10 free AEMT practice questions: Waveform Capnography and Ventilation Monitoring

Hyperventilation: gets picked because the respiratory rate of 26 is elevated, but hyperventilation lowers the ETCO2 number while the waveform stays rectangular with a normal plateau. The tracing here is defined by its curved shape, not its height, so the rate alone doesn't explain it.

A disconnected sampling line: a real event, but it drops the tracing to a flat zero line with no waveform at all. This patient's capnogram is still producing a full rising curve on every breath, so the line is intact.

Falling cardiac output: does drop the ETCO2 number as less CO2 returns to the lungs, but the square waveform shape stays preserved, just shorter. Nothing about reduced blood flow curves the upstroke the way narrowed airways do.

How much oxygen is bound to hemoglobin: This is what the pulse oximeter already reports, the fraction of hemoglobin carrying oxygen, and the question already gives you that number as 97%. It restates information you have instead of naming what the capnography value adds on top of it.

Whether the airway is anatomically open: The rectangular waveform does confirm gas is moving through a patent airway, which is a real use of the tracing, but the number 58 mmHg and the rate of 8 point to a ventilation and CO2 clearance problem, not a question about whether the airway is open.

How much oxygen is dissolved in the plasma: Dissolved plasma oxygen is measured as PaO2 on a blood gas, and neither the pulse oximeter nor the capnometer reports it, so it has no bearing on interpreting this patient's numbers.

It shows the patient needs a higher oxygen concentration: The saturation is 94%, and more oxygen does not address why the carbon dioxide is low. The number is pointing at the circulation and the acid load rather than at oxygenation.

It confirms the patient has a lower airway obstruction: An obstruction in the lower airways curves the upstroke into a shark fin. This waveform is rectangular and the lungs are clear, so the shape is telling you the airways are open.

It indicates the sampling cannula is poorly positioned: A poorly positioned cannula degrades the tracing rather than producing a clean rectangular waveform at a consistently low value.

Continue at the current rate and reassess in five minutes: Normal vitals, BP 132/80, pulse 98, SpO2 98 percent, make continuing at the same rate look safe, but the end-tidal carbon dioxide of 27 mmHg with a rectangular waveform shows you are already overventilating, and waiting five minutes just lets that correctable rate keep driving the number down.

Increase the volume delivered with each breath: Increasing volume looks like a fix when oxygenation or ventilation seems inadequate. Here the waveform shape is normal and the SpO2 is 98 percent, so volume is not the problem; adding volume on top of a 16 breath per minute rate would only lower the carbon dioxide further and raise intrathoracic pressure more.

Slow to one breath every 10 seconds: One breath every 10 seconds calculates out to 6 breaths per minute, which undershoots the adult target of 10. Correcting the current rate of 16 by swinging past 10 down to 6 replaces one wrong rate with another wrong rate instead of the correct one.

Visible symmetrical rise of the chest wall: This is a genuine supporting finding and you do look for it, but chest rise can be produced by air going into the stomach, so it does not confirm placement on its own.

Breath sounds heard bilaterally at the axillae: Listening at the axillae belongs in your check and it is on the supporting list, but it is not the finding the guide names as primary.

A pulse oximetry reading that begins climbing: A climbing saturation is reassuring and it is on the supporting list, but it lags by a minute or more and it tells you about oxygen rather than about where the device is sitting.

The sampling line needs to be repositioned: This would be right if the tracing were irregular, dampened, or missing a plateau, signs the cannula or sampling line has kinked or slipped. Here the waveform is clean, rectangular, with a flat plateau, exactly what a correctly seated line should produce.

The patient is hypoventilating: This reads the number instead of the shape: hypoventilation shows up as a rising ETCO2, typically above 45 mmHg, paired with a widening waveform. This patient's ETCO2 sits at 41 mmHg, inside the 35 to 45 mmHg normal range, and the respiratory rate of 30 points to tachypnea, not hypoventilation. The question is asking what the shape tells you, not what the number tells you, and those are two separate readings off the same capnogram.

Blood flow to the lungs has dropped: A sudden drop in pulmonary blood flow, from a pulmonary embolism or cardiac arrest, shows up as an abrupt fall in the ETCO2 value with the waveform losing height, not as a change in the plateau's slope. This patient's ETCO2 is normal at 41 mmHg and the blood pressure of 186/104 shows no drop in perfusion.

The patient is beginning to hypoventilate: Hypoventilation shows up as a rising EtCO2 number on an otherwise unchanged waveform shape, not a shark fin squaring off. Here the respiratory rate is 22 and the described change is in slope and plateau shape, not a rising value, so this answers a different question than the one the capnogram is showing.

The sampling line has been repositioned: A kinked or displaced sampling line typically distorts, flattens, or loses the tracing altogether, it does not selectively steepen the upstroke and square the plateau. The change tracks the timing of the nebulized bronchodilator, which points to airway physiology, not equipment.

Blood flow to the lungs has improved: Improved pulmonary blood flow raises the height of the plateau, the EtCO2 value itself, the way it does after ROSC in cardiac arrest, rather than changing the slope of the upstroke. This tracing describes a shape change from shark fin toward square, an airway finding, not a perfusion one.

Oxygen uptake, circulation, and ventilation: Oxygen uptake belongs to the pulse oximeter. Capnography is a carbon dioxide measurement from beginning to end.

Carbon dioxide production, airway diameter, and ventilation: Airway diameter shows up in the shape of the waveform rather than in the value, and leaving the circulation out drops the process that makes this a perfusion monitor.

Oxygen uptake, carbon dioxide production, and airway diameter: Two of these three are wrong for the same reasons, since oxygen uptake is not measured here and airway diameter changes the shape rather than the number.

Interpretation is permitted only after a physician is contacted by radio: This describes skills gated behind online medical control, but capnography interpretation is written into AEMT scope itself, not behind a radio call. Nothing in the question ties this to contacting a physician; the rule breaks because it turns an independent scope skill into a permission-based one.

Monitoring is within scope, while interpretation requires paramedic authorization: 12-lead ECG interpretation really is split that way, with acquisition inside EMS scope while full interpretation is reserved upward. Capnography doesn't follow that pattern, monitoring and interpreting the waveform are both explicitly AEMT skills, so this splits a rule that belongs to a different tool.

Interpretation is permitted only for patients with an advanced airway: Capnography interpretation isn't limited to intubated patients; a nasal sampling cannula reads end-tidal CO2 on a patient breathing on their own, useful for monitoring sedation or opioid overdose. The question never mentions an advanced airway, so restricting interpretation to that setting narrows a skill that applies more broadly.

The concentration of oxygen being delivered: Turning FiO2 up or down changes the SpO2 reading on pulse oximetry, since that measures oxygen saturation, not carbon dioxide. Capnography reads exhaled CO2, and oxygen delivery does nothing to how much CO2 the lungs clear, so it answers a different measurement than the one the question asks about.

The patient's body temperature: Fever and hypermetabolic states, like malignant hyperthermia or thyroid storm, do raise CO2 production and can push ETCO2 up over minutes, but the question asks what moves the number most directly, and temperature shifts CO2 production slowly next to what a bag rate change does within a few breaths, so ventilation stays the dominant lever.

The position the patient is transported in: Positioning, like sitting a patient upright versus supine, can affect lung volumes and how easily the chest expands, which does change how well someone ventilates, but it is not what you adjust to correct an abnormal ETCO2 reading in the moment; rate and depth are the direct controls, position is a background factor.