Increasing airways resistance can be detected when the PIP and plateau pressure behave how?

When there is an increase in airways resistance, it primarily affects the pressure measurements taken during mechanical ventilation. The peak inspiratory pressure (PIP) reflects the total pressure needed to overcome both the resistance and the compliance of the respiratory system. In contrast, plateau pressure is measured during an inspiratory pause and reflects the pressure needed to expand the lung tissues, negating the influence of airway resistance.

As airways resistance increases, the PIP will rise because it takes more pressure to overcome that resistance during inhalation. However, the plateau pressure, which is determined by lung compliance, remains relatively constant if the compliance has not changed. The lungs’ ability to expand does not necessarily change with the airway resistance if the lung tissue itself is still healthy and compliant. This leads to a scenario where PIP increases due to the added resistance while plateau pressure remains constant.

Therefore, when airways resistance increases, you would observe an increase in PIP alongside a constant plateau pressure.