Oxygen Delivery and Ventilation Practice Questions

31 multiple-choice questions on Oxygen delivery and ventilation for paramedic and EMT students, from Chapter 16 (Airway Management). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

31 practice questions

1. What is the usual flow-rate range for a nasal cannula?

   1. A. 6 to 10 L/min
   2. B. 1 to 6 L/min
   3. C. 10 to 15 L/min
   4. D. 15 to 25 L/min
   Show answer

   Answer: B. 1 to 6 L/min

   A nasal cannula runs at 1 to 6 L/min, delivering roughly 24% to 44% oxygen. Higher flows mostly dry the mucosa unless a high-flow system is used.

2. A nonrebreather mask at 15 L/min with a properly inflated reservoir delivers an oxygen concentration of up to about:

   1. A. 90%
   2. B. 44%
   3. C. 70%
   4. D. 60%
   Show answer

   Answer: A. 90%

   A well-fitted nonrebreather can deliver up to about 90% oxygen. A nasal cannula tops out near 44%.

3. Before placing a nonrebreather mask on a patient, you should:

   1. A. Humidify the oxygen
   2. B. Remove the one-way valves
   3. C. Set flow to 4 L/min
   4. D. Fill the reservoir bag
   Show answer

   Answer: D. Fill the reservoir bag

   Pre-fill the reservoir so the patient's first breaths draw oxygen, and keep the flow high enough that the bag does not collapse on inhalation.

4. A 50-year-old with pneumonia and no lung disease is on a nonrebreather at 15 L/min, and his SpO2 is now 100%. What is the best action?

   1. A. Keep 15 L/min to build up an oxygen reserve
   2. B. Step oxygen down to keep SpO2 at 94% to 98%
   3. C. Remove the oxygen and recheck in an hour
   4. D. Start CPAP to recruit more alveoli
   Show answer

   Answer: B. Step oxygen down to keep SpO2 at 94% to 98%

   Oxygen is a drug that is titrated to a target. For most acutely ill adults the target is 94% to 98%, so wean him to a nasal cannula or a lower flow. Holding 100% adds hyperoxia without benefit. Stopping oxygen and waiting an hour risks unnoticed hypoxemia. He is oxygenating well and does not need CPAP.

5. During CPR on an intubated 3-year-old, how often should ventilations be given?

   1. A. 1 breath every 6 seconds
   2. B. 1 breath every 2 to 3 seconds
   3. C. 2 breaths after 15 compressions
   4. D. 1 breath every 10 seconds
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   Answer: B. 1 breath every 2 to 3 seconds

   Current AHA PALS guidance for a child with an advanced airway during CPR is 1 breath every 2 to 3 seconds (20 to 30 per minute) with continuous compressions. One breath every 6 seconds is the adult rate. The 15:2 pattern is for two-rescuer CPR without an advanced airway. One breath every 10 seconds is too slow.

6. A patient is on a nasal cannula at 4 L/min. About what FiO2 is he receiving?

   1. A. About 36%
   2. B. About 24%
   3. C. About 44%
   4. D. About 60%
   Show answer

   Answer: A. About 36%

   Each liter per minute by nasal cannula adds roughly 4% to room air's 21%: about 24% at 1 L, 28% at 2 L, 32% at 3 L, 36% at 4 L, and 44% at 6 L. 24% is the 1-L value, 44% the 6-L value, and 60% is beyond what a cannula can provide.

7. An adult with a pulse has inadequate breathing. At what rate should you deliver BVM ventilations?

   1. A. 1 breath every 3 seconds
   2. B. 1 breath every 2 seconds
   3. C. 1 breath every 6 seconds
   4. D. 1 breath every 10 seconds
   Show answer

   Answer: C. 1 breath every 6 seconds

   AHA recommends 1 breath every 6 seconds (10 per minute) for adults in respiratory arrest with a pulse.

8. During adult CPR with an advanced airway in place, how should ventilations be delivered?

   1. A. 1 every 6 s, nonstop CPR
   2. B. 2 breaths per 30 compressions
   3. C. 1 every 3 s, nonstop CPR
   4. D. 1 every 10 s, pause CPR
   Show answer

   Answer: A. 1 every 6 s, nonstop CPR

   With an advanced airway, compressions continue without pauses and one breath is given every 6 seconds (10 per minute).

