<qa>  What is the main reason for the need for a large randomised controlled trial?Together this highlights the need for a large randomised controlled trial to establish whether VV-ECCO2R in acute hypoxaemic respiratory failure can allow the use of a more protective ventilatory strategy and is associated with improved patient outcomes. Importantly, if there was no benefit, the trial would provide evidence to stop the widespread adoption of an expensive and ineffective or potentially harmful treatment in this setting. 