Nonshockable Rhythms: PEA, Asystole, Epinephrine, and Reversible Causes Practice Questions

25 multiple-choice questions on Nonshockable rhythms: PEA, asystole, epinephrine, and reversible causes for paramedic and EMT students, from Chapter 40 (Responding to the Field Code). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. In the PARAMEDIC2 trial of out-of-hospital cardiac arrest, epinephrine compared with placebo:

   1. A. Had no effect on ROSC or on survival
   2. B. Lowered survival, so it was later abandoned
   3. C. Raised survival, not clearly brain outcome
   4. D. Improved only the neurologic outcome
   Show answer

   Answer: C. Raised survival, not clearly brain outcome

   PARAMEDIC2 randomized about 8,000 patients and found higher 30-day survival with epinephrine (3.2% vs 2.4%), but the difference in survival with a favorable neurologic outcome (2.2% vs 1.9%) was not significant. Epinephrine also roughly tripled ROSC, so it clearly affects ROSC. It did not lower survival, and AHA continues to recommend it. The benefit was in survival overall, not a selective neurologic benefit; more survivors had severe disability in the epinephrine group. (Perkins 2018; AHA 2025 Part 9.)

2. A 30-year-old stung by several bees develops wheezing and swelling, then goes into PEA. Along with CPR and standard IV epinephrine, a key treatment is:

   1. A. IM epinephrine in place of IV dosing
   2. B. Diphenhydramine as the first drug
   3. C. Calcium chloride 1 g IV/IO push
   4. D. Rapid, large-volume IV fluid boluses
   Show answer

   Answer: D. Rapid, large-volume IV fluid boluses

   Anaphylactic arrest is driven by massive vasodilation and capillary leak, so aggressive crystalloid boluses are given along with CPR and standard arrest-dose IV or IO epinephrine, and the airway is secured early because of swelling. Once the patient is pulseless and IV or IO access is available, IM epinephrine is too slowly absorbed to replace IV dosing. Antihistamines are adjuncts that do not treat shock or arrest. Calcium has no role in anaphylaxis and is not given routinely in arrest. (AHA 2025 special circumstances and Part 9; ERC 2021 special circumstances.)

3. During compressions, your partner feels a femoral pulse with each compression. This finding:

   1. A. Does not show the heart is pumping
   2. B. Proves that ROSC has occurred
   3. C. Means that compressions can now stop
   4. D. Rules out PEA as the rhythm
   Show answer

   Answer: A. Does not show the heart is pumping

   A pulse felt at the femoral site during compressions may be generated by the compressions themselves and can even be venous rather than arterial, so it says nothing about whether the heart is beating on its own. ROSC is judged at a rhythm check, with an organized rhythm, a palpable pulse during the pause, or a sustained ETCO2 rise. Stopping compressions on this basis would leave the patient without flow. A compression-generated pulse can be felt in any rhythm, including PEA. (AHA 2010 to 2025 ALS guidance on pulse checks; ch40 nonshockable rhythms section.)

4. At a rhythm check, the monitor shows wide, slow complexes at 18 per minute, and no pulse is felt. This rhythm should be managed as:

   1. A. VF, with a shock at once
   2. B. PEA, with CPR and epinephrine
   3. C. Asystole, with pacing now
   4. D. A perfusing rhythm, so stop CPR
   Show answer

   Answer: B. PEA, with CPR and epinephrine

   Any organized electrical rhythm without a pulse, including a slow idioventricular or agonal rhythm, is PEA, so CPR continues, epinephrine is given every 3 to 5 minutes, and the team looks for reversible causes such as hyperkalemia or acidosis. VF is chaotic with no discrete complexes, so this rhythm is not shocked. It is not asystole, and pacing is not effective in arrest. Without a pulse, the rhythm is not perfusing anything, so CPR must continue. (AHA 2025 Part 9.)

5. For a patient in asystolic cardiac arrest, transcutaneous pacing:

   1. A. Is the first-line therapy for asystole
   2. B. Has not been shown to improve survival
   3. C. Should follow the first epinephrine dose
   4. D. Is indicated if pacer spikes are seen
   Show answer

   Answer: B. Has not been shown to improve survival

   Pacing in asystolic arrest does not improve ROSC or survival and is not recommended. Pacer spikes on the monitor do not mean the myocardium is capturing or producing a pulse.

