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Free NREMT practice questionsFree AEMT practice questions · Airway, Respiration & Ventilation

10 free AEMT practice questions: Waveform Capnography and Ventilation Monitoring

These are real questions from the same bank the app draws from. Each one is written to the NREMT AEMT content specifications and kept inside the AEMT scope of practice. Pick an answer and you get the full rationale, including why the other three options are wrong.

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Question 1 of 10

A 23-year-old patient with a history of asthma is short of breath with audible wheezing. The capnography tracing rises in a slow curved slope that never truly flattens. The vital signs are BP 128/76, P 112, R 26, and SpO₂ 93% on room air. What does that waveform shape indicate?

Show the answer and rationale

Correct answer · Bronchospasm

This waveform shows bronchospasm. The tracing rises in a slow curved slope that never flattens into a plateau. That shape is called a shark fin. Bronchospasm narrows the lower airways unevenly. The alveoli behind the tightest airways empty late, out of step with the rest of the lung. Carbon dioxide keeps rising through the whole exhalation instead of leveling off. This patient also has asthma and audible wheezing. Keep treating with bronchodilators. As the airways open back up, you will see the waveform square off.

Why the others are wrong

Hyperventilation: would fit the fast respiratory rate of 26. Hyperventilation lowers the ETCO2 number, and the waveform stays rectangular with a normal plateau. This tracing is curved. The fast rate alone does not explain a curved shape.

A disconnected sampling line: drops the tracing to a flat line at zero with no waveform. This patient's capnogram still shows a full rising curve on every breath. The sampling line is still connected.

Falling cardiac output: does drop the ETCO2 number, because less CO2 gets back to the lungs. The square shape of the waveform stays the same and just gets shorter. Less blood flow does not curve the upstroke the way narrowed airways do.

Question 2 of 10

A 33-year-old patient who took an unknown quantity of a sedative is drowsy and breathing shallowly. The pulse oximeter reads 97% on an NRB while the end-tidal carbon dioxide reads 58 mmHg with a rectangular waveform. The vital signs are BP 112/68, P 64, R 8, and SpO₂ 97% on an NRB. What does the capnography reading add to the assessment?

Show the answer and rationale

Correct answer · How well carbon dioxide is being cleared

Capnography tells you how well carbon dioxide is being cleared. This patient took a sedative, the respiratory rate is 8, and the end-tidal reading is 58 mmHg. A number that high means the patient is hypoventilating and holding onto CO2. The NRB is keeping the hemoglobin fully loaded with oxygen, so the SpO₂ still reads 97%. Pulse oximetry cannot show you the CO2 building up. Start assisting ventilations with a bag-valve mask now. Do not wait for the SpO₂ to drop. Without help, the overdose can move on to respiratory failure and acidosis.

Why the others are wrong

How much oxygen is bound to hemoglobin: what the pulse oximeter measures. The question already gives you that number, 97%. Capnography adds something the pulse oximeter cannot.

Whether the airway is anatomically open: The rectangular waveform does show gas moving through an open airway. A reading of 58 with a rate of 8 tells you about ventilation. This patient is not clearing CO2, and the airway being open does not fix that.

How much oxygen is dissolved in the plasma: Oxygen dissolved in the plasma is the PaO2 on a blood gas. Neither the pulse oximeter nor the capnometer measures PaO2. Dissolved oxygen has nothing to do with reading this patient's numbers.

Question 3 of 10

A 46-year-old patient with a productive cough and a fever is breathing rapidly with clear lungs. The end-tidal carbon dioxide reads 21 mmHg with a rectangular waveform. The vital signs are BP 116/70, P 114, R 28, and SpO₂ 94% on room air. What does the low reading add to the assessment?

Show the answer and rationale

Correct answer · It supports sepsis before the blood pressure drops

The low reading supports sepsis before the blood pressure drops. This patient has a productive cough, a fever, a pulse of 114, and a respiratory rate of 28. The end-tidal carbon dioxide is 21. An end-tidal reading under about 25 in a patient with an infection goes along with metabolic acidosis and worse outcomes. The blood pressure is still 116/70. The low end-tidal number gives you an early, objective sign that backs up your sepsis impression. If you wait for a pressure of 80 before you treat this patient as sick, you are finding the sepsis late.