9. For adult CPR without an advanced airway, the compression-to-ventilation ratio is:

   1. A. 15:2
   2. B. 30:2
   3. C. 5:1
   4. D. 30:1
   Show answer

   Answer: B. 30:2

   Without an advanced airway, adults receive 30 compressions followed by 2 breaths, regardless of the number of rescuers.

10. A 4-year-old has a pulse but is breathing only 6 times per minute. At what rate should you provide BVM ventilations?

    1. A. 1 breath every 8 to 10 seconds
    2. B. 1 breath every 2 to 3 seconds
    3. C. 1 breath every 1 second
    4. D. 1 breath every 6 seconds
    Show answer

    Answer: B. 1 breath every 2 to 3 seconds

    For infants and children with a pulse but inadequate breathing, AHA recommends 1 breath every 2 to 3 seconds (20 to 30 per minute).

11. Over what time should each rescue breath be delivered?

    1. A. Less than 0.5 second
    2. B. About 3 seconds
    3. C. About 2 seconds
    4. D. About 1 second
    Show answer

    Answer: D. About 1 second

    Each breath should take about 1 second. Faster, forceful breaths raise airway pressure and push air into the stomach.

12. How much volume should each BVM breath deliver to an adult?

    1. A. The full volume of the bag
    2. B. About 800 to 1,000 mL per breath
    3. C. Enough for visible chest rise
    4. D. About 200 mL per breath
    Show answer

    Answer: C. Enough for visible chest rise

    Give just enough to see the chest rise, roughly 500 to 600 mL. Larger volumes cause gastric distension and reduce venous return. Breaths of 800 to 1,000 mL or the full bag volume over-deliver and inflate the stomach, while 200 mL is too small to ventilate an adult.

13. You are ventilating a patient with a BVM and notice the abdomen steadily enlarging and bagging becoming harder. What is the most likely cause?

    1. A. Bronchospasm
    2. B. Right mainstem intubation
    3. C. Gastric distension
    4. D. A tension pneumothorax
    Show answer

    Answer: C. Gastric distension

    Excessive rate, volume, or pressure pushes air into the stomach, which raises the risk of regurgitation and limits lung expansion. Slow down and reduce volume.

14. A BVM connected to oxygen at 15 L/min with a reservoir attached can deliver an oxygen concentration of:

    1. A. About 50%
    2. B. About 75%
    3. C. About 21%
    4. D. Nearly 100%
    Show answer

    Answer: D. Nearly 100%

    With a reservoir and high-flow oxygen, a BVM delivers close to 100% oxygen. Without supplemental oxygen it delivers room air at 21%.

15. Why is two-rescuer BVM ventilation preferred over one-rescuer technique?

    1. A. Better mask seal
    2. B. Less gastric air
    3. C. Faster breath rate
    4. D. Lower oxygen use
    Show answer

    Answer: A. Better mask seal

    One rescuer can use both hands to seal the mask and lift the jaw while the other squeezes the bag, producing much more effective ventilation.

16. In the E-C clamp technique for holding a BVM mask, which fingers form the "C"?

    1. A. Ring and little fingers
    2. B. Index and middle fingers
    3. C. Middle and ring fingers
    4. D. Thumb and index finger
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    Answer: D. Thumb and index finger

    The thumb and index finger press the mask down (C) while the remaining three fingers lift the mandible (E).

17. Minutes after CPAP is started for pulmonary edema, the patient's distress suddenly worsens, breath sounds vanish on the left, and his BP drops to 80/50. What is most likely?

    1. A. Worsening pulmonary edema on the left
    2. B. A pneumothorax from positive pressure
    3. C. Bilateral air trapping from auto-PEEP
    4. D. A mucus plug in the left bronchus
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    Answer: B. A pneumothorax from positive pressure

    Sudden unilateral absent breath sounds with hypotension after positive pressure suggest a pneumothorax, possibly under tension. Stop CPAP, reassess, and decompress if signs of tension are present. Worsening edema causes crackles, not absent sounds on one side. Air trapping affects both lungs rather than silencing one side, and a mucus plug can quiet one side but does not cause sudden hypotension.

18. A patient with acute pulmonary edema panics and pulls off the CPAP mask as soon as it is strapped on. What is the best first approach?

