If you’re looking for a study guide and practice questions about Patient-Ventilator Interactions then you’ve come to the right place. That’s because, as you will see, we’ve listed out this information for you here — designed specifically for Respiratory Therapy Students.

By the way — this study guide correlates well with Egan’s Chapter 47 on Patient-Ventilator Interactions, so you can use it to prepare for your exams.

So if you’re ready to get started, let’s go ahead and dive right in.

Patient-Ventilator Interactions Practice Questions:

1. Why is a patient-ventilator interaction not a problem during controlled ventilation?
Because the patient is not interacting with the ventilator. However, it is always a major issue during patient-triggered ventilation.

2. Poor patient-ventilator interaction has been associated with what?
Increased length of mechanical ventilation, length of ICU stay, need for a tracheotomy, and mortality.

3. A change in patient status is commonly the reason for the development of what?
Poor patient-ventilator interaction.

4. Artificial airway issues can cause what?
Marked changes in patient-ventilator interaction.

5. The development of a pneumothorax or tension pneumothorax is a major cause of what?
Markedly deteriorating patient-ventilator interaction.

6. Whenever there is an acute severe change in the ability to provide ventilatory support the three most probable causes are what?
(1) Tension pneumothorax, (2) Airway obstruction, and (3) Right mainstem bronchus intubation.

7. Why is it unlikely that a malfunction of the mechanical ventilator can be a cause of poor patient-ventilator interaction?
Because with today’s mechanical ventilators, the technology is so advanced that this should never happen.

8. What are the four variables that can be controlled during classic modes of mechanical ventilation?
Pressure, flow, volume, and time.

9. The less control exerted by the mechanical ventilator on the patient’s ventilatory pattern, the less likely it is that the patient will develop what?
Patient-ventilator asynchrony.

10. What are the general types of asynchrony?
Flow asynchrony, trigger asynchrony, cycle asynchrony, and mode asynchrony.

11. Asynchrony can be caused by what?
It can be caused by inappropriately set sensitivity, PEEP, flow, tidal volume, and inspiratory time.

12. Flow asynchrony is a result of what?
The flow provided by the ventilator being inadequate to match the patient’s inspiratory demand.

13. Trigger asynchrony can manifest as what?
Missed triggering, delayed triggering, auto-triggering, double triggering, and reverse triggering.

14. Missed triggering and delayed triggering are normally a result of what?

15. Auto-triggering is normally a result of what?
Circuit leaks or fluid moving back and forth in the ventilator circuit, but can also be caused by hyperdynamic contractions of the myocardium.

16. Flow asynchrony is a result of what?
A result of the ventilator providing less flow then the patient’s respiratory center requires.

17. When does mode asynchrony occur?
When the selected mode of ventilation does not match the patient’s ventilatory demands.

18. Why can volume ventilation be expected to cause the most asynchrony?
Because it controls volume, flow, and time.

19. Which mode of ventilation should result in the least asynchrony?
Pressure Support.

20. Why do PAV and NAVA cause the least asynchrony?
Because they do not force a ventilatory pattern but follow the ventilatory pattern selected by the patient.

21. What causes Trigger Delay?
Auto-PEEP, Poor Sensitivity Setting, and Ventilatory Malfunction.

22. How can a Trigger Delay be modified?
Minimizing Auto-Peep, Apply PEEP, Decrease minute volume/tidal volume, Appropriately set sensitivity, or you may need to replace the ventilator.

23. What causes Auto-triggering?
Circuit leaks, Water in the circuit, Inappropriately set sensitivity, and Hyperdynamic cardiac contractions.

24. How can Auto-triggering be modified?
New ventilator circuit, Removal of water from the circuit, and Appropriate setting of sensitivity.

25. What causes Double Triggering?
Inadequate tidal volume, short inspiratory time, and an inappropriate mode of ventilation.

26. How can Double Triggering be modified?
Increase tidal volume (<8ml/kg PBW), Increase inspiratory time to match patient’s inspiratory time, and Mode changed to pressure support.

27. What is another name for Auto-PEEP?
Missed triggering.

28. What causes missed triggering?
Dynamic airway obstruction and Delivery of excessive minute ventilation/tidal volume.

29. How can Auto-PEEP be modified?
Applied PEEP (only if the patient has difficulty of triggering the ventilator, Decrease airflow obstruction, Secretion management, Aggressive bronchodilation, Larger sized endotracheal tubes, Modify ventilatory pattern, Decrease inspiratory time, Decrease percentage inspiratory time, Decrease Vt, Increase expiratory time (Increase flow) , Decrease rate, and Use a low-compressible volume circuit.

30. What causes Reverse Triggering?
Controlled breath and Expiratory phase.

31. How can Reverse Triggering be modified?
Adjust tidal volume, Adjust the inspiratory time, and Sedation is not the solution.

