RRT RRT Knowledge 2 — Questions and Answers
Question 1: A patient with ARDS on mechanical ventilation has a PaO2/FiO2 ratio of 85. According to the Berlin Definition, this classifies as which severity?
- Mild ARDS
- Moderate ARDS
- Severe ARDS (Correct answer)
- Not ARDS
Correct answer: Severe ARDS
A PaO2/FiO2 ratio less than 100 mmHg with PEEP ≥5 cm H2O classifies as severe ARDS per the Berlin Definition.
Question 2: Which ventilator waveform pattern indicates auto-PEEP (intrinsic PEEP) is present?
- Flow fails to return to zero before next breath (Correct answer)
- Pressure rises sharply at end of inspiration
- Tidal volume decreases with each breath
- Plateau pressure exceeds peak pressure
Correct answer: Flow fails to return to zero before next breath
Auto-PEEP occurs when expiratory flow does not return to zero baseline before the next breath begins, indicating gas trapping.
Question 3: A patient receiving BiPAP at IPAP 14 / EPAP 6 cm H2O has an effective pressure support of:
- 6 cm H2O
- 8 cm H2O (Correct answer)
- 14 cm H2O
- 20 cm H2O
Correct answer: 8 cm H2O
Effective pressure support on BiPAP equals IPAP minus EPAP, so 14 − 6 = 8 cm H2O.
Question 4: When performing a slow vital capacity (SVC) maneuver, the patient is instructed to:
- Exhale as forcefully and quickly as possible
- Inhale maximally then exhale slowly and completely (Correct answer)
- Inhale and exhale at tidal breathing pace for 30 seconds
- Pant rapidly for 12 seconds then exhale fully
Correct answer: Inhale maximally then exhale slowly and completely
SVC requires a maximal inhalation followed by a slow, complete exhalation without forced effort, minimizing dynamic airway compression.
Question 5: Which blood gas result is consistent with acute respiratory alkalosis?
- pH 7.28, PaCO2 58, HCO3 26
- pH 7.52, PaCO2 28, HCO3 22 (Correct answer)
- pH 7.38, PaCO2 40, HCO3 24
- pH 7.30, PaCO2 42, HCO3 16
Correct answer: pH 7.52, PaCO2 28, HCO3 22
A pH above 7.45 with a low PaCO2 and near-normal HCO3 indicates acute respiratory alkalosis (hyperventilation without renal compensation).
Question 6: A size 8.0 endotracheal tube has an internal diameter of 8 mm. What is its approximate resistance compared to a 7.0 tube?
- Resistance is higher in the 8.0 tube
- Resistance is lower in the 8.0 tube (Correct answer)
- Resistance is equal between both sizes
- Resistance depends only on tube length
Correct answer: Resistance is lower in the 8.0 tube
Airway resistance is inversely proportional to the fourth power of the radius (Poiseuille's Law), so the larger 8.0 mm tube has significantly lower resistance.
Question 7: During a spontaneous breathing trial (SBT), which finding is the MOST reliable predictor of successful extubation?
- Rapid Shallow Breathing Index (RSBI) below 105 (Correct answer)
- Heart rate below 100 bpm throughout SBT
- SpO2 above 95% on FiO2 0.40
- Absence of secretions for 2 hours prior
Correct answer: Rapid Shallow Breathing Index (RSBI) below 105
An RSBI (f/VT) below 105 breaths/min/L is the best validated predictor of successful extubation following an SBT.
RRT RRT Knowledge 2
A patient with ARDS on mechanical ventilation has a PaO2/FiO2 ratio of 85.
According to the Berlin Definition, this classifies as which severity?