6. Pulseless electrical activity is defined as:

   1. A. Organized rhythm without a pulse
   2. B. Chaotic electrical activity with no pulse
   3. C. A flat line confirmed in two leads
   4. D. A wide-complex rhythm with a weak pulse
   Show answer

   Answer: A. Organized rhythm without a pulse

   PEA is any organized rhythm, other than VF or pVT, that does not produce a palpable pulse. Chaotic activity is VF, and a rhythm with a pulse, however weak, is not cardiac arrest.

7. A 19-year-old with type 1 diabetes and a blood glucose too high to read goes into cardiac arrest. His blood pH was 6.85 shortly before. Among the Hs and Ts, this most directly reflects:

   1. A. Hypothermia
   2. B. Tension pneumothorax
   3. C. Tamponade
   4. D. Hydrogen ion
   Show answer

   Answer: D. Hydrogen ion

   Diabetic ketoacidosis this severe causes profound metabolic acidosis, the 'hydrogen ion' cause on the H list, along with dehydration and potassium shifts. Hypothermia is a low core temperature, which nothing here suggests. Dehydration contributes, but the pH of 6.85 points most directly to acid. Tension pneumothorax needs air trapped in the chest, usually from trauma or ventilation, and nothing suggests it. Tamponade is fluid in the pericardium preventing filling, which DKA does not cause. Treatment centers on high-quality CPR, ventilation, fluids, and the hospital correction of acidosis and potassium. (AHA 2025 Part 9 reversible causes.)

8. A woman in PEA after a fall has an obviously fractured right tibia, and IV attempts have failed. For IO access you should:

   1. A. Place it just below the fracture site
   2. B. Use the right tibia; it does not matter
   3. C. Use another bone, such as the humerus
   4. D. Give the drugs by ET tube instead
   Show answer

   Answer: C. Use another bone, such as the humerus

   A fracture in the target bone is a contraindication to IO insertion, because fluid and drugs can leak out of the break into the tissues; choose another site such as the proximal humerus or the opposite tibia. Placing the needle below the fracture in the same bone has the same leak problem. The fracture does matter for that bone. Drugs given by ET tube reach unreliable blood levels, and another IO site is readily available. (Manufacturer IO instructions; 2025 AHA Part 9.)

9. During CPR, the forearm IV site swells each time a drug is pushed. You should:

   1. A. Push the next drug faster through it
   2. B. Give the next doses at double strength
   3. C. Stop using it and get IV or IO access
   4. D. Raise the arm and keep using the line
   Show answer

   Answer: C. Stop using it and get IV or IO access

   Swelling with each push means the line has infiltrated, so drugs are going into the tissue rather than the circulation; stop using it and obtain new IV or IO access. Pushing faster forces more drug into the tissue. Doubling doses is unsafe, because the drug may reach the circulation later, and it does not fix the access problem. Raising the arm helps a working IV but cannot make an infiltrated line deliver drugs to the heart. (2025 AHA Part 9 vascular access.)

10. A 72-year-old man with COPD who has been intubated for 20 minutes, with the tube still at 23 cm at the teeth, becomes hard to bag and then goes into PEA. Breath sounds are absent on the left. You should:

    1. A. Needle-decompress the left chest
    2. B. Give 1 mg of epinephrine and wait
    3. C. Pull the tube back 3 cm and re-bag
    4. D. Increase the ventilation rate
    Show answer

    Answer: A. Needle-decompress the left chest

    Rising airway resistance, absent breath sounds on one side, and PEA in a ventilated COPD patient point to tension pneumothorax, which needle decompression treats. Epinephrine cannot overcome an obstructive cause. A right mainstem tube can also silence the left chest, but it does not usually cause PEA, and the depth here has not changed since placement. Faster ventilation adds more air to the pleural space and worsens the tension. (2025 AHA Part 9 reversible causes.)

11. A 58-year-old man with a history of bleeding ulcers vomits large amounts of blood and then goes into PEA. The reversible cause to address is:

    1. A. Hypothermia
    2. B. Hyperkalemia
    3. C. Coronary thrombosis
    4. D. Hypovolemia
    Show answer

    Answer: D. Hypovolemia

    Massive GI bleeding causes hemorrhagic hypovolemia, and these patients need volume replacement, ideally blood, along with CPR. Epinephrine cannot raise blood pressure if there is no circulating volume.

