecânica respiratória e dispneia durante o exercício em indivíduos com DPOC leve a moderada

Introdução: Pacientes com doença pulmonar obstrutiva crônica (DPOC) leve apresentam resposta ventilatória exagerada ao exercício, contribuindo para dispneia e intolerância ao exercício. Sabe-se que já nos estágios iniciais da doença (com somente mínimas alterações na espirometria) ocorrem inflamação e disfunção de vias aéreas periféricas, parênquima pulmonar e microvasculatura. Como resultado, anormalidades na troca gasosa e/ou metabólicas, além das alterações na mecânica ventilatória e na função muscular, podem aumentar a demanda ventilatória e contribuir para a dispneia ao esforço. O uso de óxido nítrico inalatório (potente vasodilatador) na DPOC leve durante o exercício produziu um aumento significativo no consumo de oxigênio no pico do exercício, redução na relação ventilação/produção de gás carbônico (V̇E/V̇CO2) e da dispneia. O presente estudo tem como objetivo avaliar os efeitos do sildenafil (em diferentes doses 50 e 100mg) na demanda ventilatória e mecânica respiratória durante o exercício em pacientes com DPOC leve a moderada. Métodos: Estudo randomizado, duplo-cego, no qual foram selecionados pacientes com DPOC leve a moderada e que realizaram, com intervalo mínimo de 48h, dois Testes de Exercício Cardiopulmonar (TECP) incremental 1h após o uso de sildenafil (50 ou 100mg) ou placebo. Nos primeiros 15 pacientes incluídos foi usada dose de 50mg de sildenafil (n=15) após análise preliminar de segurança, foi dobrada a dose (100mg) nos demais 9 pacientes incluídos. Durante o TECP foram avaliadas a demanda ventilatória (V̇E/V̇CO2), a mecânica ventilatória, a eficiência na troca gasosa (gases sanguíneos de sangue arterializado capilar e estimativa da proporção do volume corrente desperdiçada como espaço morto (VD/VT)) e dispneia (escala Borg). Resultados: Incluídos 24 pacientes com DPOC leve a moderada e 11 controles saudáveis. Os pacientes com DPOC apresentaram pior eficiência e mecânica ventilatória, troca gasosa e dispneia durante o exercício em comparação aos controles. A administração de sildenafil (independentemente da dose) não teve efeito sobre V̇E/V̇CO2, VD/VT, mecânica respiratória e dispneia. Os indivíduos que usaram sildenafil apresentaram menor pressão capilar de O2 em repouso (p<0,001), mas essa diferença não se manteve durante o exercício. Conclusão: O uso agudo de sildenafil (independente da dose) não melhorou a demanda ventilatória e a mecânica respiratória durante o exercício em pacientes com DPOC leve a moderada. Consequentemente, não houve melhora na tolerância e percepção de dispneia durante o exercício.Introduction: Patients with mild chronic obstructive pulmonary disease (COPD) have an exaggerated ventilatory response to exercise, contributing to dyspnoea and exercise intolerance. It is known that already in the early stages of the disease (with only minimal changes in spirometry) inflammation and dysfunction of the peripheral airways, lung parenchyma and microvasculature occur. As a result, gas exchange and/or metabolic abnormalities, in addition to changes in ventilatory mechanics and muscle function, can increase ventilatory demand and contribute to dyspnoea on exertion. Use of inhaled nitric oxide (a potent vasodilator) in mild COPD during exercise produced a significant increase in oxygen consumption at peak exercise, a reduction in the ventilation/carbon dioxide production ratio (V̇E/V̇CO2) and dyspnoea. Present study aims to evaluate the effects of sildenafil (at different doses of 50 and 100mg) on ventilatory demand and respiratory mechanics during exercise in patients with mild to moderate COPD. Methods: Randomized, double-blind study, in which patients with mild to moderate COPD were selected and who underwent, with a minimum interval of 48 hours, two incremental Cardiopulmonary Exercise Tests (CPET) 1h after use of sildenafil (50 or 100mg) or placebo. In the first 15 patients included, a dose of 50mg of sildenafil was used (n=15) after a preliminary safety analysis, the dose was doubled (100mg) in the other 9 patients included. During CPET, ventilatory demand (V̇E/V̇CO2), ventilatory mechanics, gas exchange efficiency (blood gases from capillary arterialized blood and estimation of the proportion of tidal volume wasted as dead space (VD/VT)) and dyspnoea (Borg scale). Results: 24 patients with mild to moderate COPD and 11 healthy controls were included. Patients with COPD had worse ventilatory efficiency and mechanics, gas exchange, and dyspnoea during exercise compared to controls. Sildenafil administration (regardless of dose) had no effect on V̇E/V̇CO2, VD/VT, respiratory mechanics and dyspnoea. Individuals who used sildenafil had lower capillary O2 pressure at rest (p<0.001), but this difference was not maintained during exercise. Conclusion: Acute use of sildenafil (dose-independent) did not improve ventilatory demand and respiratory mechanics during exercise in patients with mild to moderate COPD. Consequently, there was no improvement in tolerance and perception of dyspnea during exercise

