The data on the following ventilator flow sheet for a patient being ventilated in the vol-ume-controlled continuous mandatory ventilation (VC-CMV) mode demonstrates which of the following?

Time PIP (cm H2O) Pplateau (cm H2O) PEEP (cm H2O) Exhaled VT (mL) Flow rate (L/min)
0800 35 30 5 1000 60
1000 39 34 5 1000 60
1100 45 39 5 1000 60
1130 50 44 5 1000 60

a. Airway resistance is increasing.
b. Lung compliance is decreasing.
c. Dynamic compliance is increasing.
d. Water is accumulating in the patient cir-cuit.

ANS: B
This ventilator flow sheet shows that while the peak inspiratory pressure (PIP) and plateau pres-sure (Pplateau) are both increasing over the course of the 3 hours, the transairway pressure (PTA = PIP – Pplateau) has remained almost unchanged (either 5 cm H2O or 6 cm H2O). This means that there has been little change in airway resistance between 0800 and 1130. What is demonstrated is that there is an increase in the Pplateau and that reflects an increase in the elastic resistance of the alveolar walls and thoracic cage against the volume being delivered. This is due to decreasing lung compliance or stiffening of the lungs. The other answers would cause an increase in the PTA.