12. Two weeks after hip surgery, a 67-year-old woman suddenly becomes short of breath, collapses, and is found in PEA. The most likely cause is:

    1. A. Acute intracerebral hemorrhage
    2. B. Massive pulmonary embolism
    3. C. Severe hypoglycemia
    4. D. Tension pneumothorax
    Show answer

    Answer: B. Massive pulmonary embolism

    Recent surgery and immobility are major risk factors for venous thromboembolism, and sudden dyspnea followed by collapse in PEA is typical of massive PE. Fibrinolysis may be considered for suspected PE in arrest, usually at the hospital.

13. A 6-year-old who choked on a grape is found in PEA after the obstruction is cleared. The reversible cause most important to correct is:

    1. A. Hyperkalemia
    2. B. Hypothermia
    3. C. Cardiac tamponade
    4. D. Hypoxia
    Show answer

    Answer: D. Hypoxia

    Asphyxial arrest results from hypoxia, so effective oxygenation and ventilation are central to resuscitation. Correcting oxygenation often restores a pulse faster than drugs alone.

14. During a pause for a rhythm check, a patient in PEA has a narrow rhythm at 90 per minute and no palpable pulse, but the ETCO2 stays near 35 mmHg. This most suggests:

    1. A. An esophageal tube placement
    2. B. Hyperventilation by the person bagging
    3. C. Weak output too low to feel
    4. D. Fine VF hidden in this lead
    Show answer

    Answer: C. Weak output too low to feel

    ETCO2 depends on blood flow through the lungs, so a value near normal that persists while compressions are paused means the heart itself is still moving some blood, even though no pulse can be felt; this is sometimes called pseudo-PEA, and the team should recheck for a pulse, look for the cause, and follow protocol. An esophageal tube produces little or no CO2 waveform. Hyperventilation lowers ETCO2 rather than keeping it high. Fine VF does not produce an organized narrow rhythm, and it generates no flow. (2025 AHA Part 9 on ETCO2 as a physiologic measure of flow.)

15. In PEA, a narrow-complex, rapid rhythm most suggests:

    1. A. A mechanical cause like tamponade
    2. B. Severe hyperkalemia as the main cause
    3. C. Sodium channel blocker toxicity
    4. D. End-stage myocardial death
    Show answer

    Answer: A. A mechanical cause like tamponade

    A narrow, fast PEA usually means the conduction system is intact but the heart cannot fill or eject, as in tamponade, tension pneumothorax, hypovolemia, or PE. Wide, slow PEA points more to metabolic or toxic causes such as hyperkalemia.

16. A 24-year-old man with a stab wound just left of the sternum is in PEA with distended neck veins. The most likely cause is:

    1. A. Hypovolemic shock alone
    2. B. Pericardial tamponade
    3. C. Commotio cordis
    4. D. Hyperkalemia
    Show answer

    Answer: B. Pericardial tamponade

    A precordial stab wound with JVD and PEA strongly suggests tamponade; the treatment is pericardial decompression, so rapid transport to a trauma center is critical. Pure hypovolemia would produce flat, not distended, neck veins.

17. Your partner suggests calcium chloride for a 60-year-old in asystole with no known hyperkalemia, overdose, or low calcium. Under 2025 AHA guidance, routine calcium in cardiac arrest is:

    1. A. Recommended after two epinephrine doses
    2. B. Recommended for all nonshockable arrests
    3. C. Required before atropine in asystole
    4. D. Not recommended
    Show answer

    Answer: D. Not recommended

    The 2025 AHA adult ALS guidelines state that routine calcium is not recommended in cardiac arrest (Class 3: No Benefit), because trials showed no benefit and a possible harm signal; calcium is reserved for specific causes such as hyperkalemia, calcium channel blocker overdose, or hypocalcemia. It is not tied to a number of epinephrine doses. It is not recommended for nonshockable arrests in general. Atropine is no longer part of the arrest algorithm at all. (2025 AHA Part 9.)

18. During a PEA arrest, the best time for the team to work through the Hs and Ts is:

    1. A. During the pulse check pause
    2. B. Only after ROSC has been achieved
    3. C. During each 2-minute CPR cycle
    4. D. Before compressions are started
    Show answer

    Answer: C. During each 2-minute CPR cycle

    The search for reversible causes should go on while compressions continue, with the leader or a designated member reviewing the history, findings, and ETCO2 during each cycle, so treatment can start without adding pauses. The pulse check pause must stay under 10 seconds and cannot be extended for a discussion. Waiting for ROSC defeats the purpose, since many patients in PEA will not regain a pulse until the cause is treated. Compressions should never wait for a diagnosis. (AHA 2025 Part 9.)

