RRT RRT MCQ 5 — Questions and Answers
Question 1: A 70 kg patient on volume control ventilation has a tidal volume of 500 mL, rate of 14, I:E ratio of 1:2, and peak flow of 60 L/min. What is the inspiratory time?
- 0.33 seconds
- 0.50 seconds (Correct answer)
- 1.0 seconds
- 1.43 seconds
Correct answer: 0.50 seconds
Inspiratory time = tidal volume (L) ÷ peak flow (L/s) = 0.5 L ÷ (60/60 L/s) = 0.5 seconds.
Question 2: In a patient with status asthmaticus on mechanical ventilation, auto-PEEP is detected at 12 cmH2O. The BEST immediate intervention is:
- Increase respiratory rate to decrease PaCO2
- Decrease tidal volume and respiratory rate to allow more expiratory time (Correct answer)
- Add extrinsic PEEP equal to the auto-PEEP level
- Perform manual hyperinflation to release trapped gas
Correct answer: Decrease tidal volume and respiratory rate to allow more expiratory time
Reducing rate and tidal volume lengthens expiratory time, allowing trapped gas to exhale and reducing dynamic hyperinflation and auto-PEEP.
Question 3: A patient's spontaneous breathing trial (SBT) is terminated early. Which finding is the MOST valid reason to stop the trial?
- Respiratory rate of 22 breaths/min
- SpO2 of 93% on 40% FiO2
- Systolic blood pressure of 155 mmHg (up from 130 mmHg baseline)
- Rapid shallow breathing index (RSBI) of 120 (Correct answer)
Correct answer: Rapid shallow breathing index (RSBI) of 120
An RSBI (f/VT) ≥105 predicts SBT failure; a value of 120 indicates rapid, shallow breathing pattern consistent with respiratory muscle fatigue.
Question 4: Which finding confirms tracheal (not esophageal) intubation after orotracheal intubation?
- Rise and fall of the chest with ventilation
- Bilateral breath sounds on auscultation
- Continuous colorimetric end-tidal CO2 detection over 6 breaths (Correct answer)
- Absence of gastric sounds over the epigastrium
Correct answer: Continuous colorimetric end-tidal CO2 detection over 6 breaths
Continuous colorimetric or capnographic ETCO2 detection persisting over ≥6 breaths is the gold-standard confirmation of tracheal intubation.
Question 5: A patient with pulmonary hypertension requires inhaled nitric oxide (iNO) therapy. The primary mechanism of action is:
- Systemic vasodilation reducing afterload on the right ventricle
- Selective pulmonary vasodilation by activating guanylate cyclase in vascular smooth muscle (Correct answer)
- Bronchodilation improving V/Q matching
- Inhibition of hypoxic pulmonary vasoconstriction reflexes
Correct answer: Selective pulmonary vasodilation by activating guanylate cyclase in vascular smooth muscle
iNO diffuses into pulmonary vascular smooth muscle, activates soluble guanylate cyclase, raises cGMP, and causes selective pulmonary vasodilation without systemic effects.
Question 6: A patient with a tracheostomy develops subcutaneous emphysema around the stoma. The MOST appropriate first action is:
- Deflate the tracheostomy cuff and assess for air leak
- Immediately replace the tracheostomy with an oral endotracheal tube
- Verify tracheostomy tube position with bronchoscopy or chest X-ray (Correct answer)
- Increase cuff pressure to 30 cmH2O to seal the leak
Correct answer: Verify tracheostomy tube position with bronchoscopy or chest X-ray
Subcutaneous emphysema around a tracheostomy suggests tube malposition or paratracheal placement; tube position must be verified immediately before adjusting cuff pressure.
Question 7: During cardiopulmonary resuscitation (CPR), what ventilation-to-compression ratio is recommended for a single rescuer performing adult CPR without an advanced airway?
- 1 breath per 5 compressions
- 2 breaths per 30 compressions (Correct answer)
- 1 breath per 15 compressions
- Continuous compressions without ventilation
Correct answer: 2 breaths per 30 compressions
Current AHA guidelines recommend a 30:2 compression-to-ventilation ratio for single-rescuer adult CPR prior to advanced airway placement.
RRT RRT MCQ 5
A 70 kg patient on volume control ventilation has a tidal volume of 500 mL, rate of 14, I:E ratio of 1:2, and peak flow of 60 L/min.
What is the inspiratory time?