Pulmonary arterial hypertension and sepsis: prothrombotic profile and inflammation can changes pulmonary mechanics?

Pulmonary arterial hypertension (PAH) is associated to cellular and structural alterations of lung vasculature. Endothelial dysfunction promotes vasoconstriction, smooth muscle hypertrophy, intimal proliferation, angioproliferative plexiform lesions, and in situ thrombosis increasing pulmonary vascular resistance and arterial stiffness. Indeed, an inflammatory component has been defined in PAH on the last years. Sepsis is a systemic complex syndrome, of infectious origin. The presence of inflammation is well established in this condition and it is also considered a risk factor for acute lung injury. Thrombotic events play important role in sepsis pathophysiology. The association between PAH and sepsis potentiate the metabolic oxygen consumption/offer imbalance, with very high mortality risk. Furthermore, it is possible that the association of these two conditions should intensify thrombotic events on pulmonary microcirculation, reducing area of pulmonary vascular bed available for blood flow. For the other side, an inflammation synergism observed on these two conditions should increase the respiratory system impedance.

Mechanical evaluation of elastic tubes used in physical therapy.

PURPOSE: To quantify the force of elastic tubes at different elongation patterns used in exercises. METHODS: A tensile test of elastic tubes which had seven levels of resistance identified by colors was performed. All samples (n = 105; 15 samples for each color) were 7 cm of length and had two interfaces for fixation. The samples were tested in a tensile testing hydraulic machine, under elongation control, up to 200% of the original length (21 cm). The force values corresponding to an increase of 50%, 100%, 150% and 200% of the samples initial length were recorded. RESULTS: A strong linear association between force and elongation for all colors was found. There were different forces for each elongation investigated for the same tube and between different tubes in almost all percentage of elongation investigated, except for the red and green tubes (all elongations), and for the blue and black tubes at 50% elongation. CONCLUSION: Mechanical tests revealed different elastic forces for different levels of elongation of each tube. The replication of the results in clinical situations is recommended, so the elastic resistance in clinical routine could be evaluated with more propriety.

Elastic resistance training to increase muscle strength in elderly: a systematic review with meta-analysis.

Analyze the efficiency of training programs with progressive elastic resistance on muscle strength in elderly 'healthy' and 'not healthy'. It was performed a systematic review in relevant databases to identify controlled clinical trials with outcomes from parameters of muscle strength. Two independent reviewers decided about the inclusion criteria, data extraction and evaluation of methodological quality of the articles. Standardized mean difference (SMD) and 95% confidence intervals (CI) were calculated for relevant outcomes and pooled using a random effects model. Among the 11 studies whose effect sizes were used in the meta-analysis, there were 834 individuals between the ages of 60 and 79. The resistance training with elastic bands showed strong effects on muscle strength in healthy elderly (SMD=1.30; 95% CI: 0.90, 1.71) and with some functional incapacity (SMD=1.01; 95% CI: 0.82, 1.19), and a moderate effect on muscle strength in elderly patients with pathology (SMD=0.54; 95% CI: 0.12, 0.96). There was little information available about the training intensity. The training with elastic resistance proved to be effective for improving muscle strength in 'healthy' and 'not healthy' elderly. Our results suggest that training with elastic resistance is most effective in 'healthy' subjects and with functional limitations, and less effective in subjects with some kind of disorders. To establish dose-response relations from different intensities of training on muscle strength in the elderly, new studies are needed to identify reliable and objective methods of evaluation of muscle strength using elastic materials directly.

Influence of lung mechanical properties and alveolar architecture on the pathogenesis of ischemia-reperfusion injury.

We tested the hypothesis that lung preservation techniques disarrange lung architecture, increase pulmonary impedance and lead to ischemia-reperfusion injury, which can be prevented by re-establishment of optimal lung geometry. In the first phase, fresh, cold ischemic, preserved lungs insufflated to total lung capacity (TLC) and preserved lungs ventilated with tidal volume prior to reperfusion were submitted to a 60-min ex-vivo reperfusion to evaluate the gas exchange, pulmonary hemodynamic and lung mechanics' properties. In the second phase, we evaluated the mechanical properties of lungs submitted to the same conditions of the first phase. Cold ischemic lungs developed fulminant edema during the first 15 min of ex-vivo reperfusion, whereas gas exchange, hemodynamic and mechanic properties of lungs insufflated to TLC and ventilated during 10 min prior to reperfusion were similar to fresh lungs. After the pulmonary vascular flush pulmonary impedance and alveolar collapsed area increased significantly. The insufflation to TLC and 10 min of tidal ventilation reduced the lung impedance and the percentage of alveolar collapsed area. Lung preservation techniques disarrange alveolar architecture, which lead to ischemia-reperfusion injury; recruitment maneuvers decrease the pulmonary inhomogeneities and protect the lungs against the ischemia-reperfusion injury.

