While providing pressure-controlled mechanical ventilation with ...

[jazziefee]

While providing pressure-controlled mechanical ventilation with PSV to a patient having respiratory failure caused by airflow obstruction, the therapist notices that the peak flow of the pressure-controlled breath diminishes and that the decelerating flow profile is slow. What action should the therapist take at this time?
 
  A. Increase the rise time.
  B. Decrease the tidal volume.
  C. Increase the flow cycling criterion.
  D. Decrease the inspiratory flow.

Question 2

The flow, volume, and pressure scalars presented here are from a patient who is receiving mechanical ventilatory support for respiratory failure caused by obstructive airway disease. Based on these scalars, which of the following problems is the patient experiencing?
 
  A. triggering dyssynchrony
  B. rapid rise time
  C. auto-PEEP
  D. high Pplateau

[macmac]

Answer to Question 1

ANS: C
A. Incorrect response: See explanation C.
B Incorrect response: See explanation C.
C. Correct response: A specific cycling problem can occur with PSV in patients with airway obstruction. The peak flow of the pressure-controlled breath may be diminished, and the decelerating flow profile may be slow. This situation may cause prolongation of the pressure support breath because the cycling flow value (often 25 to 35 of the peak flow) may take substantial time to reach. Consequently, shortened expiratory times may cause auto-PEEP. Methods of addressing this issue involve increasing the pressure support flow cycling criterion, for example, from 25 to 50 of the peak flow.
D. Incorrect response: See explanation C

Answer to Question 2

ANS: C
A. Incorrect response: See explanation C.
B. Incorrect response: See explanation C.
C. Correct response: The three scalars presented here depict volume controlled mechanical ventilation.


No patient triggering is occurring. During the breaths labeled A and B, the expiratory flow does not return to the baseline before the ensuing inspiration begins. Inspiratory flow is delivered to the patient while expiratory flow from the patient takes place. This situation produces dynamic hyperinflation or auto-PEEP. The Pplateau is 30 cm H2O, which an acceptable pressure level. Keep in mind that in obstructive airway disease, overdistention of healthy lung regions may still occur despite a Pplateau of 30 cm H2O or less.
D. Incorrect response: See explanation C