When a patient on pressure control experiences an increase in lung secretions, what happens to tidal volume (Vt) and peak inspiratory pressure (PIP)?

In pressure control ventilation, the ventilator delivers a set pressure during inspiration, which means that the clinician defines the maximum pressure limit the machine will reach. When a patient experiences an increase in lung secretions, the airways become more obstructed. As the resistance in the airways increases due to these secretions, the ventilator will work harder to push air into the lungs, leading to changes in tidal volume and peak inspiratory pressure.

When the lung secretions cause increased airway resistance, the tidal volume delivered to the patient typically decreases. This is because the set pressure is not effectively translating into the same volume of air being delivered due to the obstruction caused by secretions. Consequently, with the inadequate volume being delivered, the patient may receive a lower than expected tidal volume.

Simultaneously, as the resistance increases, the pressure needed to achieve the set tidal volume will be higher. However, since the ventilator is set to deliver a specific pressure during pressure control ventilation, it will automatically adjust to maintain that set pressure. If the tidal volume decreases due to resistance, the peak inspiratory pressure may remain stable if the ventilator compensates for or remains within the set limits.

Therefore, in this scenario, the outcome is that tidal volume decreases while