Previous observational studies have found an association between high inspiratory airway pressures or positive end-expiratory pressure (PEEP) and barotrauma ( 1, 4, 5), whereas others have found no relationship ( 6-8). The determinants of barotrauma in mechanically ventilated patients with acute lung injury or acute respiratory distress syndrome (ALI/ARDS) have not been clearly established ( 1-3). Keywords: acute lung injury adult respiratory distress syndrome mechanical ventilators In conclusion, higher PEEP may increase the likelihood of early barotrauma in ALI/ARDS. Controlling for the covariates, higher PEEP was related to an increased risk of barotrauma (RH 1.50 95% CI 0.98– 2.30). When one-day lagged values of PEEP were analyzed, higher PEEP was associated with a greater risk of barotrauma (RH 1.38 per 5-cm H 2O increment 95% CI 1.09–1.76). In the multivariate analysis, higher concurrent PEEP was also related to a greater risk of barotrauma (RH 1.93 95% CI 1.44–2.60), controlling for age, ventilator group (6 versus 12 ml/kg), baseline PEEP, baseline plateau pressure, baseline tidal volume, Acute Physiology and Chronic Health Evaluation score, vasopressor use, serum albumin, hepatic failure, and coagulopathy. Once concurrent PEEP was selected into the model, no other airway pressure was related to barotrauma, including plateau pressure. In a forward stepwise Cox proportional hazards analysis using time-dependent variables, higher concurrent positive end-expiratory pressure (PEEP) was associated with an increased risk of early barotrauma (relative hazard 1.67 per 5-cm H 2O increment 95% CI 1.35–2.07). During the first four study days, the cumulative incidence of barotrauma was 13% (95% confidence interval 10.6 to 15.6%). We studied airway pressures at three exposure intervals: baseline, one day preceding the barotrauma event (one-day lag), and concurrent with the barotrauma event. Using data from ARDS Network randomized controlled trials, we retrospectively examined the association between airway pressures and the risk of early barotrauma in a cohort of 718 patients with ALI/ARDS and no baseline barotrauma. The researchers found that 90 percent of the dead bats had internal hemorrhaging which matched the symptoms of barotrauma, while only 8 percent had external injuries and no internal bleeding.The determinants of barotrauma in mechanically ventilated patients with acute lung injury or acute respiratory distress syndrome (ALI/ARDS) have not been clearly established. The species of bats found dead on the ground beneath the turbines were primarily three migratory species: hoary bats, eastern red bats, and silver-hair bats. The study, published in the journal Current Biology, was conducted at a windfarm in Alberta, Canada, over the course of two years. īats are particularly susceptible to the condition, called barotrauma, because they have balloon-like, expandable lungs.īird lungs are more rigid and tube-like and better able to withstand sudden changes in air pressure. Their lungs fill with blood and fluid - similar to drowing, the researchers said. When outside pressure drops, the bats' air sac over-expands, bursting the capillaries around it. "It was something nobody could have predicted". "This kind of answers that mystery," she added. "When people were first starting to talk about the issue, it was 'bats running into the turbine blades.' We always said, 'No, bats don't run into things.' Bat's can detect and avoid all kinds of structures." In fact, they are even better at detecting moving objects, Baerwald said. Because bats navigate using a sophisticated echolocation system, researchers thought it was unlikely that the bats were getting caught in the turbines. īut until now, the bats' mode of death was unknown. In May 2007, the US National Research Council published the results of a survey of US wind farms showing that two bat species accounted for 60% of winged animals killed. While environmentalists previously worried about birds getting slashed by the turbines' blades, researchers realized a year ago that bats are more at risk from the the turbines. Wind turbines may be killing bats without touching them: A new study suggests that the localized drop in air pressure caused by the whirling blades is causing the delicate lungs of bats to burst.
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