32. How can Cycle Asynchrony be modified if the Inspiratory time is too short?
If the inspiratory time is too slow, you should Increase the ventilator inspiratory time in pressure A/C or SIMV to eliminate the double trigger at the end of the breath. Decrease the expiratory cycling criteria percentage so that the breath ends sooner, eliminating the double trigger at the end of the breath.

33. How can Cycle Asynchrony be modified if the Inspiratory time is too long?
If it’s too long, you should decrease the ventilator inspiratory time in pressure A/C or SIMV to eliminate the pressure spike at the end of the breath. Increase the expiratory cycling criteria percentage so that the breath ends sooner, eliminating the pressure spike at the end of the breath.

34. What are the four causes of poor patient related interaction with a ventilator?
Abnormal respiratory drive, secretions in the airway, bronchospasm, and abdominal distension.

35. What are some adverse effects of a poor patient-ventilator interaction?
Unstable hemodynamics, ventilatory pattern, and gas exchange values.

36 What can occur to the trachea and mediastinum as a result of a tension pneumothorax?
There will be a shift away from the affected side.

37. What is the primary reason for poor patient-ventilator interaction?
A sudden change in clinical status.

38. What are the first four steps in the management of sudden respiratory distress in a ventilated patient?
(1) Remove the patient from ventilator, (2) Manually ventilate the patient with 100% oxygen, (3) Perform a rapid physical assessment, and (4) Check to be sure for a patent airway.

39. In what mode of ventilation is asynchrony most likely?
Volume Assist-Control.

40. In volume ventilation, what three things can the ventilator control?
Volume, flow and time.

41. In pressure ventilation, what two things can the ventilator control?
Pressure and time.

42. In what mode of ventilation is flow asynchrony most likely?
Volume ventilation.

43. How much flow does a patient with a strong ventilatory demand require?
60 L/min

44. What inspiratory time is usually appropriate to generate flow?
From 0.6 to 0.9 seconds.

45. How can the Respiratory Therapist improve flow asynchrony in pressure ventilation?
Adjust the rise time (0.4 seconds).

46. What is the main contributor to trigger asynchrony?

47. What are some techniques for minimizing the effects of Auto-PEEP?
Decrease the Inspiratory time, bronchodilation, secretion management, and increase the artificial airway size.

48. What are the potential causes for a trigger delay?
Auto-PEEP, ventilator malfunction, and an inappropriate sensitivity setting.

49. What time length should the trigger delay attempt to stay under?
It should stay under 100 milliseconds.

50. Double triggering is most common in what mode of ventilation?
Volume Assist-Control.

51. What are the potential causes of double triggering?
The inspiratory time is too short, and the tidal volume is too low.

52. What are some potential causes of auto-triggering?
Condensation in the tube, or a leak.

53. In what mode of ventilation is cycle asynchrony more common?
Pressure ventilation.

54. What mode of ventilation can be the most problematic because the respiratory center of the brain cannot distinguish between mechanical and spontaneous breaths?

55. How long can it take for a patient to recover from ventilator fatigue?
24 hours.

56. How quick can ventilator atrophy occur?
48 hours.

57. What is a common cause of sudden respiratory distress?
Artificial airways.

58. When more variables are controlled by a ventilator, what can occur?
There is a greater outcome for asynchrony.

59. When does flow asynchrony occur?
It is most common in volume ventilation but can occur in any mode of ventilation.

60. What can be an effect if the rise time is too slow on a patient?
The patient’s work of breathing will increase.

61. In order to prevent flow asynchrony in volume ventilation, the Respiratory Therapist should do what?
Increase the peak flow and decrease the inspiratory time, or change to decelerating flow waveform.

62. In order to prevent flow asynchrony on pressure ventilation, the Respiratory Therapist should do what?
Adjust the rise time.

63. What is the biggest factor in trigger asynchrony?
The presence of Auto-PEEP.

64. How to troubleshoot missed triggering?
Increase the amount of set PEEP, but only if Auto-PEEP is the result.

65. Double triggering can cause what?

66. What is cycle asynchrony?
It occurs when the ventilator ends the breath at a time different from when the patient wants to.

67. What is the most common form of cycle asynchrony?
An inappropriately short Inspiratory time.

68. In what mode of ventilation is asynchrony less likely to occur?

Final Thoughts

So there you have it! That wraps up our study guide on Patient-Ventilator Interactions (from Egan’s Chapter 47). I truly hope that this information was helpful for you.

If you still don’t quite yet get it — that’s okay. Just make sure you set aside some extra time to go through this information again and again until it sticks.

Thank you so much for reading and as always, breathe easy my friend. 


The following are the sources that were used while doing research for this article:

  • Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020. [Link]
  • Chang, David. Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013. [Link]
  • Rrt, Cairo J. PhD. Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 7th ed., Mosby, 2019. [Link]
  • “Patient-Ventilator Asynchrony.” PubMed Central (PMC), 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC6326703.

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