Q: Increased Plateau Pressure (Pplat) on ventilator represents (Select one)

A) static compliance of lung parenchyma
B) static compliance of lung parenchyma and chest wall
C) static compliance of lung parenchyma, chest wall, and abdomen
D) an increase in airway resistance 
E) pressure recorded during a pause at end-expiration


Answer:  C

 The objective of above MCQ is to emphasize the point that increased Plateau Pressure (Pplat) on ventilator represents static compliance of lung parenchyma, chest wall, and abdomen. Effect of abdominal distension on ventilator mechanics is very under-appreciated.

 Choice D is wrong as an increase in resistance of the airways due to various reasons including obstruction of the endotracheal tube is measured by Peak Pressure (Ppeak).

 Choice E is wrong as Plateau Pressure (Pplat) on ventilator represents recorded pressure during a pause at end-inspiration. 


References: 

1.  Tobin MJ. Respiratory monitoring. JAMA 1990; 264:244. 

2. Marini, JJ. Lung mechanics determinations at the bedside: instrumentation and clinical applications. Respir Care 1990; 35:669. 

3. Tobin MJ. Advances in mechanical ventilation. N Engl J Med 2001; 344:1986.