An increase in airway resistance during pressure-targeted ...

[Deast7027]

An increase in airway resistance during pressure-targeted ventilation will have which of the fol-lowing effects?
 
  a. Volume decrease
  b. Flow increase
  c. Pressure increase
  d. Rate decrease

Question 2

The equation of motion is represented by which of the following?
 
  a. PTA = PA  Raw
  b. PTR = Paw + PA
  c. Pvent + Pmus = Raw + PTA
  d. Pvent + Pmus = Raw  PA

[miss.ashley]

Answer to Question 1

ANS: A
During pressure-targeted (pressure-controlled) ventilation, pressure is unaffected by changes in lung characteristics. However, an increase in airway resistance will cause less volume to be deliv-ered and will change the flow waveform. The set pressure will not be able to overcome the in-creased resistance, resulting in less volume delivery and a decrease in flow (V/TI).

Answer to Question 2

ANS: B
The transrespiratory pressure (PTR) is the pressure generated by either the patient contracting the respiratory muscles or by the ventilator pushing the volume into the patient. This pressure is op-posed by the elastic recoil pressure (PE) and the flow resistance pressure (PR). The transairway pressure (PTA) is the pressure gradient between the airway opening and the alveolus. This pro-duces airway movement in the conductive airways. It represents only part of the equation of mo-tion, the pressure needed to overcome the airway resistance. The equation of motion may be rep-resented, on one side, by Pvent + muscle pressure (Pmus). However, this is equal to the elastic recoil pressure (V/C) plus the flow resistance pressure (Raw  ) or Pvent + Pmus = V/C + (Raw  ).