(A) Schematic illustration of ineffective effort. Note the small upper deflection in the flow waveform (indicated by the caret) and the small downward deflection in the pressure waveform (indicated by the inverted caret). These are signs of patient effort, which is not followed by a full breath. (B) Schematic illustration of double triggering. Note second breath immediately after the return to expiratory flow from the first breath to zero. (C) Schematic illustration of premature termination. Note the small upward deflection in the expiratory phase of the flow waveform (indicated by the caret) reflecting inspiratory effort by the patient attempt. (D) Schematic illustration of delayed termination. Note the negative flow in the flow waveform while the inspiratory pressure is still maintained (indicated by the caret), reflecting the patient attempt to expire. This precedes full expiratory flow when inspiratory pressure is released.