Análise da mecânica pulmonar em modelo experimental de sepse / Analysis of pulmonary mechanics in an experimental model of sepsis

OBJETIVO: Verificar se há alterações na mecânica pulmonar de camundongos com sepse. MÉTODOS: Foram utilizados 40 camundongos Balb/c divididos em dois grupos: sobrevida (n = 21) e mecânica respiratória (n = 19). O grupo sobrevida foi dividido em três subgrupos: controle (n = 7), subletal (n = 7) e letal (n = 7). O grupo mecânica respiratória também foi dividido em três subgrupos: controle (n = 5), subletal (n = 7) e letal (n = 7). A sepse foi induzida pelo método cecal ligation and puncture, usando-se um estímulo subletal e outro letal. A mecânica pulmonar foi medida oito horas após a intervenção, utilizando-se o método da oclusão ao final da inspiração. Dentro do grupo mecânica pulmonar foram estudadas as seguintes variáveis: variação total de pressão, pressão resistiva, pressão viscoelástica, elastância dinâmica e elastância estática. Os dados foram analisados por meio do teste estatístico ANOVA One-Way. RESULTADOS: Os dados do grupo sobrevida determinaram a eficácia do modelo utilizado. Não houve diferença estatística entre os subgrupos da mecânica pulmonar quando analisadas as elastâncias dinâmica e estática, bem como não houve diferença estatística entre os subgrupos da mecânica pulmonar quando analisadas a variação total de pressão, pressão resistiva e pressão viscoelástica. CONCLUSÃO: Não houve lesão estrutural no pulmão, bem como não houve alteração nos componentes viscoso e viscoelástico do pulmão quando essas variáveis foram estudadas oito horas após a intervenção pelo método cecal ligation and puncture.

OBJECTIVE: To determine whether pulmonary mechanics are altered in mice with sepsis. METHODS: A total of 40 Balb/c mice were divided into two groups: survival (n = 21) and pulmonary mechanics (n = 19). The survival group was divided into three subgroups: control (n = 7), sublethal (n = 7) and lethal (n = 7). The pulmonary mechanics group was also divided into three subgroups: control (n = 5), sublethal (n = 7) and lethal (n = 7). Sepsis was induced through cecal ligation and puncture, the latter varying in degree (sublethal or lethal). At eight hours after the intervention, pulmonary mechanics were measured through end-inflation occlusion. In the pulmonary mechanics group, the following variables were studied: total pressure, resistance, viscoelasticity, dynamic compliance and static compliance. The data obtained were analyzed using one-way ANOVA. RESULTS: The data for the survival group indicate the efficacy of the model employed. There were no statistically significant differences among the pulmonary mechanics subgroups in terms of dynamic compliance, static compliance, total pressure, resistance or viscoelasticity. CONCLUSION: At eight hours after cecal ligation and puncture, there were no changes in the lung parenchyma, nor were any alterations observed in the viscous and viscoelastic components of the lung.

Analysis of pulmonary mechanics in an experimental model of sepsis.

OBJECTIVE: To determine whether pulmonary mechanics are altered in mice with sepsis. METHODS: A total of 40 Balb/c mice were divided into two groups: survival (n = 21) and pulmonary mechanics (n = 19). The survival group was divided into three subgroups: control (n = 7), sublethal (n = 7) and lethal (n = 7). The pulmonary mechanics group was also divided into three subgroups: control (n = 5), sublethal (n = 7) and lethal (n = 7). Sepsis was induced through cecal ligation and puncture, the latter varying in degree (sublethal or lethal). At eight hours after the intervention, pulmonary mechanics were measured through end-inflation occlusion. In the pulmonary mechanics group, the following variables were studied: total pressure, resistance, viscoelasticity, dynamic compliance and static compliance. The data obtained were analyzed using one-way ANOVA. RESULTS: The data for the survival group indicate the efficacy of the model employed. There were no statistically significant differences among the pulmonary mechanics subgroups in terms of dynamic compliance, static compliance, total pressure, resistance or viscoelasticity. CONCLUSION: At eight hours after cecal ligation and puncture, there were no changes in the lung parenchyma, nor were any alterations observed in the viscous and viscoelastic components of the lung.