Why the others are wrong

It shows the patient needs a higher oxygen concentration: More oxygen is for a patient with a low saturation. This saturation is 94%, and more oxygen does nothing about why the carbon dioxide is low. The low number is pointing at circulation and acid buildup, not oxygenation.

It confirms the patient has a lower airway obstruction: A lower airway obstruction bends the upstroke into a shark fin. This waveform is rectangular and the lungs are clear. Both of those tell you the airways are open.

It indicates the sampling cannula is poorly positioned: A poorly placed cannula gives you a messy, damaged tracing. This tracing is a clean rectangle that reads low every time.

Question 4 of 10

A 43-year-old patient in respiratory failure is being ventilated with a BVM. The rate display reads 16 breaths per minute and the end-tidal carbon dioxide has fallen to 27 mmHg with a rectangular waveform. The vital signs are BP 132/80, P 98, R 16, and SpO₂ 98% on high-flow oxygen. What adjustment should be made?

Show the answer and rationale

Correct answer · Slow to one breath every 6 seconds

You are ventilating too fast, and you need to slow to one breath every 6 seconds. The rate display reads 16. The end-tidal carbon dioxide is 27 with a rectangular waveform. Normal end-tidal carbon dioxide is 35 to 45, so 27 is well below normal. A normal square waveform with a low number means the lungs are fine. You are blowing off carbon dioxide faster than the body makes it. Each positive pressure breath also raises the pressure inside the chest. Breaths this close together keep the chest pressure up, so less blood returns to the heart and cardiac output drops. An adult with a pulse gets ten breaths per minute, which is one breath every 6 seconds. Slow to that rate so the carbon dioxide comes back up to normal and the pressure in the chest comes down.

Why the others are wrong

Continue at the current rate and reassess in five minutes: Continuing is fine when the ventilation rate is already right. The blood pressure of 132/80, pulse of 98, and SpO₂ of 98% are all normal. The end-tidal reading of 27 with a rectangular waveform says you are already overventilating. Waiting five minutes just lets a fixable rate keep pushing the number lower.

Increase the volume delivered with each breath: More volume helps when the patient is not moving enough air. Here the waveform is normal and the SpO₂ is 98%. Volume is not the problem. More volume on top of a rate of 16 lowers the carbon dioxide further and raises the pressure in the chest even more.

Slow to one breath every 10 seconds: One breath every 10 seconds works out to 6 breaths per minute. The adult target is 10 breaths per minute. Going from 16 down to 6 trades one wrong rate for another wrong rate.

Question 5 of 10

A 51-year-old patient in respiratory failure has a supraglottic airway placed. The vital signs are BP 138/84, P 104, R 10, and SpO₂ 94% on high-flow oxygen. Which finding is the primary confirmation that the device is correctly seated?

Show the answer and rationale

Correct answer · A normal square waveform with every delivered breath

Continuous waveform capnography is the primary confirmation that a supraglottic airway is seated right. A device that is seated correctly gives you a normal square waveform with every breath you deliver. No other finding gives you that proof breath by breath. You should still check chest rise, breath sounds, and the pulse oximeter. Those are supporting findings. They back up what the waveform already told you. If the waveform and your other findings disagree, trust the waveform.

Why the others are wrong

Visible symmetrical rise of the chest wall: Symmetrical chest rise is a real supporting finding, and you do look for it. Air going into the stomach can also make the chest rise. Chest rise alone does not confirm where the device is.

Breath sounds heard bilaterally at the axillae: Breath sounds at the axillae belong in your check as a supporting finding. Listening only tells you about the moment you listened. The waveform confirms placement on every delivered breath.

A pulse oximetry reading that begins climbing: A climbing saturation is reassuring, and it is a supporting finding too. The saturation lags behind by a minute or more. A pulse oximeter tells you about oxygen, and it says nothing about where the device is sitting.

