CPAP, Capnography, and Ventilatory Support Practice Questions

30 multiple-choice questions on CPAP, capnography, and ventilatory support for paramedic and EMT students, from Chapter 17 (Respiratory Emergencies). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

30 practice questions

1. Why is a closed (in-line) suction catheter preferred for suctioning an intubated patient on PEEP?

   1. A. It allows deeper suctioning into the alveoli
   2. B. It needs no oxygen before or after suctioning
   3. C. It suctions without disconnecting, so PEEP is kept
   4. D. It can be left in place inside the tube between uses
   Show answer

   Answer: C. It suctions without disconnecting, so PEEP is kept

   A closed suction catheter sits in a sleeve attached to the circuit, so the tube is suctioned without disconnecting the ventilator, preserving PEEP and oxygenation and limiting crew exposure. It does not reach the alveoli. Patients may still need oxygenation before and after suctioning. The catheter is pulled back into its sleeve after each use so it does not block the tube.

2. An intubated patient is on a transport ventilator mode that gives breaths only when he triggers them. After a dose of fentanyl, he stops breathing. Which setting protects him?

   1. A. The high-pressure alarm limit
   2. B. The PEEP level
   3. C. The apnea backup rate
   4. D. The FiO2 setting
   Show answer

   Answer: C. The apnea backup rate

   In spontaneous modes such as CPAP with pressure support, the ventilator gives no breaths unless the patient triggers them, so an apnea alarm with a backup rate is needed. The high-pressure limit protects against high airway pressure. PEEP keeps alveoli open but does not ventilate. FiO2 sets the oxygen concentration, not the number of breaths.

3. A sedated patient on nasal-oral capnography has a flat line, but his chest and abdomen are moving with effort. What should you do?

   1. A. Open his airway with a jaw thrust
   2. B. Replace the capnography sampling line first
   3. C. Give naloxone for apnea
   4. D. Turn up the oxygen and observe
   Show answer

   Answer: A. Open his airway with a jaw thrust

   Breathing effort without exhaled CO2 means the upper airway is obstructed; open it with a head tilt-chin lift or jaw thrust and an adjunct. Replacing the line wastes time when the problem is the airway. He is not apneic, so naloxone is not the first step. More oxygen cannot pass a blocked airway.

4. You are assisting a tiring COPD patient's breathing with a BVM while he is still breathing on his own. How should you deliver breaths?

   1. A. Squeeze as fast as possible, ignoring his effort
   2. B. Squeeze during his exhalations
   3. C. Squeeze gently as he begins each inhalation
   4. D. Give one large breath each 30 seconds
   Show answer

   Answer: C. Squeeze gently as he begins each inhalation

   Assisted breaths should be timed with the patient's own inspiration so they add to his effort, with gentle volume. Ignoring his effort causes stacking and gastric inflation. Bagging during exhalation fights his breathing and traps air. One breath every 30 seconds is far too slow.

5. After PEEP is raised from 5 to 12 cm H2O on a dehydrated ventilated patient, her BP falls from 118/70 to 84/50. What is the likely cause?

   1. A. A sudden allergic reaction to the added oxygen
   2. B. Higher chest pressure reducing venous return
   3. C. A cuff leak around the ET tube
   4. D. Low blood sugar from fasting
   Show answer

   Answer: B. Higher chest pressure reducing venous return

   PEEP raises pressure in the chest, which reduces blood return to the heart, especially in a dehydrated patient; lower the PEEP and give fluid per protocol. Oxygen allergy does not exist. A cuff leak lowers airway pressure and does not cause hypotension. Hypoglycemia does not explain a drop right after the PEEP change.

6. Before a 45-minute transport on a flow-driven CPAP device, what should you check first?

   1. A. That the patient has an IV line in place
   2. B. That the patient can lie flat
   3. C. That a nebulizer is attached in line
   4. D. That you have enough oxygen for the trip
   Show answer

   Answer: D. That you have enough oxygen for the trip

   Many flow-driven EMS CPAP devices use 15 L/min or more of oxygen, so a long transport can empty a portable cylinder; confirm the main supply or carry spares. Patients on CPAP sit up. CPAP does not require an IV line or an in-line nebulizer before it can be used.

7. A pulmonary edema patient has improved on CPAP. At the hospital, the nurse asks you to take it off while they set up their BiPAP. What is the best response?

