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

Increased airway resistance due to the patient biting the endotracheal tube In pressure control mode, specific changes in the flow-time scalar can indicate increased airway resistance during inspiration. These include: 1) A sharp spike in flow at the onset of inspiration 2) Loss of the normal exponential decay with a more horizontal or flattened inspiratory flow pattern 3) Failure of the flow to return to baseline by the end of the inspiratory phase. Similarly, signs of incre

In volume control mode, the morphology of the flow-time scalar is fixed and unaffected by respiratory system mechanics or Pmus. However, in pressure control mode, a strong Pmus can alter the morphology of the pressure-time scalar. Instead of the normal exponential decay, a sinusoidal waveform may appear in the presence of strong Pmus, and there may be an increase in the peak inspiratory flow.  The inspiratory limb of the flow-time scalar may reach the baseline early when ther

In pressure control mode, the pressure remains constant regardless of the respiratory mechanics. Conversely, in volume control mode, the morphology of the pressure-time scalar is influenced by Pmus (muscle pressure generated by inspiratory muscles), resistance, and compliance of the respiratory system.  In volume control mode a stronger Pmus can cause a downward deviation in the pressure-time scalar. Increased resistance results in a higher peak inspiratory pressure and a gre

This patient was admitted with CKD, pulmonary edema, and sepsis. Chest examination revealed crackles in both lungs. Tube block was suspected as the waveforms showed increased airway resistance that can be identified by loss of exponential decay in the inspiratory and expiratory flow time scalars and more horizontal course of the flow-time scalar. Waveform changes associated with increased airway resistance: 1) Flow spike at the beginning of inspiration 2) Decreased peak inspi

When there is an auto-PEEP/ air trapping, the expiratory flow-time scalar fails to reach the baseline before the next breath (abrupt termination of expiration).  Auto PEEP occurs when there is an increased airway resistance and/ or inadequate time for exhalation.