During volume ventilation, peak inspiratory pressure is the ...

[erika]

During volume ventilation, peak inspiratory pressure is the pressure needed to overcome which two of the following factors? 1. Muscle pressure 2. Airflow resistance 3. Elastic recoil pressure 4. Transthoracic pressure
 
  a. 1 and 2 c. 3 and 4
  b. 1 and 3 d. 2 and 3

Question 2

Increased transairway pressure is associated with which two of the following changes? 1. Increased airway resistance 2. Decreased airway resistance 3. Increased static compliance 4. Decreased static compliance
 
  a. 3 and 4 c. 2 and 4
  b. 1 and 3 d. 1 and 2

[verrinzo]

Answer to Question 1

ANS: A
During volume ventilation, pressure increases as the volume is being delivered. The pressure at the end of inspiration, or peak inspiratory pressure, represents the pressure needed to overcome both airflow resistance and the elastic recoil pressure of the lungs and thorax. This concept is demonstrated in the equation of motion: Muscle pressure + Ventilator pressure = Elastic recoil pressure + Flow resistance pressure. Muscle pressure is the pressure generated by a person's mus-cles of ventilation to overcome elastic recoil pressure and airflow resistance. Transthoracic pres-sure is a pressure gradient between the pleural space and the body surface. During spontaneous breathing, it is the total pressure needed to expand or contract the lungs and chest wall together.

Answer to Question 2

ANS: B
Transairway pressure is the pressure required to overcome airflow resistance and is calculated by subtracting the plateau pressure from the peak inspiratory pressure. An increase in the peak in-spiratory pressure with a constant plateau pressure increases the transairway pressure. Another way to increase transairway pressure would be to decrease the plateau pressure (i.e., improved static compliance) and keep a constant peak inspiratory pressure.

[erika]

Excellent

[cici]

Gracias!