FFICM Respiratory Management and Mechanical Ventilation 2 — Questions and Answers
Question 1: Which combination of criteria most appropriately indicates readiness to perform a spontaneous breathing trial (SBT)?
- FiO2 ≤0.4, PEEP ≤5–8 cmH2O, hemodynamic stability without high-dose vasopressors (Correct answer)
- FiO2 >0.6 with improving chest radiograph and stable neurology
- PEEP >10 cmH2O with resolving bilateral infiltrates
- Two or fewer vasopressors regardless of FiO2 requirements
Correct answer: FiO2 ≤0.4, PEEP ≤5–8 cmH2O, hemodynamic stability without high-dose vasopressors
SBT readiness requires adequate oxygenation on low FiO2/PEEP, hemodynamic stability, and the ability to initiate spontaneous breaths.
Question 2: What is the dominant mechanism by which ventilator-associated pneumonia (VAP) develops in ICU patients?
- Microaspiration of colonised oropharyngeal secretions past the endotracheal tube cuff (Correct answer)
- Haematogenous seeding from a distant infection source
- Retrograde contamination from the ventilator circuit
- Reactivation of latent pulmonary organisms due to immunosuppression
Correct answer: Microaspiration of colonised oropharyngeal secretions past the endotracheal tube cuff
VAP most commonly results from microaspiration of bacteria-laden oropharyngeal secretions that pool above the cuff and leak into the lower airways.
Question 3: A Rapid Shallow Breathing Index (RSBI) greater than 105 breaths/min/L during an SBT predicts:
- High likelihood of spontaneous breathing trial failure (Correct answer)
- Successful extubation readiness
- Need to increase PEEP before extubation
- Requirement for neuromuscular blockade
Correct answer: High likelihood of spontaneous breathing trial failure
An RSBI >105 indicates rapid, shallow breathing consistent with respiratory muscle fatigue, predicting SBT failure with high sensitivity.
Question 4: Ventilator-Induced Diaphragm Dysfunction (VIDD) is best described as:
- Diaphragmatic atrophy and contractile weakness caused by controlled mechanical ventilation (Correct answer)
- Phrenic nerve injury from prolonged endotracheal tube placement
- Diaphragm rupture secondary to excessive tidal volume delivery
- Paradoxical diaphragm motion caused by high PEEP
Correct answer: Diaphragmatic atrophy and contractile weakness caused by controlled mechanical ventilation
VIDD develops rapidly (within hours) when controlled ventilation eliminates diaphragm contractions, leading to disuse atrophy and oxidative injury.
Question 5: Which single intervention has the strongest evidence for reducing ventilator-associated events (VAE) in ICU patients?
- Maintaining the head of bed at 30–45 degrees to reduce aspiration (Correct answer)
- Changing the ventilator circuit every 24 hours
- Routine prophylactic antifungal therapy in all intubated patients
- Replacing HME filters with heated humidifiers to reduce circuit resistance
Correct answer: Maintaining the head of bed at 30–45 degrees to reduce aspiration
Semi-recumbent positioning at 30–45° is supported by randomised evidence to reduce aspiration and is a core component of ventilator care bundles.
Question 6: In inverse ratio ventilation (IRV), the inspiratory-to-expiratory ratio is set to:
- Greater than 1:1 (e.g., 2:1 or 3:1) (Correct answer)
- Less than 1:2 (e.g., 1:3 or 1:4)
- Exactly 1:1 to balance breath phases equally
- Greater than 1:4 to maximise expiratory time
Correct answer: Greater than 1:1 (e.g., 2:1 or 3:1)
IRV prolongs inspiratory time beyond expiratory time (I:E >1:1) to recruit atelectatic lung and build intrinsic PEEP, improving oxygenation in refractory ARDS.
Question 7: The primary mechanism by which recruitment maneuvers improve gas exchange in ARDS is:
- Transiently increasing airway pressure to re-open collapsed alveoli and restore functional residual capacity (Correct answer)
- Removing excess pulmonary oedema fluid through suction
- Improving cardiac output to increase mixed venous oxygen saturation
- Reducing pulmonary vascular resistance to lower right heart afterload
Correct answer: Transiently increasing airway pressure to re-open collapsed alveoli and restore functional residual capacity
Recruitment maneuvers use a sustained or stepwise increase in airway pressure to overcome the critical opening pressure of atelectatic alveoli.
FFICM Respiratory Management and Mechanical Ventilation 2
Which combination of criteria most appropriately indicates readiness to perform a spontaneous breathing trial (SBT)?