Flow matters: Avoiding Misinterpretation of Airway Pressure

In volume control mode, an increase in airway resistance results in a rise in peak inspiratory pressure, with a greater difference between the peak and plateau pressures. according to the equation of motion, a similar pattern can also occur when the inspiratory flow is increased, even without changes in resistance. Therefore, when interpreting ventilator waveforms, it is essential to consider the influence of peak inspiratory flow to avoid misattributing changes in pressure to airway pathology. The following example shows two waveforms with different peak inspiratory flow settings, determined by tidal volume and inspiratory time. In the second image, the peak inspiratory flow is higher than the first, resulting in a greater difference between peak and plateau pressures- which could be mistakenly interpreted as an increase in airway resistance.