Question 6 of 10

An 85-year-old patient is short of breath at night with wet-sounding lungs and pink frothy sputum at the lips. The capnogram shows a rectangular waveform with a flat plateau and an end-tidal carbon dioxide of 41 mmHg. The vital signs are BP 186/104, P 108, R 30, and SpO₂ 88% on room air. What does the waveform shape indicate?

Show the answer and rationale

Correct answer · The lower airways are not constricted

The waveform shape tells you the lower airways are not constricted. The capnogram is rectangular with a flat plateau. When the lower airways are open, the alveoli empty together. The upstroke rises nearly straight up and levels into a flat plateau. Bronchospasm makes the alveoli empty unevenly. Alveoli behind narrowed airways release their gas late, and the tracing slopes into a shark fin. This patient is short of breath at night with wet lungs and pink frothy sputum. Those findings point to pulmonary edema, which is fluid backing up into the alveoli from left heart failure. CPAP is the most effective field treatment, because CPAP pushes fluid back out of the alveoli. A bronchodilator opens constricted airways, and these airways are not constricted.

Why the others are wrong

The sampling line needs to be repositioned: Repositioning the sampling line is right when the waveform drops out or loses its shape because of the line. This capnogram is a clean rectangle with a flat plateau. A rectangle is the normal shape, so the line is reading correctly.

The patient is hypoventilating: Hypoventilation shows up in the number. The end-tidal reading climbs above 45 while the shape stays normal. This patient's end-tidal reading is 41, inside the normal range of 35 to 45. The respiratory rate of 30 is fast, not slow. Hypoventilation also does not change the shape, and the question asks about the shape.

Blood flow to the lungs has dropped: Blood flow to the lungs drops with a pulmonary embolism or cardiac arrest. Less blood reaching the lungs drives the end-tidal number down while the shape stays the same. This patient's end-tidal reading is a normal 41, and the blood pressure of 186/104 shows no drop in perfusion.

Question 7 of 10

A 17-year-old patient with an asthma flare had a steeply upsloping capnogram on arrival. After a nebulized bronchodilator the upstroke has steepened and the plateau has flattened toward a square shape. The vital signs are BP 120/74, P 104, R 22, and SpO₂ 96% on high-flow oxygen. What does this change indicate?

Show the answer and rationale

Correct answer · The airways are opening and the treatment worked

The airways are opening, and the bronchodilator worked. On arrival this patient had a shark fin capnogram. After the nebulizer, the upstroke got steeper and the plateau flattened toward a square shape. A shark fin forms because bronchoconstriction makes the alveoli empty unevenly and late. The CO2 reaches the sensor in a staggered wave instead of all together. The bronchodilator relaxes the smooth muscle in the airways. Once the alveoli empty together again, the upstroke straightens and the plateau squares off. This waveform change is objective proof the obstruction is clearing, even before the patient says they feel better. You know the treatment is working, so reassess instead of repeating it blindly.

Why the others are wrong

The patient is beginning to hypoventilate: Hypoventilation shows up as a rising EtCO2 number on a waveform with the same shape. Here the rate is 22, and what changed is the slope and the plateau. Nothing in the question says the number went up.

The sampling line has been repositioned: A kinked or moved sampling line usually distorts, flattens, or loses the tracing altogether. A problem with the line does not steepen the upstroke and square off the plateau. The change came right after the nebulized bronchodilator, which points to the airways.

Blood flow to the lungs has improved: Better blood flow to the lungs raises the height of the plateau, which is the EtCO2 value itself. You see that after ROSC in cardiac arrest. More blood flow does not change the slope of the upstroke. This tracing changed shape, from a shark fin toward a square, and a shape change like that is an airway finding.

Question 8 of 10

The end-tidal carbon dioxide value on a waveform capnography display reflects three processes at once. Which set of three is correct?