   1. A. Remove it now, since he has improved
   2. B. Remove it and use a nasal cannula for a short while
   3. C. Remove it so he can describe his symptoms
   4. D. Keep CPAP on until their device is ready to switch
   Show answer

   Answer: D. Keep CPAP on until their device is ready to switch

   Removing positive pressure can let the alveoli flood again within minutes, so keep CPAP on until the next device is ready for a direct switch. Improvement shows that CPAP is working. A nasal cannula gives no positive pressure. History can be taken without removing the mask.

8. Which patient in respiratory distress should not receive CPAP?

   1. A. A woman with pulmonary edema and a BP of 150/90
   2. B. A man with facial fractures after an assault
   3. C. A man with COPD who is alert and following commands
   4. D. A woman with near-drowning who is alert
   Show answer

   Answer: B. A man with facial fractures after an assault

   Facial trauma prevents a mask seal and risks forcing air through fractures, so it is a contraindication. Pulmonary edema with adequate BP and an alert COPD patient are classic CPAP indications. An alert, cooperative near-drowning patient with hypoxemia can also benefit from CPAP.

9. A patient is on a pressure-control ventilator setting. Over 20 minutes, his tidal volume falls from 450 to 280 mL with no settings changed. What does this suggest?

   1. A. His lungs or airways are harder to inflate
   2. B. The ventilator is working normally
   3. C. His lungs have become easier to inflate now
   4. D. The oxygen tank is getting low
   Show answer

   Answer: A. His lungs or airways are harder to inflate

   In pressure control the ventilator delivers a set pressure, so the volume falls when compliance worsens (edema, pneumothorax) or resistance rises (secretions, bronchospasm); check the patient and the tube. A large fall is not normal. Better compliance would raise the volume. Oxygen supply affects FiO2, not the delivered volume.

10. What is a main advantage of high-flow nasal cannula over a standard nasal cannula?

    1. A. It provides full ventilation for apneic patients
    2. B. It can match the patient's own inspiratory flow
    3. C. It delivers a set tidal volume
    4. D. It needs no humidifier at high flow
    Show answer

    Answer: B. It can match the patient's own inspiratory flow

    Heated, humidified high-flow systems deliver up to about 60 L/min, enough to match a distressed patient's inspiratory flow so the set FiO2 is reliable, while flushing dead space and adding a small PEEP. They do not ventilate an apneic patient. They do not set a tidal volume, and the gas must be heated and humidified because high flows of dry gas injure the nasal lining.

11. A CPAP patient is still hypoxic at 10 cm H2O. Why do many EMS protocols cap CPAP at about 15 cm H2O?

    1. A. They risk gastric inflation and hypotension
    2. B. They raise CO2 by rebreathing
    3. C. They often trigger bronchospasm
    4. D. They are reserved for patients who have asthma
    Show answer

    Answer: A. They risk gastric inflation and hypotension

    Above about 15 cm H2O, air is more likely to enter the stomach (risking vomiting and aspiration), venous return falls further and causes hypotension, and the risk of barotrauma rises. Higher CPAP is not reserved for asthma, and asthma is not a group that needs higher pressures. Higher CPAP does not cause CO2 rebreathing or bronchospasm.

12. Which patient is the best candidate for CPAP?

    1. A. An alert patient in pulmonary edema
    2. B. A patient with a tension pneumothorax
    3. C. A hypotensive patient in septic shock
    4. D. An apneic patient after an overdose
    Show answer

    Answer: A. An alert patient in pulmonary edema

    CPAP requires spontaneous breathing, an intact airway, and adequate blood pressure. It is ideal for alert patients with CHF or COPD exacerbations.

13. Which finding is a contraindication to CPAP?

    1. A. Respiratory rate of 26/min
    2. B. SpO2 of 88% on high-flow O2
    3. C. Wheezes in both lungs
    4. D. Systolic BP below 90 mmHg
    Show answer

    Answer: D. Systolic BP below 90 mmHg

    CPAP raises intrathoracic pressure and can decrease venous return, worsening hypotension. Other contraindications include apnea, altered mental status, and vomiting.

14. You are setting up a transport ventilator for a newly intubated adult with normal lungs. What initial PEEP is typical?

    1. A. 20 cm H2O
    2. B. 0 cm H2O
    3. C. 15 cm H2O
    4. D. 5 cm H2O
    Show answer

    Answer: D. 5 cm H2O

    About 5 cm H2O of PEEP is the usual starting point to prevent alveolar collapse and preserve lung volume. Twenty and 15 cm H2O are high levels reserved for severe hypoxemia and risk hypotension. Zero PEEP lets small airways collapse.

