Experimental: Pleural drainage

Ultrasonography-guided pleural drainage with insertion of a small-bore intrapleural catheter (typically pig-tail type catheter, size 6-14 French), conducted by e.g., intensivists or radiologists, as by local standards, of the pleural cavity with the estimated largest pleural effusion as soon as possible. A time interval of up to 24 hours from randomisation to intervention is expected. If bilateral pleural effusions ≥ 2 cm are present at randomisation, drainage of contralateral pleura should be conducted as soon as possible according to local standards, at least within 24 hours from insertion of the first pleural catheter unless pleural effusion has receded to \< 2 cm prior to drainage. Inserted pleural catheters remain connected to a closed pleural drainage system, in situ and open until removed at clinicians' discretion according to local standards. New pleural effusion ≥ 2 cm during ICU stay within 90 days from randomisation will be drained similarly.

No_intervention: No pleural drainage

No pleural drainage is conducted during ICU stay in 90 days from randomisation, unless escape protocol criteria are present being suspected or confirmed haemothorax, suspected or confirmed pneumothorax, suspected or confirmed pleural empyema, suspected or confirmed pleural malignancy, or indication for therapeutic pleural drainage as per the treating clinician and invasive or non-invasive mechanical ventilation or mask CPAP with arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) ratio ≤ 13.3 kPa in the most recent ABG analysis, high-flow humidified oxygen therapy with a flow ≥ 50 L/min and a PaO2/FiO2 ratio ≤ 13.3 kPa in the most recent ABG analysis, or persistent respiratory acidosis with a pH \< 7.25 and an arterial partial pressure of carbon dioxide (PaCO2) \> 6.0 kPa on the most recent ABG analysis in spite of non-invasive ventilation for \> 1 hour.