CRE Respiratory Therapy & Intervention Techniques 2 — Questions and Answers
Question 1: When setting up a small-volume nebulizer (SVN), what is the optimal flow rate to drive the nebulizer for most medications?
- 2–4 L/min
- 6–8 L/min (Correct answer)
- 10–12 L/min
- 14–16 L/min
Correct answer: 6–8 L/min
A flow rate of 6–8 L/min is recommended to produce the optimal particle size (1–5 µm) for alveolar deposition.
Question 2: A patient with COPD receives ipratropium bromide via MDI. What is the primary mechanism of action of this bronchodilator?
- Beta-2 adrenergic agonism
- Anticholinergic (muscarinic) blockade (Correct answer)
- Phosphodiesterase inhibition
- Leukotriene receptor antagonism
Correct answer: Anticholinergic (muscarinic) blockade
Ipratropium is an anticholinergic agent that blocks muscarinic receptors, reducing bronchoconstriction caused by parasympathetic stimulation.
Question 3: Which chest physiotherapy technique uses a mechanical device applied externally to the thorax to generate oscillatory pressure and mobilize secretions?
- Directed cough
- High-frequency chest wall oscillation (HFCWO) (Correct answer)
- Incentive spirometry
- Pursed-lip breathing
Correct answer: High-frequency chest wall oscillation (HFCWO)
HFCWO devices (e.g., the Vest) apply rapid compressions to the chest wall to thin and mobilize mucus toward the central airways.
Question 4: A mechanically ventilated patient has a plateau pressure of 32 cmH₂O and a PEEP of 8 cmH₂O. What is the driving pressure?
- 8 cmH₂O
- 24 cmH₂O (Correct answer)
- 32 cmH₂O
- 40 cmH₂O
Correct answer: 24 cmH₂O
Driving pressure = plateau pressure − PEEP = 32 − 8 = 24 cmH₂O; values above 15 cmH₂O are associated with higher mortality.
Question 5: During heliox therapy for upper airway obstruction, which helium-to-oxygen mixture is most commonly used when the patient requires supplemental oxygen?
- 80:20 He:O₂
- 70:30 He:O₂ (Correct answer)
- 60:40 He:O₂
- 50:50 He:O₂
Correct answer: 70:30 He:O₂
70:30 He:O₂ (70% helium, 30% oxygen) provides adequate oxygen delivery while maintaining enough helium to reduce turbulent flow.
Question 6: Which parameter best reflects the work the respiratory muscles must perform against intrinsic PEEP (auto-PEEP) in a spontaneously breathing patient on mechanical ventilation?
- Peak inspiratory pressure
- Mean airway pressure
- The trigger effort required to initiate inspiration (Correct answer)
- Compliance of the respiratory system
Correct answer: The trigger effort required to initiate inspiration
Auto-PEEP raises the threshold the patient must overcome to trigger a breath; excess effort to trigger indicates significant auto-PEEP.
Question 7: A patient with status asthmaticus is placed on mechanical ventilation with a respiratory rate of 12 and an I:E ratio of 1:4. Why is the prolonged expiratory time important?
- It reduces mean airway pressure to prevent barotrauma
- It allows full exhalation to minimize air trapping and auto-PEEP (Correct answer)
- It increases tidal volume delivery
- It improves alveolar recruitment
Correct answer: It allows full exhalation to minimize air trapping and auto-PEEP
Prolonged expiratory time allows adequate emptying of obstructed airways, reducing dynamic hyperinflation and the risk of tension pneumothorax.
CRE Respiratory Therapy & Intervention Techniques 2
When setting up a small-volume nebulizer (SVN), what is the optimal flow rate to drive the nebulizer for most medications?