Abstract
BackgroundPleural effusion is common during invasive mechanical ventilation, but its role during weaning is unclear. We aimed at assessing the prevalence and risk factors for pleural effusion at initiation of weaning. We also assessed its impact on weaning outcomes and its evolution in patients with difficult weaning.MethodsWe performed a prospective multicenter study in five intensive care units in France. Two hundred and forty-nine patients were explored using ultrasonography. Presence of moderate-to-large pleural effusion (defined as a maximal interpleural distance ≥ 15 mm) was assessed at weaning start and during difficult weaning.ResultsSeventy-three (29%) patients failed weaning, including 46 (18%) who failed the first spontaneous breathing trial (SBT) and 39 (16%) who failed extubation. Moderate-to-large pleural effusion was detected in 81 (33%) patients at weaning start. Moderate-to-large pleural effusion was associated with more failures of the first SBT [27 (33%) vs. 19 (11%), p < 0.001], more weaning failures [37 (47%) vs. 36 (22%), p < 0.001], less ventilator-free days at day 28 [21 (5–24) vs. 23 (16–26), p = 0.01], and a higher mortality at day 28 [14 (17%) vs. 14 (8%), p = 0.04]. The association of pleural effusion with weaning failure persisted in multivariable analysis and sensitivity analyses. Short-term (48 h) fluid balance change was not associated with the evolution of interpleural distance in patients with difficult weaning.ConclusionsIn this multicenter observational study, pleural effusion was frequent during the weaning process and was associated with worse weaning outcomes.
Highlights
Several factors may contribute to the occurrence of pleural effusions in critically ill patients, including heart failure, pneumonia, hypoalbuminemia, and fluid overload [1]
Because some patients could not be classified with this definition, weaning was categorized according to the WIND definition [13] as follows: short when the first spontaneous breathing trial (SBT) resulted in a successful termination of the weaning process or death within 1 day after the first SBT; difficult in case of successful weaning or death after more than 1 day but in less than 1 week after the first SBT; prolonged if weaning was still not terminated 7 days after the first SBT
Ventilator-free days at day 28 were computed as days without invasive mechanical ventilation during the 28 days following first SBT; patients who died before day 28 or were dependent on mechanical ventilation for more than 28 days after the first SBT had zero ventilator-free days [14]
Summary
Several factors may contribute to the occurrence of pleural effusions in critically ill patients, including heart failure, pneumonia, hypoalbuminemia, and fluid overload [1]. Pleural effusion was found in 83% of patients with acute respiratory distress. The presence of pleural effusion is associated with a longer duration of mechanical ventilation and intensive care unit (ICU) stay [2]. The capacity of the diaphragm to generate pressure decreases when pleural effusion increases [5, 6]. Drainage of large pleural effusions improves oxygenation and respiratory mechanics in mechanically ventilated patients [4, 7]. Pleural effusion is common during invasive mechanical ventilation, but its role during weaning is unclear. We aimed at assessing the prevalence and risk factors for pleural effusion at initiation of weaning. We assessed its impact on weaning outcomes and its evolution in patients with difficult weaning
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