    1. A. Tighten the straps so that he cannot remove it
    2. B. Raise the pressure so it works faster
    3. C. Abandon CPAP and intubate him at once
    4. D. Coach him and hold the mask on gently at first
    Show answer

    Answer: D. Coach him and hold the mask on gently at first

    Many patients feel smothered at first. Explain, hold the mask by hand, start at a low pressure, and strap it once he is breathing with it; small doses of an anxiolytic may be used per protocol. Forcing the mask on by tightening the straps worsens panic. Higher pressure at the start increases discomfort. An alert patient who may tolerate CPAP with coaching does not need immediate intubation.

19. A 2-year-old needs bag-mask ventilation. Which self-inflating bag is appropriate?

    1. A. A 250-mL neonatal bag to limit volume
    2. B. An adult bag squeezed with full force
    3. C. A pediatric bag of at least 450 mL
    4. D. A small bag with its pop-off taped shut
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    Answer: C. A pediatric bag of at least 450 mL

    AHA guidance is to use a self-inflating bag of at least 450 to 500 mL for infants and young children, giving just enough volume for chest rise. A 250-mL neonatal bag may not deliver an adequate breath for a toddler. An adult bag can be used with care, but squeezing it fully overinflates the lungs and stomach. A pop-off valve taped shut risks barotrauma unless pressure is needed and watched.

20. Why should a simple face mask run at about 6 L/min or more?

    1. A. Lower flows let the reservoir bag collapse
    2. B. Lower flows let exhaled CO2 build up in it
    3. C. Lower flows dry the airway more
    4. D. Lower flows wash out too much CO2
    Show answer

    Answer: B. Lower flows let exhaled CO2 build up in it

    A simple face mask has no valves, so a flow of at least about 5 to 6 L/min is needed to flush exhaled gas out of the mask; below that the patient rebreathes CO2. Low flow dries the airway less, not more. A simple mask has no reservoir bag; a collapsing bag is a nonrebreather problem. Low flow lets CO2 accumulate rather than washing too much of it out. A simple mask delivers roughly 35% to 60% oxygen.

21. A patient on CPAP for pulmonary edema becomes confused and then unresponsive with shallow breathing. What should you do?

    1. A. Switch to a nasal cannula
    2. B. Increase CPAP to 15 cmH2O
    3. C. Continue CPAP and reassess
    4. D. Remove CPAP and assist with BVM
    Show answer

    Answer: D. Remove CPAP and assist with BVM

    CPAP requires a patient who is breathing spontaneously and can protect the airway. Declining mental status calls for assisted ventilation.

22. A D cylinder reads 2,000 psi. Using a cylinder constant of 0.16 and a safe residual of 200 psi, how long will it last at 15 L/min?

    1. A. About 32 minutes
    2. B. About 19 minutes
    3. C. About 12 minutes
    4. D. About 21 minutes
    Show answer

    Answer: B. About 19 minutes

    (2,000 - 200) x 0.16 / 15 = 288 / 15, or about 19 minutes. Forgetting to subtract the safe residual gives about 21 minutes.

23. You must transport a patient for 40 minutes on a nonrebreather at 15 L/min. Your D cylinder reads 2,000 psi (constant 0.16, safe residual 200 psi). What should you do?

    1. A. Use the D cylinder; it lasts about 60 min
    2. B. Lower the flow to 10 L/min to stretch it
    3. C. Use it and switch to room air if it empties
    4. D. Bring a larger cylinder or a second D
    Show answer

    Answer: D. Bring a larger cylinder or a second D

    (2,000 - 200) x 0.16 / 15 = about 19 minutes, so one D cylinder cannot cover a 40-minute transport at 15 L/min. Bring an E cylinder (about 34 minutes at these settings), a second D, or plan to use the vehicle's main supply. The 60-minute estimate is a calculation error. Cutting the nonrebreather flow below 15 L/min lets the reservoir collapse. Planning to switch to room air when it empties is unsafe.

24. Why will an oxygen regulator not fit onto a nitrous oxide cylinder?

    1. A. The pin index positions differ by gas
    2. B. The cylinder threads are reversed
    3. C. Color-coded collars block the wrong regulator
    4. D. The cylinder neck is a larger size
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    Answer: A. The pin index positions differ by gas

    The pin index safety system places pins and holes in a different pattern for each gas, so an oxygen regulator cannot seat on a cylinder of another gas. Small medical cylinders use a yoke with pins, not reversed threads. Cylinder color is a visual cue that does not stop a regulator from seating, and small cylinders of different gases share the same post-valve size; the pin pattern is what differs.

