At any given time, 30-70% of patients in the intensive care unit (ICU) are receiving mechanical ventilatory support; 70-80% of them are rapidly weaned off this support, often within a few days.1 Weaning is more problematic in the remaining 20-30% of patients, usually because of unfavourable respiratory mechanics, residual disease processes, cardiac dysfunction, respiratory muscle weakness, high secretion volumes, or altered mental status. The process of weaning from ventilation may account for more than half the total time spent on the ventilator, and it consumes a considerable number of ICU resources.

Failure of weaning increases the length of stay in the ICU and hospital and exposure to the risks of prolonged ventilation, including ventilator associated pneumonia, respiratory muscle deconditioning, and airway problems such as stenosis.2 3 In the linked systematic review and meta-analysis (doi:10.1136/bmj.b1574), Burns and colleagues ask an important question about how to manage patients who fail initial attempts to free them from mechanical ventilation4—is it safer and more effective to wean patients using non-invasive ventilation rather than continuing with invasive support?

In deciding on readiness to wean, reliance on …