Figure 4

Relationship of prior duration of mechanical ventilation and ventilator triggering to diaphragm strength. (A) Transdiaphragmatic twitch pressure (PdiTw) as a function of the duration of mechanical ventilation prior to measurement of PdiTw. There was no statistically significant correlation of PdiTw to duration of ventilation prior to measurement, with a correlation coefficient of 0.020 and P = 0.881 for this assessment (nonsignificant). (B) The majority of subjects actively initiated (that is, triggered) ventilator breaths more than 75% of the time. (C) The level of diaphragm strength (PdiTw) did not correlate with the level of triggering, with the same PdiTw observed at all triggering levels.