20 free CEN practice questions

Correct answer: A · Sublingual nitroglycerin for chest pain

Inferior ST elevation with hypotension, clear lungs, distended neck veins, and ST elevation in V4R indicates right ventricular infarction. The right ventricle depends on preload, so nitrates can cause profound hypotension. The 2025 ACC/AHA acute coronary syndromes guideline lists hypotension and right ventricular infarction among the reasons nitrates may not be appropriate, and an ACC review of RV infarction advises right-sided leads for all inferior MIs, avoiding IV nitroglycerin, and optimizing RV preload. A cautious saline bolus supports that preload, aspirin is standard early therapy, and prompt reperfusion in the catheterization lab is the definitive treatment, so those orders are appropriate.

Look for this next time: In inferior STEMI, check right-sided leads; with RV infarction or hypotension, question nitrates and support preload.

Correct answer: B · An IV beta-blocker, such as esmolol or labetalol

The 2022 ACC/AHA aortic disease guideline recommends IV beta-blockers as the initial management of acute aortic syndromes unless contraindicated, aiming for a systolic pressure below 120 mm Hg (or the lowest pressure that maintains end-organ perfusion) and a heart rate of 60 to 80 beats per minute, and adds vasodilators only if blood pressure is not controlled. Lowering heart rate and contractility first reduces the shear force on the aortic wall. A vasodilator such as nitroprusside given alone can cause reflex tachycardia and increase that force. Anticoagulants and thrombolytics can cause catastrophic bleeding into the false lumen or the pericardium and are dangerous in dissection.

Look for this next time: In acute aortic dissection, give an IV beta-blocker first, then add a vasodilator only if blood pressure stays high.

Correct answer: A · A corticosteroid such as dexamethasone, plus nebulized epinephrine

A barking cough, hoarseness, and stridor after a cold in a 2-year-old fit croup, and stridor at rest with retractions means at least moderate severity. A Clinical Evidence review published in American Family Physician in 2016 found that oral or IM dexamethasone and nebulized epinephrine reduce symptoms in moderate to severe croup, while humidification has no supporting trial evidence. Because nebulized epinephrine wears off within a few hours, the child is observed for returning stridor before discharge. Albuterol treats bronchospasm, not subglottic swelling, and croup is viral, so antibiotics do not help. Imaging is not needed for a typical presentation and should not delay treatment; her alertness and lack of drooling make epiglottitis less likely.

Look for this next time: For croup with stridor at rest, anticipate a corticosteroid plus nebulized epinephrine, then observe for returning stridor.

Correct answer: D · Target an SpO2 of 88–92% and prepare for noninvasive ventilation

He has acute hypercapnic respiratory acidosis during a COPD exacerbation, worsened by uncontrolled high-concentration oxygen. Current guidance for COPD exacerbations recommends titrating oxygen to a target SpO2 of 88% to 92% in patients at risk of hypercapnia, and noninvasive positive-pressure ventilation is first-line support for acute respiratory acidosis because it reduces intubation and mortality. Keeping the nonrebreather because the SpO2 looks good continues the problem. Stopping oxygen entirely risks dangerous hypoxemia. Bicarbonate does not treat hypoventilation, which is the cause of his acidosis; ventilation does. If he cannot protect his airway or noninvasive ventilation fails, intubation follows.

Look for this next time: In COPD with hypercapnia, target an SpO2 of 88% to 92% and use noninvasive ventilation for acute respiratory acidosis.

Correct answer: B · 2300, when he was last seen without symptoms

For stroke treatment decisions, onset is the time the patient was last known to be at baseline. The CMS stroke quality measure, which cites the AHA/ASA guideline, defines last known well as the time before arrival when the patient was witnessed or reported to be without the signs and symptoms of the current stroke. For someone who wakes with deficits, that is when he was last seen normal, here 2300, not when the symptoms were found. Using 0630 would wrongly place him within standard thrombolysis time windows, and the arrival time or an estimated midnight are not accepted substitutes. Patients with wake-up or unknown-onset stroke may still be treatment candidates based on advanced imaging, so rapid evaluation continues.

Look for this next time: In wake-up stroke, last known well is when the patient was last seen normal, not when the symptoms were discovered.

Correct answer: A · IM midazolam

A convulsive seizure lasting 5 minutes or more is treated as status epilepticus. The American Epilepsy Society's 2016 guideline recommends a benzodiazepine as the initial therapy of choice, specifically IM midazolam, IV lorazepam, or IV diazepam, and found IM midazolam more effective than IV lorazepam in adults without established IV access, because it can be given at once. Waiting for access to give a second-phase drug such as levetiracetam delays first-line treatment. Phenytoin is a second-phase drug and is not given IM. A patient who is actively seizing cannot safely take an oral medication.