19. With 2-minute CPR cycles, giving epinephrine every 3 to 5 minutes usually means giving it:

    1. A. At every other rhythm check
    2. B. At every rhythm check
    3. C. At every third rhythm check
    4. D. Once, with no repeat dose
    Show answer

    Answer: A. At every other rhythm check

    Two 2-minute cycles span 4 minutes, which falls within the 3- to 5-minute interval, so many teams give epinephrine at alternating rhythm checks. Dosing at every check would give it every 2 minutes, more often than recommended.

20. Compared with the proximal tibia, an advantage of the proximal humerus for IO access in an adult in cardiac arrest is:

    1. A. No need for a flush before use
    2. B. Faster drug delivery to the heart
    3. C. No risk of infection at the insertion site
    4. D. Use of a much smaller needle
    Show answer

    Answer: B. Faster drug delivery to the heart

    The proximal humerus drains through the axillary and subclavian veins directly toward the heart, so flow rates are higher and drugs reach the central circulation faster than from the tibia, although recent trials have not shown that the IO site or route changes survival. Every IO line still needs a flush to open the marrow space. Infection is uncommon at any IO site but is never zero. Adult humeral access typically uses a longer needle, not a smaller one, because of the overlying tissue. (Manufacturer IO instructions; PARAMEDIC-3 and IVIO 2025; 2025 AHA Part 9.)

21. Under 2025 AHA guidance, giving epinephrine down an endotracheal tube during adult cardiac arrest is:

    1. A. No longer in the guidelines
    2. B. Preferred over the IO route
    3. C. Given at the same dose as IV
    4. D. Required before IV is tried
    Show answer

    Answer: A. No longer in the guidelines

    The 2025 AHA adult ALS guidelines removed the endotracheal route, because drugs given through a secured tube produce low and unpredictable blood levels; IV access is tried first and IO is used if IV fails or is not feasible. The ET route was never preferred over IO. Older guidance used 2 to 2.5 times the IV dose by ET tube, not the same dose, and some local protocols still list it as a last resort, so know your protocol. Nothing requires ET dosing before IV access is attempted. (2025 AHA Part 9.)

22. A 34-year-old man in a severe asthma attack goes into PEA. Bagging is very hard, and his chest stays hyperinflated. You should:

    1. A. Raise the ventilation rate to 20 per minute
    2. B. Give a larger tidal volume to open airways
    3. C. Briefly disconnect the bag to vent air
    4. D. Add 10 cm H2O of PEEP to the bag
    Show answer

    Answer: C. Briefly disconnect the bag to vent air

    Air trapping (auto-PEEP) in severe asthma raises intrathoracic pressure and can cause PEA; a brief disconnection with chest pressure lets trapped air out and restores venous return. Faster ventilation and larger breaths both worsen air trapping, and adding PEEP raises intrathoracic pressure further.

23. Of the initial cardiac arrest rhythms, the lowest survival to discharge is seen with:

    1. A. Pulseless VT
    2. B. VF
    3. C. PEA
    4. D. Asystole
    Show answer

    Answer: D. Asystole

    Asystole often reflects a prolonged, unwitnessed arrest with severe ischemia, and survival is usually below 2%. PEA does somewhat better because it may have a treatable cause.

24. At a rhythm check during CPR, an organized rhythm at 70 per minute appears. You should:

    1. A. Resume CPR without checking for any pulse
    2. B. Check for a pulse for up to 10 seconds
    3. C. Check a pulse for a full 30 seconds
    4. D. Start pacing before checking a pulse
    Show answer

    Answer: B. Check for a pulse for up to 10 seconds

    When an organized rhythm appears at a scheduled rhythm check, a brief pulse check decides between post-ROSC care and continuing CPR for PEA. A 30-second check is far longer than the 10-second limit and leaves the patient without flow, and pacing has no role until you know whether there is a pulse. This differs from the moment just after a shock, when CPR resumes immediately.

25. After you give epinephrine through a hand IV during CPR, you should:

    1. A. Flush with saline and raise the arm
    2. B. Wait 2 minutes before flushing the line
    3. C. Lower the arm well below the heart
    4. D. Massage the IV site for a minute
    Show answer

    Answer: A. Flush with saline and raise the arm

    Drugs given through a peripheral vein during CPR reach the central circulation slowly. A 20 mL saline flush and briefly elevating the extremity speed delivery. Lowering the arm or delaying the flush slows drug arrival, and massage does not help.