Investigação dos efeitos de dois níveis de pressão expiratória positiva nas vias aéreas sobre a dispneia, hiperinsuflação pulmonar dinâmica e tolerância ao exercício em portadores de Doença Pulmonar Obstrutiva Crônica

Introdução: A aplicação da pressão positiva expiratória (EPAP) em pacientes com DPOC durante o exercício pode reduzir a hiperinflação dinâmica (HD) e consequentemente a dispneia, enquanto, por outro lado, pode aumentar o trabalho resistivo da respiração. O objetivo do presente estudo foi avaliar os efeitos de duas intensidades de EPAP sobre a capacidade inspiratória, dispneia e tolerância ao exercício em pacientes com DPOC moderada a muito grave. Métodos: Estudo transversal, experimental, de 4 visitas. Na visita 1, os participantes realizaram um teste de exercício cardiopulmonar incremental limitados por sintomas (TECP). Nas visitas 2-4, com pelo menos 48 horas de intervalo, em ordem aleatória, eles realizaram TECP com carga constante (TECPct; 75% da carga de pico) sem EPAP, EPAP com 5cmH2O (EPAP5), ou EPAP com 10cmH2O (EPAP10). Resultados: O estudo incluiu 15 participantes não hipoxêmicos com DPOC moderada a muito grave (média de VEF1= 35,3 ± 10,9% do previsto). As intensidades sucessivas de EPAP durante o TECPct tenderam a causar uma redução progressiva da tolerância ao exercício (p=0,11). Destaca-se que 10 dos 15 pacientes apresentaram menor duração de exercício quando o EPAP10 foi comparado ao teste sem EPAP (-151 ± 105s, p <0,01 ou -41 ± 26%). Além disso, observou-se com EPAP (p <0,05) uma redução significativa da ventilação minuto, as custas de uma restrição na expansão do volume corrente. Por fim, a sensação de dispneia e medidas seriadas da capacidade inspiratória durante o exercício não foram diferentes entre as três intervenções. Conclusão: Níveis progressivos de EPAP durante o exercício tendem a causar uma redução progressiva na tolerância ao exercício em pacientes com DPOC sem melhora na dispneia e HD.Introduction: The application of expiratory positive aiway pressure (EPAP) in COPD patients during exercise may reduce dynamic hyperinflation (DH), and consequently dyspnea, while, on the other hand, can increase the resistive work of breathing. Therefore, the objective of the current study was to evaluate the effects of two intensities of EPAP on inspiratory capacity, dyspnea and exercise tolerance in patients with moderate to very-severe COPD. Methods: Cross-sectional, experimental, 4-visit study. In the Visit 1, participants performed symptom-limited cycling incremental cardiopulmonary exercise test (CPET). In Visits 2-4, at least 48hrs apart, in a randomized order, they performed constant CPET (ctCPET) without EPAP, EPAP with 5cmH2O (EPAP5), or EPAP with 10cmH2O (EPAP10). Results: The study included 15 non-hypoxemic subjects ranging from moderate-to-very-severe COPD (mean FEV1=35.3 ± 10.9% of predicted). Successive intensities of EPAP during ctCPET tended to cause a progressive reduction in exercise tolerance (p=0.11). Of note, 10 of 15 presented shorter exercise duration when EPAP10 was compared to the test without EPAP (-151±105s, p<0.01 or -41±26%). Moreover, significant constraint to minute-ventilation, at expenses of limited tidal volume expansion, was observed with EPAP (p<0.05). Finally, dyspnea sensation and IC measurements were similar during exercise among the interventions. Conclusion: Progressive levels of EPAP during exercise tented to cause a progressive reduction in exercise tolerance in COPD patients without improvement in exercise dyspnea and DH

Effect of the expiratory positive airway pressure on dynamic hyperinflation and exercise capacity in patients with COPD: a meta-analysis

