228 research outputs found
Open the lung with high-frequency oscillation ventilation or conventional mechanical ventilation? It may not matter!
The 'open lung' approach has been proposed as a reasonable ventilation strategy to mitigate ventilator-induced lung injury (VILI) and possibly reduce acute respiratory distress syndrome (ARDS)-related mortality. However, several randomized clinical trials have failed to show any significant clinical benefit of a ventilation strategy applying higher positive end-expiratory pressure (PEEP) and low tidal volume
When pressure does not mean volume? Body mass index may account for the dissociation
Low tidal volume (VT 6 ml/predicted body weight) pressure limited (plateau pressure <30 cmH2O) protective ventilation as proposed by the ARDS Network was associated with an improvement in mortality and is considered the gold standard for acute respiratory distress syndrome (ARDS) ventilation strategies. Limiting plateau pressure minimizes ventilator-induced lung injury by reducing the trans-pulmonary pressure, which is the real alveolar distending pressure. However, in the presence of chest wall elastance impairment, as observed in obese patients, plateau pressure underestimates the trans-pulmonary pressure and derecrutiment at low distending pressure could occur. Moreover, low tidal volume to keep plateau pressure <30 cmH2O could be associated with large differences compared to measured total lung capacity. Quantitative bedside techniques that are able to measure lung volumes together with trans-pulmonary pressure could expand our chances to tailor mechanical ventilation in ARDS patients
Reactive random walkers on complex networks
We introduce and study a metapopulation model of random walkers interacting
at the nodes of a complex network. The model integrates random relocation moves
over the links of the network with local interactions depending on the node
occupation probabilities. The model is highly versatile, as the motion of the
walkers can be fed on topological properties of the nodes, such as their
degree, while any general nonlinear function of the occupation probability of a
node can be considered as local reaction term. In addition to this, the
relative strength of reaction and relocation can be tuned at will, depending on
the specific application being examined. We derive an analytical expression for
the occupation probability of the walkers at equilibrium in the most general
case. We show that it depends on different order derivatives of the local
reaction functions and not only on the degree of a node, but also on the
average degree of its neighbours at various distances. For such a reason,
reactive random walkers are very sensitive to the structure of a network and
are a powerful way to detect network properties such as symmetries or
degree-degree correlations. As possible applications, we first discuss how the
occupation probability of reactive random walkers can be used to define novel
measures of functional centrality for the nodes of a network. We then
illustrate how network components with the same symmetries can be revealed by
tracking the evolution of reactive walkers. Finally, we show that the dynamics
of our model is influenced by the presence of degree-degree correlations, so
that assortative and disassortative networks can be classified by quantitative
indicators based on reactive walkers
Acute respiratory distress syndrome: new definition, current and future therapeutic options.
Since acute respiratory distress syndrome (ARDS) was first described in 1967 there has been large number of studies addressing its pathogenesis and therapies. Despite this intense research activity, there are very few effective therapies for ARDS other than the use of lung protection strategies. This lack of therapeutic modalities is not only related to the complex pathogenesis of this syndrome but also the insensitive and nonspecific diagnostic criteria to diagnose ARDS. This review article will summarize the key features of the new definition of ARDS, and provide a brief overview of innovative therapeutic options that are being assessed in the management of ARDS
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