The following example shows a sequence of images in a pressure support mode. In the first image, the pressure-time scalar shows a progressive increase in the inspiratory pressure drop during the trigger phase, indicating increasing patient inspiratory effort. Correspondingly, there is an increase in both peak inspiratory flow and tidal volume. Over the next few breaths, a gradual reduction in inspiratory effort is observed, reflected by decreasing peak inspiratory flow and ti

In cases where a patient exerts minimal inspiratory effort, the flow-time scalar usually displays an exponential decay, while the pressure remains constant throughout the inspiratory phase in pressure support mode. A similar appearance can also be observed during false triggering when the patient is in a passive state.  In the second breath, the waveform exhibits typical characteristics of pressure support waveforms, indicating the possibility of either a patient-triggered br

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 t

In pressure control mode, increased airway resistance alters the inspiratory flow waveform in the following ways: Reduced peak inspiratory flow Flattening of normal exponential decay, resulting in a decreased slope Flow may fail to return to baseline before expiration, reflecting long time constant Similar abnormalities can also be seen in the expiratory flow-time curve (loss of normal exponential decay). Additionally, air trapping/ auto PEEP can be noticed at the end of expi

In pressure support mode, the cycling mechanism is known as flow cycling. In this mode, the operator sets the percentage of peak inspiratory flow as a cycling criteria. The ventilator terminates the inspiratory phase when the inspiratory flow drops to the predetermined percentage of the peak inspiratory flow. Note: Ventilator settings, patients' inspiratory effort, and respiratory mechanics impact the peak inspiratory flow E.g. 1: End inspiration setting (Expiratory trigger s

In pressure support mode, the ventilator terminates inspiration when the flow decreases to a predetermined percentage of the peak inspiratory flow (end inspiration/ expiratory trigger sensitivity). For instance, if the peak inspiratory flow is 60 litres per minute and the cycling setting is 25%, the ventilator concludes the inspiratory phase when the flow reaches 15 litres per minute. Some ventilators come with a default cycling setting of 25%. Adjusting the cycling setting t