The therapist is delivering assist-control ventilation providing ...

[armygirl]

The therapist is delivering assist-control ventilation providing a constant VT to a patient experiencing ineffective triggering. The therapist also notes that expiratory flow fails to return to baseline before the initiation of the next mandatory breath. What should the therapist do at this time to correct this problem?
 
  A. Increase the inspiratory flow.
  B. Institute an inspiratory pause.
  C. Conduct an expiratory pause maneuver.
  D. Shorten the expiratory time.

Question 2

As the therapist works with a mechanically ventilated patient, he notices that the ventilator is auto-triggering. What should the therapist do to eliminate this problem? I. Add water to the heated humidifier. II. Check the patient-ventilator system for leaks. III. Scrutinize the breathing circuit for the accumulation of condensate. IV. Ensure that the high-pressure alarm is appropriately set
 
  A. I, II only
  B. II, III only
  C. I, III, IV only
  D, I, II, IV only

[cpetit11]

Answer to Question 1

ANS: A
A. Correct response: This patient is receiving assist-control ventilation with a constant tidal volume and is experiencing ineffective triggering. By increasing the inspiratory flow, the expiratory time lengthens, and the dynamic hyperinflation and auto-PEEP decrease. Otherwise, the patient would be required to develop subatmospheric pressure equivalent to the sum of the applied PEEP and auto-PEEP to trigger inspiration.
B. Incorrect response: Instituting an inspiratory pause would aggravate the problem by lengthening inspiratory time further and shortening expiratory time. This situation would worsen the dynamic hyperinflation.
C. Incorrect response: Performing an expiratory pause maneuver would not rectify this situation.
D. Incorrect response: Shortening the expiratory time would worsen the problem by causing further dynamic hyperinflation.

Answer to Question 2

ANS: B
A. Incorrect response: See explanation B.
B. Correct response: Auto-triggering occurs when the triggering system of the ventilator is overly sensitive. Factors that can cause auto-triggering include condensate in the ventilator breathing circuit and a leak in the patient-ventilator system.
Respiratory system depression associated with a low respiratory rate is susceptible to auto-triggering. This condition prevents flow for a certain period. Zero flow through the system for an extended time makes the system vulnerable to triggering from changes in the airway pressure occurring within the ventilator breathing circuit. These vulnerabilities are not related to patient effort;, rather they pertain to pressure changes within the circuit, even an event as subtle as cardiogenic oscillations.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.