RRT RRT Mechanical Ventilation 2 — Questions and Answers
Question 1: During a spontaneous breathing trial (SBT), which finding suggests the patient is NOT ready for extubation?
- Respiratory rate of 18 breaths/min
- SpO2 of 96% on 40% FiO2
- Rapid shallow breathing index (RSBI) of 120 (Correct answer)
- Stable heart rate and blood pressure
Correct answer: Rapid shallow breathing index (RSBI) of 120
An RSBI (f/VT) above 105 indicates a high likelihood of extubation failure due to inefficient, rapid, and shallow breathing.
Question 2: What is the primary purpose of adding pressure support in SIMV mode?
- To guarantee a backup rate
- To overcome the work of breathing imposed by the endotracheal tube and circuit (Correct answer)
- To set a maximum tidal volume
- To trigger mandatory breaths
Correct answer: To overcome the work of breathing imposed by the endotracheal tube and circuit
Pressure support in SIMV reduces the inspiratory work of breathing through the high-resistance ETT during spontaneous breaths.
Question 3: Which parameter is used to calculate the driving pressure in mechanical ventilation?
- Peak pressure minus PEEP
- Plateau pressure minus PEEP (Correct answer)
- Mean airway pressure minus PEEP
- Peak pressure minus plateau pressure
Correct answer: Plateau pressure minus PEEP
Driving pressure = plateau pressure − PEEP, reflecting the tidal stress placed on the respiratory system with each breath.
Question 4: In pressure-controlled ventilation, what happens to tidal volume if lung compliance decreases?
- Tidal volume increases
- Tidal volume stays the same
- Tidal volume decreases (Correct answer)
- Respiratory rate automatically increases
Correct answer: Tidal volume decreases
In pressure-controlled mode, the driving pressure is fixed; decreased compliance results in smaller tidal volumes delivered per breath.
Question 5: What is the best initial ventilator setting for FiO2 when initiating mechanical ventilation?
- 0.21 (room air)
- 0.40
- 1.0 (100%), then titrate down (Correct answer)
- 0.60
Correct answer: 1.0 (100%), then titrate down
Starting at FiO2 1.0 ensures adequate oxygenation during the initial unstable period; it is then titrated to the lowest level maintaining SpO2 ≥92%.
Question 6: High-frequency oscillatory ventilation (HFOV) is characterized by which of the following?
- Large tidal volumes at low frequency
- Very small tidal volumes at high frequency (3–15 Hz) (Correct answer)
- Normal tidal volumes with high PEEP
- Intermittent sighing breaths at set intervals
Correct answer: Very small tidal volumes at high frequency (3–15 Hz)
HFOV uses tidal volumes smaller than anatomical dead space delivered at 3–15 Hz, relying on non-convective gas transport mechanisms.
RRT RRT Mechanical Ventilation 2
During a spontaneous breathing trial (SBT), which finding suggests the patient is NOT ready for extubation?