Figure 3From: Clinical review: Patient-ventilator interaction in chronic obstructive pulmonary diseaseMathematical modeling of the inspiratory instantaneous flow-time curve for progressively increasing levels of airway resistance (Rrs), from normal (5) to severe (20). The cross represents the point at which the inspiratory flow has decreased to 25% of its peak value, and corresponds to the default expiratory trigger (ET) on many ventilators.Back to article page