Show the answer and rationale

Correct answer · Carbon dioxide production, circulation, and ventilation

End-tidal carbon dioxide depends on carbon dioxide production, circulation, and ventilation. First, the body has to make carbon dioxide. Then the circulation has to carry that carbon dioxide to the lungs. Last, ventilation has to move the carbon dioxide out. When the number is abnormal, ask which of the three changed. The rest of your assessment usually tells you which one it was.

Why the others are wrong

Oxygen uptake, circulation, and ventilation: Oxygen uptake is what the pulse oximeter measures. Capnography only measures carbon dioxide. Circulation and ventilation belong on the list, and oxygen uptake does not.

Carbon dioxide production, airway diameter, and ventilation: Airway diameter changes the shape of the waveform, not the number. This set also leaves out circulation. Circulation is what lets capnography tell you about perfusion.

Oxygen uptake, carbon dioxide production, and airway diameter: This set has both wrong pieces. The pulse oximeter measures oxygen uptake, and airway diameter changes the waveform shape instead of the number. Carbon dioxide production is the only part of this set that belongs.

Question 9 of 10

Waveform capnography is one of the additions that distinguishes the AEMT level from the EMT level. Which statement describes the AEMT scope correctly?

Show the answer and rationale

Correct answer · Both monitoring and interpreting the waveform are within AEMT scope

Monitoring and interpreting waveform capnography are both in AEMT scope. The AEMT curriculum treats reading the waveform as part of the skill, not just placing the sensor. The shape of the waveform shows you things the number cannot. The waveform shows the upstroke, the plateau, and the baseline of every breath. Those changes can show you bronchospasm, hyperventilation, or a sudden drop from a tube that came out or a patient who arrested. You are allowed to read the waveform yourself, so you act on what you see. Adjust the ventilation rate or fix the airway right away. You do not wait for someone else to read the waveform.

Why the others are wrong

Interpretation is permitted only after a physician is contacted by radio: Some skills do require a call to online medical control first. Capnography interpretation is not one of them. Reading the waveform is written into AEMT scope, and nothing in the question ties capnography to a physician on the radio.

Monitoring is within scope, while interpretation requires paramedic authorization: Splitting monitoring from interpretation is how the 12-lead ECG works. Getting the tracing is in EMS scope, and full interpretation belongs to a higher level. Capnography does not split that way. Monitoring and interpreting the waveform are both AEMT skills.

Interpretation is permitted only for patients with an advanced airway: Capnography works on intubated patients, and it is not limited to them. A nasal sampling cannula reads end-tidal carbon dioxide on a patient who is breathing on their own. A nasal cannula setup is useful for watching a sedated patient or an opioid overdose.

Question 10 of 10

In a patient with a pulse, which factor moves the end-tidal carbon dioxide value most directly?

Show the answer and rationale

Correct answer · How fast and how deeply the patient is ventilated

How fast and how deeply the patient is ventilated moves the end-tidal number most directly. Rate and tidal volume set the minute ventilation. Minute ventilation is what clears carbon dioxide out of the alveoli with each breath. The ETCO2 moves opposite to ventilation. Hypoventilate and CO2 backs up, so the number goes up. Hyperventilate and CO2 blows off, so the number goes down. You control ventilation breath to breath with the bag. When the number drifts, adjust the rate and depth instead of the oxygen flow or the patient's position. You also use that same trend to confirm tube placement and catch apnea in real time.

Why the others are wrong

The concentration of oxygen being delivered: Turning the oxygen up or down changes the SpO₂, because pulse oximetry measures oxygen saturation. Capnography reads exhaled CO2. The oxygen you deliver does nothing to how much CO2 the lungs clear.

The patient's body temperature: Fever and high metabolism states, like malignant hyperthermia or thyroid storm, do make more CO2. They can push the ETCO2 up over minutes. The question asks what moves the number most directly. A change in the bag rate moves the number within a few breaths, so ventilation is still the main control.

The position the patient is transported in: Position does make some difference. Sitting a patient upright instead of lying flat changes lung volumes and how easily the chest expands. Position is still not what you adjust to fix an abnormal ETCO2 in the moment. Rate and depth are the direct controls.

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