15. A patient is on BiPAP with an inspiratory pressure (IPAP) of 14 cm H2O and an expiratory pressure (EPAP) of 6 cm H2O. How much pressure support does each breath receive above EPAP?

    1. A. 8 cm H2O
    2. B. 20 cm H2O
    3. C. 14 cm H2O
    4. D. 6 cm H2O
    Show answer

    Answer: A. 8 cm H2O

    Pressure support is the difference between IPAP and EPAP: 14 - 6 = 8 cm H2O. This boost helps move air and lower CO2, while the EPAP of 6 acts like PEEP. 20 adds the two values. 14 is the IPAP itself. 6 is the EPAP.

16. The difference between CPAP and BiPAP is that BiPAP:

    1. A. Gives a set tidal volume
    2. B. Uses one higher pressure
    3. C. Uses two pressure levels
    4. D. Requires an ET tube
    Show answer

    Answer: C. Uses two pressure levels

    BiPAP provides a higher inspiratory pressure and a lower expiratory pressure, helping ventilation as well as oxygenation. It does not set a tidal volume, it does not use a single higher pressure, and it needs no ET tube.

17. In a ventilated ARDS patient, what plateau pressure should be kept at or below?

    1. A. 50 cm H2O
    2. B. 10 cm H2O
    3. C. 30 cm H2O
    4. D. 40 cm H2O
    Show answer

    Answer: C. 30 cm H2O

    Lung-protective ventilation aims to keep the plateau pressure at or below 30 cm H2O to limit alveolar overdistention. Pressures of 40 to 50 cm H2O injure the lungs. A plateau of 10 is not a realistic limit for stiff lungs.

18. You are moving an intubated adult and need to flex her neck to reposition her. How does neck flexion affect the ET tube?

    1. A. It pulls the tube up toward the vocal cords
    2. B. It has no effect on tube position
    3. C. It deflates the tube cuff
    4. D. It pushes the tube deeper toward the carina
    Show answer

    Answer: D. It pushes the tube deeper toward the carina

    The tip of the tube moves in the direction the chin moves: flexion pushes it deeper (risking a mainstem intubation) and extension pulls it out toward the cords. Movement does affect position, which is why the head is kept neutral and the tube rechecked after moves. Neck movement does not deflate the cuff.

19. An intubated patient's capnography waveform has gradually flattened, but his chest rise and breath sounds are unchanged and his SpO2 is stable. What should you check?

    1. A. Whether he needs to be reintubated
    2. B. The sampling line for water or secretions
    3. C. Whether he is in cardiac arrest
    4. D. Whether the tube has moved into the esophagus
    Show answer

    Answer: B. The sampling line for water or secretions

    With good chest rise, equal breath sounds, and stable SpO2, a gradually fading waveform suggests a sampling problem such as moisture or secretions in the line or adapter. Reintubation is not indicated when the tube is clearly working. A patient in arrest would lose his pulse and SpO2. An esophageal tube would not give good chest rise and breath sounds.

20. After moving an intubated patient from the bed to your stretcher, what should you do next?

    1. A. Deflate and reinflate the cuff
    2. B. Reconfirm tube placement
    3. C. Increase the tidal volume
    4. D. Remove the bite block
    Show answer

    Answer: B. Reconfirm tube placement

    Any move can dislodge the tube, so reconfirm placement after every transfer with waveform capnography, chest rise, and breath sounds. Deflating the cuff risks aspiration. Changing the tidal volume does not check position. The bite block protects the tube from being bitten.

21. Why can EtCO2 be useful in a patient with sepsis?

    1. A. It replaces blood pressure checks
    2. B. Low values may reflect poor perfusion
    3. C. It measures oxygen saturation
    4. D. High values confirm a bacterial cause
    Show answer

    Answer: B. Low values may reflect poor perfusion

    EtCO2 depends on perfusion. Low EtCO2 in sepsis may correlate with metabolic acidosis and elevated lactate.

22. During a long transfer, water collects in the ventilator tubing, and the circuit rattles with each breath. What should you do?

    1. A. Tip the tubing so it drains to the tube
    2. B. Ignore it; it does not affect ventilation
    3. C. Drain the water away from the patient
    4. D. Remove the PEEP to dry out the circuit
    Show answer

    Answer: C. Drain the water away from the patient

    Condensation in the circuit adds resistance, can trigger false breaths and alarms, and can be washed into the airway, so drain it into a water trap or away from the patient without letting it run toward the ET tube. Draining it toward the tube risks aspiration. It does affect ventilation. PEEP has nothing to do with condensation.

