Early expiratory flow flattening: an alternative sign of delayed cycling in non-invasive ventilation.

A 68-year-old man developed acute hypoxaemic respiratory failure after coronary bypass surgery and was started on non-invasive positive pressure ventilation. He experienced difficulty in exhaling, with expiratory flow flattening noted early in exhalation, despite the absence of the typical late pressure spike of delayed cycling. When the back-up rate was increased, mechanical inspiratory time decreased, the flow flattening disappeared, and his symptoms improved. This case suggests that early expiratory flow flattening may serve as an alternative sign of delayed cycling in non-invasively ventilated patients, reflecting overlap between mechanical insufflation and patient exhalation.