1. A method for improving an accuracy of estimating an exhalation volume while ventilating a patient with a ventilator, the ventilator comprising at least one processor and at least one memory, the method comprising: determining, by the ventilator, an initial base flow to improve the accuracy of estimating the exhalation volume; determining, by the ventilator, an initial inspiration trigger threshold to prevent false triggering while base flow is changing; delivering the initial base flow during at least a first portion of exhalation while setting the inspiration trigger threshold to the initial inspiration trigger threshold; determining, by the ventilator, a desired base flow; determining, by the ventilator, a desired inspiration trigger threshold; increasing base flow from the initial base flow toward the desired base flow during at least a second portion of exhalation; decreasing the inspiration trigger threshold from the initial inspiration trigger threshold toward the desired inspiration trigger threshold while performing the step of increasing the base flow; and increasing a sensitivity to a patient initiated trigger during at least the second portion of exhalation while performing the steps of increasing the base flow and decreasing the inspiration trigger threshold.