Positive-pressure breaths can be categorized by three variables: the trigger, the limit, and the cycle. They interface the ventilator with the three variables of the breathing pattern: ventilatory drive, ventilatory requirements, and duration and ratio of inspiratory time to total breath cycle duration. The inspiratory effort necessary to trigger a breath is a significant part of the total inspiratory effort; optimization of the triggering mechanisms may improve patient to ventilator interaction. Setting ventilator flow as close as possible to patient's flow by appropriate setting of peak value and waveform profile will also improve patient to ventilator interactions. During pressure support ventilation, ineffective efforts and uncoupling between effort and ventilator output are due to the asynchrony between ventilator and patient's inspiratory time. They may be counterbalanced by adequate peak flow and flow threshold values. Proportional assist ventilation may optimize patient to ventilator interactions, but continuous monitoring of respiratory mechanics should be performed along with its definitive technologic implementation. Its clinical use should be continuously adapted to resistance and elastance measurements.