RRT RRT Knowledge 4 — Questions and Answers
Question 1: A 32-week premature neonate presents with grunting, nasal flaring, and retractions within 2 hours of birth. Chest X-ray shows diffuse bilateral ground-glass opacities. The MOST likely diagnosis is:
- Meconium aspiration syndrome
- Transient tachypnea of the newborn
- Neonatal respiratory distress syndrome (RDS) (Correct answer)
- Congenital diaphragmatic hernia
Correct answer: Neonatal respiratory distress syndrome (RDS)
Neonatal RDS is caused by surfactant deficiency in premature infants and presents with early respiratory distress and bilateral ground-glass infiltrates on X-ray.
Question 2: Which parameter BEST reflects a patient's alveolar ventilation?
- Minute ventilation (VE)
- PaCO2 (Correct answer)
- PaO2
- End-tidal CO2 (EtCO2)
Correct answer: PaCO2
PaCO2 is inversely proportional to alveolar ventilation and is the gold standard measure of the adequacy of ventilation.
Question 3: When using a helium-oxygen (heliox) mixture to treat upper airway obstruction, the MOST appropriate concentration is:
- 20% He / 80% O2
- 40% He / 60% O2
- 70% He / 30% O2 (Correct answer)
- 80% He / 20% O2
Correct answer: 70% He / 30% O2
A 70% helium / 30% oxygen mixture provides the optimal balance of low gas density for improved flow while delivering sufficient FiO2.
Question 4: A patient has a total lung capacity (TLC) of 6.0 L, a residual volume (RV) of 2.4 L, and an RV/TLC ratio of 40%. This pattern is MOST consistent with:
- Normal lung function
- Obstructive lung disease (Correct answer)
- Restrictive lung disease
- Mixed obstructive-restrictive disease
Correct answer: Obstructive lung disease
An elevated RV/TLC ratio above 35% indicates air trapping characteristic of obstructive lung disease such as emphysema or severe asthma.
Question 5: The recommended initial tidal volume setting for a mechanically ventilated patient with ARDS is:
- 4–6 mL/kg predicted body weight
- 6–8 mL/kg predicted body weight (Correct answer)
- 10–12 mL/kg predicted body weight
- 12–15 mL/kg actual body weight
Correct answer: 6–8 mL/kg predicted body weight
The ARDSNet protocol recommends 6 mL/kg predicted body weight (PBW), with a range of 4–8 mL/kg PBW to limit volutrauma.
Question 6: A patient has the following ABG: pH 7.35, PaCO2 55 mmHg, HCO3 30 mEq/L. This result is MOST consistent with:
- Acute respiratory acidosis
- Chronic respiratory acidosis (compensated) (Correct answer)
- Metabolic alkalosis with respiratory compensation
- Mixed respiratory and metabolic acidosis
Correct answer: Chronic respiratory acidosis (compensated)
A near-normal pH with elevated PaCO2 and elevated HCO3 indicates chronic respiratory acidosis with full metabolic compensation (1 mEq/L HCO3 rise per 10 mmHg PaCO2 rise).
Question 7: Which maneuver should the respiratory therapist perform FIRST when a ventilated patient develops acute desaturation?
- Increase PEEP by 5 cm H2O
- Manually ventilate with 100% oxygen and assess the patient (Correct answer)
- Obtain an arterial blood gas
- Suction the endotracheal tube
Correct answer: Manually ventilate with 100% oxygen and assess the patient
Disconnecting the patient from the ventilator and manually ventilating with 100% O2 allows immediate assessment of lung compliance and rules out ventilator malfunction.
RRT RRT Knowledge 4
A 32-week premature neonate presents with grunting, nasal flaring, and retractions within 2 hours of birth.
Chest X-ray shows diffuse bilateral ground-glass opacities.
The MOST likely diagnosis is: