RRT RRT 5 — Questions and Answers
Question 1: Which of the following correctly describes high-frequency oscillatory ventilation (HFOV)?
- Delivers large tidal volumes at low rates
- Uses tidal volumes smaller than anatomical dead space at very high frequencies (Correct answer)
- Provides pressure support with each spontaneous breath
- Requires patient to trigger every breath
Correct answer: Uses tidal volumes smaller than anatomical dead space at very high frequencies
HFOV delivers very small tidal volumes (1-3 mL/kg) at frequencies of 3-15 Hz, keeping mean airway pressure constant while oscillating around it.
Question 2: A patient with suspected pulmonary embolism has which of the following MOST typical ABG findings?
- Hypercapnia with metabolic acidosis
- Hypoxemia with respiratory alkalosis (low PaCO2) (Correct answer)
- Hypoxemia with respiratory acidosis
- Normal ABG with elevated PaCO2
Correct answer: Hypoxemia with respiratory alkalosis (low PaCO2)
PE typically causes hypoxemia from V/Q mismatch and reflexive hyperventilation leading to low PaCO2 and respiratory alkalosis.
Question 3: Which of the following is the MOST effective method to confirm correct endotracheal tube placement after intubation?
- Auscultation of breath sounds bilaterally
- Chest rise observation
- Continuous waveform capnography (Correct answer)
- Fogging of the ETT
Correct answer: Continuous waveform capnography
Continuous waveform capnography (ETCO2) with a consistent rectangular waveform is the gold standard for confirming and monitoring ETT placement.
Question 4: When performing a helium dilution test for measuring functional residual capacity (FRC), what is the underlying principle?
- Helium is absorbed into the bloodstream, causing pressure changes
- A known concentration of helium equilibrates with lung gas allowing calculation of FRC (Correct answer)
- Nitrogen washout measures helium uptake
- Helium's density changes are measured by spirometry
Correct answer: A known concentration of helium equilibrates with lung gas allowing calculation of FRC
In helium dilution, a known amount of helium equilibrates between the spirometer and lungs; the final diluted concentration allows FRC calculation via conservation of mass.
Question 5: Which condition is MOST likely to cause a decreased diffusing capacity (DLCO)?
- Obesity
- Polycythemia
- Pulmonary fibrosis (Correct answer)
- Asthma
Correct answer: Pulmonary fibrosis
Pulmonary fibrosis thickens the alveolar-capillary membrane, impairing gas diffusion and reducing DLCO.
Question 6: Which of the following represents a normal mixed venous oxygen saturation (SvO2)?
- 95-100%
- 85-90%
- 60-80% (Correct answer)
- 40-55%
Correct answer: 60-80%
Normal SvO2 is 60-80%, reflecting adequate tissue oxygen delivery relative to consumption; values below 60% suggest inadequate delivery or increased extraction.
Question 7: A patient receiving heliox therapy for croup would MOST likely receive which mixture?
- 50% helium / 50% oxygen
- 70% helium / 30% oxygen (Correct answer)
- 80% helium / 20% oxygen
- 60% helium / 40% oxygen
Correct answer: 70% helium / 30% oxygen
70:30 heliox is the most commonly used mixture for upper airway obstruction, balancing low-density gas benefit with adequate oxygen delivery.
RRT RRT 5
Which of the following correctly describes high-frequency oscillatory ventilation (HFOV)?