NBRC Respiratory Therapist 4 — Questions and Answers
Question 1: Which finding on a flow-volume loop is most consistent with a fixed upper airway obstruction?
- Scooped-out expiratory limb
- Flattening of both the inspiratory and expiratory limbs (Correct answer)
- Flattening of the inspiratory limb only
- Normal loop with reduced peak flow
Correct answer: Flattening of both the inspiratory and expiratory limbs
Fixed upper airway obstruction (e.g., tracheal stenosis) limits flow equally in both directions, producing a flattened plateau on both limbs.
Question 2: A patient with asthma presents to the ED with SpO2 88%, wheezing, and inability to complete sentences. After two doses of albuterol, there is minimal improvement. What medication should be added next?
- Inhaled fluticasone
- Systemic corticosteroids (IV methylprednisolone)
- Inhaled ipratropium and systemic magnesium sulfate (Correct answer)
- Subcutaneous epinephrine only
Correct answer: Inhaled ipratropium and systemic magnesium sulfate
In severe acute asthma refractory to initial beta-agonist therapy, adding inhaled anticholinergics and IV magnesium sulfate provides additive bronchodilation.
Question 3: When using high-frequency oscillatory ventilation (HFOV), oxygenation is primarily controlled by adjusting:
- Frequency (Hz)
- Mean airway pressure (mPaw) (Correct answer)
- Amplitude (ΔP)
- Inspiratory time percentage
Correct answer: Mean airway pressure (mPaw)
On HFOV, mean airway pressure determines lung recruitment and FRC, which is the primary determinant of oxygenation.
Question 4: A patient's capnography waveform shows an exponential decrease in end-tidal CO2 during CPR. What does this most likely indicate?
- Hyperventilation by the provider
- Return of spontaneous circulation (ROSC)
- Esophageal intubation (Correct answer)
- Increased metabolic rate
Correct answer: Esophageal intubation
A sudden, exponential drop in ETCO2 to near-zero values during CPR strongly suggests esophageal intubation, as no CO2 is produced in the GI tract.
Question 5: Which calculation correctly determines alveolar oxygen tension (PAO2) using the alveolar air equation?
- PAO2 = (FiO2 × 713) - (PaCO2 / 0.8) (Correct answer)
- PAO2 = PaO2 + PaCO2
- PAO2 = FiO2 × PB - PaCO2
- PAO2 = (PB - 47) × FiO2 - PaCO2 × 1.2
Correct answer: PAO2 = (FiO2 × 713) - (PaCO2 / 0.8)
The alveolar air equation is PAO2 = (FiO2 × [PB - PH2O]) - (PaCO2/RQ), which at sea level simplifies to (FiO2 × 713) - (PaCO2/0.8).
Question 6: A premature infant at 28 weeks gestation is intubated for respiratory distress syndrome. After surfactant administration, the RT should reassess ventilator settings because:
- Surfactant increases airway resistance significantly
- Lung compliance improves rapidly, risking volutrauma if pressures are not reduced (Correct answer)
- FiO2 requirements typically increase after surfactant
- The ETT may become dislodged during administration
Correct answer: Lung compliance improves rapidly, risking volutrauma if pressures are not reduced
Surfactant rapidly improves lung compliance, so if inspiratory pressures are not promptly reduced, the delivered tidal volume rises and can cause volutrauma.
Question 7: During a 6-minute walk test, a patient's SpO2 drops from 96% to 84%. The appropriate clinical response is to:
- Continue the test and document the desaturation
- Stop the test and administer supplemental oxygen (Correct answer)
- Increase walking pace to complete the test faster
- Repeat the test the following day with supplemental oxygen
Correct answer: Stop the test and administer supplemental oxygen
Exercise-induced desaturation to ≤88% (or ≤84% by some protocols) is a safety endpoint requiring test termination and supplemental oxygen.
NBRC Respiratory Therapist 4
Which finding on a flow-volume loop is most consistent with a fixed upper airway obstruction?