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- Borges, Joao Batista, et al.
(författare)
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Lung Inflammation Persists After 27 Hours of Protective Acute Respiratory Distress Syndrome Network Strategy and Is Concentrated in the Nondependent Lung
- 2015
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 43:5, s. E123-E132
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Tidskriftsartikel (refereegranskat)abstract
- Objective: PET with [F-18]fluoro-2-deoxy-D-glucose can be used to image cellular metabolism, which during lung inflammation mainly reflects neutrophil activity, allowing the study of regional lung inflammation in vivo. We aimed at studying the location and evolution of inflammation by PET imaging, relating it to morphology (CT), during the first 27 hours of application of protective-ventilation strategy as suggested by the Acute Respiratory Distress Syndrome Network, in a porcine experimental model of acute respiratory distress syndrome. Design: Prospective laboratory investigation. Setting: University animal research laboratory. Subjects: Ten piglets submitted to an experimental model of acute respiratory distress syndrome. Interventions: Lung injury was induced by lung lavages and 210 minutes of injurious mechanical ventilation using low positive end-expiratory pressure and high inspiratory pressures. During 27 hours of controlled mechanical ventilation according to Acute Respiratory Distress Syndrome Network strategy, the animals were studied with dynamic PET imaging of [F-18]fluoro-2-deoxy-D-glucose at two occasions with 24-hour interval between them. Measurements and Main Results: [F-18]fluoro-2-deoxy-D-glucose uptake rate was computed for the total lung, four horizontal regions from top to bottom (nondependent to dependent regions) and for voxels grouped by similar density using standard Hounsfield units classification. The global lung uptake was elevated at 3 and 27 hours, suggesting persisting inflammation. In both PET acquisitions, nondependent regions presented the highest uptake (p = 0.002 and p = 0.006). Furthermore, from 3 to 27 hours, there was a change in the distribution of regional uptake (p = 0.003), with more pronounced concentration of inflammation in nondependent regions. Additionally, the poorly aerated tissue presented the largest uptake concentration after 27 hours. Conclusions: Protective Acute Respiratory Distress Syndrome Network strategy did not attenuate global pulmonary inflammation during the first 27 hours after severe lung insult. The strategy led to a concentration of inflammatory activity in the upper lung regions and in the poorly aerated lung regions. The present findings suggest that the poorly aerated lung tissue is an important target of the perpetuation of the inflammatory process occurring during ventilation according to the Acute Respiratory Distress Syndrome Network strategy.
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- Santos, Arnoldo, et al.
(författare)
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ARDS Decreases Pulmonary Artery Compliance in a Porcine Model
- 2016
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Ingår i: American Journal of Respiratory and Critical Care Medicine. - 1073-449X .- 1535-4970. ; 93
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Importance of pulmonary hemodynamic disarrangements in ARDS has been remarked recently. In this study we describe the effect of ARDS on pulmonary artery compliance and the related effect on pulmonary hemodynamics. In this way we highlight the importance of pulsatile hemodynamic evaluation beyond the classic evaluation based only on resistance.Methods: 17 anesthetized and muscle relaxed pigs were monitored with a transonic flow probe and high fidelity micro-tip pressure sensor placed in the pulmonary artery through a small thoracotomy. An experimental model of ARDS was induced in these animals by means of lung saline lavages followed by two hours of injurious mechanical ventilation. Pulmonary artery compliance was measured as the stroke volume divided by the pulse pressure. Waveform analysis of pulmonary artery pressure and flow signal was applied to calculate the following variables: first harmonic impedance magnitude (inversely related with arterial compliance), characteristic impedance, wave reflections (which are affected by arterial compliance) magnitude and peak and foot arrival time (normalized to cardiac period). These variables are related to the pulmonary vessels efficiency to transmit pressure and flow produced by the right ventricle. In addition, pulmonary vascular resistance was evaluated as usual. Variables were evaluated before (Baseline) and after (ARDS) development of the model.Results: Comparing with Baseline, ARDS provoked a decrease in pulmonary artery compliance (3.03±0.99 vs 1.53±0.41 ml/mmHg, p<0.001), and in the wave reflections arrival time of foot (0.18±0.09 vs 0.11±0.05, p<0.001) and peak (0.50±0.12 vs 0.39±0.10, p< 0.001) and an increase in the impedance magnitude of the first harmonic (80±29 vs 145±38 dyn.s.cm-5, p<0.001) and in the pulmonary vascular resistance (230±79 vs 504±129 dyn.s.cm-5, p<0.001). Characteristic impedance and wave reflections magnitude showed no differences.Conclusions: In this porcine model, ARDS provoked a decrease in pulmonary artery compliance. This effect was followed by a deterioration of pulmonary vascular efficiency. Our findings can be relevant for the pathophysiology of right ventricle failure during ARDS. This abstract is funded by: European Society of Intensive Care Medicine (ESICM), Basic Science Award 2012, the Swedish Heart and Lung foundation and the Swedish Research Council (K2015-99X-22731-01-4)
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- Spolaor, A., et al.
(författare)
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Diurnal cycle of iodine, bromine, and mercury concentrations in Svalbard surface snow
- 2019
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 19:20, s. 13325-13339
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Tidskriftsartikel (refereegranskat)abstract
- Sunlit snow is highly photochemically active and plays a key role in the exchange of gas phase species between the cryosphere and the atmosphere. Here, we investigate the behaviour of two selected species in surface snow: mercury (Hg) and iodine (I). Hg can deposit year-round and accumulate in the snowpack. However, photo-induced re-emission of gas phase Hg from the surface has been widely reported. Iodine is active in atmospheric new particle formation, especially in the marine boundary layer, and in the destruction of atmospheric ozone. It can also undergo photochemical re-emission. Although previous studies indicate possible post-depositional processes, little is known about the diurnal behaviour of these two species and their interaction in surface snow. The mechanisms are still poorly constrained, and no field experiments have been performed in different seasons to investigate the magnitude of re-emission processes Three sampling campaigns conducted at an hourly resolution for 3 d each were carried out near Ny-Alesund (Svalbard) to study the behaviour of mercury and iodine in surface snow under different sunlight and environmental conditions (24 h darkness, 24 h sunlight and day-night cycles). Our results indicate a different behaviour of mercury and iodine in surface snow during the different campaigns. The day-night experiments demonstrate the existence of a diurnal cycle in surface snow for Hg and iodine, indicating that these species are indeed influenced by the daily solar radiation cycle. Differently, bromine did not show any diurnal cycle. The diurnal cycle also disappeared for Hg and iodine during the 24 h sunlight period and during 24 h darkness experiments supporting the idea of the occurrence (absence) of a continuous recycling or exchange at the snow-air interface. These results demonstrate that this surface snow recycling is seasonally dependent, through sunlight. They also highlight the non-negligible role that snowpack emissions have on ambient air concentrations and potentially on iodine-induced atmospheric nucleation processes.
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