Expiratory positive airway pressure (EPAP) is widely applicable, either as a strategy for pulmonary reexpansion, elimination of pulmonary secretion or to reduce hyperinfation. However, there is no consensus in the literature about the real benefts of EPAP in reducing dynamic hyperinfation (DH) and increasing exercise tolerance in subjects with chronic obstructive pulmonary disease (COPD). To systematically review the efects of EPAP application during the submaximal stress test on DH and exercise capacity in patients with COPD. This meta-analysis was performed from a systematic search in the PubMed, EMBASE, PeDRO, and Cochrane databases, as well as a manual search. Studies that evaluated the efect of positive expiratory pressure on DH, exercise capacity, sensation of dyspnea, respiratory rate, peripheral oxygen saturation, sense of efort in lower limbs, and heart rate were included. GRADE was used to determine the quality of evidence for each outcome. Of the 2,227 localized studies, seven studies were included. The results show that EPAP did not change DH and reduced exercise tolerance in the constant load test. EPAP caused a reduction in respiratory rate after exercise (− 2.33 bpm; 95% CI: − 4.56 to− 0.10) (very low evidence) when using a pressure level of 5 cmH2O. The other outcomes analyzed were not signifcantly altered by the use of EPAP. Our study demonstrates that the use of EPAP does not prevent the onset of DH and may reduce lower limb exercise capacity in patients with COPD. However, larger and higher-quality studies are needed to clarify the potential beneft of EPAP in this population

Supporting elimination of lymphatic filariasis in Samoa by predicting locations of residual infection using machine learning and geostatistics

The global elimination of lymphatic filariasis (LF) is a major focus of the World Health Organization. One key challenge is locating residual infections that can perpetuate the transmission cycle. We show how a targeted sampling strategy using predictions from a geospatial model, combining random forests and geostatistics, can improve the sampling efficiency for identifying locations with high infection prevalence. Predictions were made based on the household locations of infected persons identified from previous surveys, and environmental variables relevant to mosquito density. Results show that targeting sampling using model predictions would have allowed 52% of infections to be identified by sampling just 17.7% of households. The odds ratio for identifying an infected individual in a household at a predicted high risk compared to a predicted low risk location was 10.2 (95% CI 4.2–22.8). This study provides evidence that a ‘one size fits all’ approach is unlikely to yield optimal results when making programmatic decisions based on model predictions. Instead, model assumptions and definitions should be tailored to each situation based on the objective of the surveillance program. When predictions are used in the context of the program objectives, they can result in a dramatic improvement in the efficiency of locating infected individuals

Prevalência de sintomas respiratórios e tabagismo em escolares de Santa Cruz do Sul - RS

Introduction: Smoking is a major public health problem and also responsible for the development of various acute and chronic diseases. Objective: Estimate the prevalence of respiratory symptoms and smoking habits among high school teenagers in Santa Cruz do Sul - RS. Methods: A cross sectional exploratory study with school teenagers who were randomized and responded to questionnaires of respiratory symptoms (Modified from the British Medical Research Council and the European Community Respiratory Health Survey), an investigation smoking and Tolerance Questionnaire of Fagestrom. Results: 350 adolescents from 14 to 21 years with average age of 16.7 ± 5.6 years (56.6% female and 43.4% male) were evaluated. The prevalence of smoking was 10.6% with no difference between sexes (p = 0.880). In smokers adolescents, the respiratory symptoms prevalence was higher than in nonsmokers on issues addressed in the cough (83.8%), sputum (54.1%), wheezing (45.9%) (p = 0.000) and shortness of breath 43.2% (p = 0.001). Conclusion: Considering the age group studied, there was high smoking prevalence as well as increased respiratory symptoms occurrence in adolescents who engage in smoking.Introdução: O tabagismo é um importante problema de saúde pública sendo responsável pelo desenvolvimento de diversas doenças agudas e crônicas. Objetivo: Analisar a prevalência de sintomas respiratórios e hábito tabágico em escolares de Santa Cruz do Sul - RS. Métodos: Trata-se de um estudo transversal que avaliou a prevalência de sintomas respiratórios através do Questionário de Sintomas Respiratórios (Modificado do British Medical Research Council e European Community Respiratory Health Survey) e a prevalência de tabagismo através do Questionário de Tolerância de Fagestrom. Resultados: Foram avaliados 350 adolescentes de 14 a 21 anos com idade média de 16,7 ± 5,6 anos (56,6% feminino e 43,4% masculino). A prevalência de tabagismo na amostra avaliada foi de 10,6% sem ter havido diferença entre os sexos (p = 0,880). Nos adolescentes tabagistas, a prevalência de sintomas respiratórios foi superior aos não tabagistas nas questões abordadas nos sintomas tosse (83,8%), expectoração (54,1%), chiado no peito (45,9%) (p = 0,000) e falta de ar (43,2%) (p = 0,001). Conclusão: Considerando a faixa etária estudada, evidenciou-se alta prevalência de tabagismo bem como maior ocorrência de sintomas respiratórios nos adolescentes que praticam o hábito tabágico