23. On volume control, a ventilated patient's peak pressure rises from 24 to 42 cm H2O, but the plateau pressure stays at 20. What does this suggest?

    1. A. Stiffer lungs, as in pulmonary edema
    2. B. A normal change with no concern
    3. C. A leak around the tube cuff
    4. D. Higher airway resistance
    Show answer

    Answer: D. Higher airway resistance

    The peak-plateau difference reflects airway resistance, while the plateau reflects lung and chest wall compliance. A high peak with an unchanged plateau points to resistance: secretions, a kinked or bitten tube, or bronchospasm. Stiffer lungs would raise the plateau too. A rise of this size is not normal. A cuff leak lowers pressures.

24. A ventilated patient is "fighting the ventilator," with coughing and high-pressure alarms. What should you do before giving more sedation?

    1. A. Give a paralytic without sedation
    2. B. Look for a cause such as hypoxia
    3. C. Raise the tidal volume to match him
    4. D. Increase the PEEP to 15 cm H2O
    Show answer

    Answer: B. Look for a cause such as hypoxia

    Distress on the ventilator can come from hypoxia, a displaced or blocked tube, pneumothorax, pain, or poor settings, so look for these before sedating. A paralytic without sedation is inhumane and hides the problem. Raising the tidal volume or PEEP raises airway pressure further and can cause barotrauma or hypotension without finding the cause.

25. A CPAP patient's pressure keeps dropping, and you hear air hissing around the mask. What should you do first?

    1. A. Raise the CPAP to 20 cm H2O to compensate
    2. B. Remove CPAP for a nonrebreather
    3. C. Lay the patient flat
    4. D. Refit the straps or change the mask
    Show answer

    Answer: D. Refit the straps or change the mask

    A leak at the mask is the most common reason CPAP fails to hold pressure; refit the straps or change the mask size. Raising the pressure increases the leak and gastric inflation. Removing CPAP gives up the treatment. Lying flat worsens dyspnea.

26. A COPD patient has been on noninvasive ventilation for 45 minutes. Which finding indicates it is failing?

    1. A. His respiratory rate has fallen from 32 to 22
    2. B. His SpO2 has risen from 84% to 90%
    3. C. He is drowsier and his EtCO2 is rising
    4. D. He is speaking in full sentences
    Show answer

    Answer: C. He is drowsier and his EtCO2 is rising

    Worsening drowsiness and rising CO2 after a fair trial of NIV mean it is not working, and he needs a decision about intubation. A falling rate, an improving SpO2 within target, and speaking in full sentences all show improvement.

27. What is the main advantage of noninvasive ventilation over intubation in eligible patients?

    1. A. Needs no monitoring
    2. B. Better airway protection
    3. C. Fewer complications
    4. D. Works in apnea
    Show answer

    Answer: C. Fewer complications

    CPAP and BiPAP avoid the risks of intubation such as ventilator-associated pneumonia and airway trauma, but they do not protect the airway.

28. A 20-kg child is placed on a transport ventilator. Using 6 to 8 mL/kg, which tidal volume range is appropriate?

    1. A. 200 to 300 mL
    2. B. 60 to 80 mL
    3. C. 320 to 400 mL
    4. D. 120 to 160 mL
    Show answer

    Answer: D. 120 to 160 mL

    Multiply weight by the range: 20 x 6 = 120 mL and 20 x 8 = 160 mL. 200 to 300 mL uses 10 to 15 mL/kg, which risks lung injury. 60 to 80 mL uses 3 to 4 mL/kg, too little to ventilate. 320 to 400 mL is an adult-sized breath for this child.

29. For a dyspneic patient starting noninvasive ventilation in the field, why is a full-face (oronasal) mask usually chosen over a nasal mask?

    1. A. Nasal masks give higher pressures
    2. B. Distressed patients mouth-breathe
    3. C. Full-face masks feel less confining
    4. D. Nasal masks raise aspiration risk
    Show answer

    Answer: B. Distressed patients mouth-breathe

    Patients in acute respiratory distress usually breathe through the mouth, so a nasal mask leaks air out of the mouth and loses pressure; an oronasal mask covers both. Nasal masks do not give higher pressures. Full-face masks feel more confining, not less, and they carry a higher aspiration risk than nasal masks if the patient vomits.

30. Which mask feature is essential for CPAP to work effectively?

    1. A. A reservoir bag
    2. B. An open side port
    3. C. A loose, comfortable fit
    4. D. A good mask seal
    Show answer

    Answer: D. A good mask seal

    CPAP depends on maintaining positive pressure, which requires a properly sized mask with a tight seal.