25. Why must oil or petroleum products never be used on oxygen regulators or valves?

    1. A. They contaminate the oxygen
    2. B. They corrode the cylinder
    3. C. They can ignite under pressure
    4. D. They block the pin index
    Show answer

    Answer: C. They can ignite under pressure

    Oil and grease can spontaneously ignite in the presence of pressurized oxygen.

26. You bag an apneic adult with a pulse at 1 breath every 10 seconds with good chest rise. Over 10 minutes, EtCO2 climbs from 40 to 58 mmHg. What does this show?

    1. A. His cardiac output has fallen
    2. B. The mask seal has been lost
    3. C. The capnograph needs a calibration
    4. D. His minute ventilation is too low
    Show answer

    Answer: D. His minute ventilation is too low

    A rising EtCO2 with good chest rise means CO2 is being made faster than you are removing it: minute ventilation is too low. Increase to the adult rate of 1 breath every 6 seconds. Falling cardiac output lowers, not raises, EtCO2. A lost mask seal would remove the waveform and chest rise. A steady rise over 10 minutes is real, so there is no reason to think the capnograph needs calibration.

27. A 34-year-old on a nonrebreather after an overdose has an SpO2 of 92% but is breathing 6 times per minute with shallow breaths. What is the best action?

    1. A. Increase the oxygen to 25 L/min
    2. B. Switch to a nasal cannula
    3. C. Assist ventilations with a BVM
    4. D. Monitor; SpO2 is acceptable
    Show answer

    Answer: C. Assist ventilations with a BVM

    Oxygen alone does not fix hypoventilation. The patient needs assisted ventilations to restore adequate minute volume and clear CO2.

28. After ROSC, an intubated adult is being bagged at 24 breaths per minute, and his EtCO2 is 24 mmHg. What should you do?

    1. A. Keep this rate to lower his intracranial pressure
    2. B. Increase the rate to clear more CO2
    3. C. Slow the rate to bring EtCO2 toward 35-45
    4. D. Stop bagging until EtCO2 reaches 60
    Show answer

    Answer: C. Slow the rate to bring EtCO2 toward 35-45

    After ROSC, AHA advises normal ventilation (PaCO2 about 35 to 45 mmHg) and avoiding hyperventilation, which constricts cerebral vessels and lowers venous return. Slow to about 10 per minute and titrate to EtCO2. Routine hyperventilation to lower ICP is not recommended. Faster bagging worsens the problem. Stopping ventilation causes hypoxemia.

29. What is the main benefit of humidified oxygen during a long transport?

    1. A. Prevents drying of mucosa
    2. B. Lowers the risk of infection
    3. C. Raises the delivered FiO2
    4. D. Reduces oxygen consumption
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    Answer: A. Prevents drying of mucosa

    Dry oxygen irritates and dries the airway lining over time. Humidification improves comfort on longer transports.

30. What is a key advantage of an automatic transport ventilator over a BVM during a long transport?

    1. A. It cannot cause barotrauma
    2. B. It delivers a higher FiO2 than a BVM
    3. C. Consistent rate and volume
    4. D. It permits faster breath rates
    Show answer

    Answer: C. Consistent rate and volume

    An ATV delivers set rates and volumes reliably and frees a provider, but the patient still requires close monitoring. A BVM with a reservoir already delivers nearly 100% oxygen, so FiO2 is not the advantage, and faster rates are not a goal because they cause hyperventilation and air trapping. A ventilator can still cause barotrauma.

31. A child is frightened and refuses to keep an oxygen mask on her face. Which is the best option?

    1. A. A nonrebreather at 15 L/min
    2. B. Use a nasal cannula at 10 L/min
    3. C. Blow-by oxygen
    4. D. A simple mask at 2 L/min
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    Answer: C. Blow-by oxygen

    Blow-by oxygen held near the face by a caregiver avoids agitation, which increases oxygen demand and can worsen distress. A nonrebreather is still a mask she will fight, a simple mask at 2 L/min lets CO2 build up and is also a mask, and 10 L/min is above the usual cannula range and irritates the nose.