Look for this next time: For status epilepticus without IV access, give IM midazolam as the first-line benzodiazepine (AES 2016).

Correct answer: C · Transfuse red cells until the hemoglobin is above 10 g/dL

Suspected variceal bleeding in cirrhosis is managed with a vasoactive drug such as octreotide started at presentation, short-course antibiotic prophylaxis such as ceftriaxone, and endoscopy within 12 hours once the patient is stabilized. Transfusion is restrictive: the 2022 ESGE guideline transfuses at a hemoglobin of 7 g/dL or less with a target of 7 to 9 g/dL, in line with AASLD and Baveno guidance. Transfusing to above 10 g/dL expands blood volume, raises portal pressure, and increases rebleeding and mortality. The octreotide, ceftriaxone, and endoscopy orders are standard parts of his initial care.

Look for this next time: In variceal bleeding, give octreotide and antibiotics, arrange early endoscopy, and transfuse restrictively, around a hemoglobin of 7 g/dL.

Correct answer: A · Abdominal ultrasound

Intermittent colicky pain with drawing up of the legs, lethargy between episodes, vomiting, and bloody mucoid stool in an infant suggest intussusception, which is most common between 6 months and 2 years of age. ACEP's ultrasound guidance names ultrasound as the first-line imaging test for pediatric intussusception, with reported sensitivity and specificity near 98% for radiology-performed studies and no radiation. If the diagnosis is confirmed and there are no signs of perforation or peritonitis, the usual next step is reduction by air or contrast enema. CT adds radiation and is not first-line. An upper GI series looks for malrotation, not ileocolic intussusception. Surgery is reserved for failed reduction or perforation.

Look for this next time: Suspect intussusception in an infant with episodic colicky pain and lethargy; ultrasound is the first-line test.

Correct answer: D · Magnesium sulfate

A seizure with severe hypertension and headache in the weeks after delivery is postpartum eclampsia until proven otherwise; the MSD Manual notes that postpartum preeclampsia develops most often within the first 4 days but sometimes up to 6 weeks after delivery. Magnesium sulfate must be given as soon as eclampsia is diagnosed to prevent recurrent seizures, and it is more effective for this purpose than phenytoin or other anticonvulsants. A benzodiazepine can be added if a seizure continues despite magnesium, but it is not the preventive therapy. The nurse also prepares to treat the severe-range blood pressure and monitors for magnesium toxicity, such as decreased reflexes and hypoventilation.

Look for this next time: Treat eclampsia, including postpartum eclampsia up to 6 weeks after delivery, with magnesium sulfate to prevent further seizures.

Correct answer: C · Speak calmly from a safe distance and acknowledge his frustration

The American Association for Emergency Psychiatry's Project BETA consensus statement on verbal de-escalation (2012) recommends a noncoercive approach to agitation: engage the patient verbally, build a collaborative relationship, and de-escalate, keeping restraint and involuntary medication as last resorts. Staying calm, respecting personal space, keeping an exit open, and acknowledging his frustration often defuse the situation, with security nearby if his behavior changes. Restraints or forced medication now, when he has threatened no one, skip less restrictive options and carry a risk of injury. A threat about losing his place is confrontational and likely to escalate him.

Look for this next time: For an agitated patient who is not yet violent, start with verbal de-escalation; restraint and forced medication are last resorts.

Correct answer: B · Draw a level 4 hours after ingestion and plot it on the nomogram

For a single acute ingestion with a known time, the MSD Manual advises measuring the acetaminophen level 4 or more hours after ingestion and plotting it on the Rumack-Matthew nomogram, because earlier levels may not reflect the peak and cannot be interpreted on the nomogram. Acetylcysteine is most effective when started within 8 hours of ingestion, so a 4-hour level leaves time to act on the result. Early toxicity is often silent, so a lack of symptoms is not reassuring. Waiting for liver enzymes to rise wastes the window in which acetylcysteine prevents liver injury. Her suicide attempt also calls for continuous safety measures and a psychiatric evaluation.

Look for this next time: After a single acute acetaminophen ingestion, draw the level 4 or more hours after ingestion and plot it on the nomogram.

Correct answer: C · IM epinephrine in the outer thigh

Skin and mucosal involvement with bronchospasm and hypotension after exposure to a known allergen is anaphylaxis. The MSD Manual calls epinephrine the cornerstone of treatment, to be given immediately, and notes that absorption is greatest when it is given IM in the anterolateral (mid-outer) thigh. Antihistamines, such as diphenhydramine and the H2 blocker famotidine, relieve itching and hives but do not reverse airway swelling or shock, and they do not replace epinephrine. Glucocorticoids have no proven role in treating the acute reaction. Albuterol can help wheezing that persists after epinephrine, but it does not treat hypotension or laryngeal edema.

Look for this next time: Give IM epinephrine in the anterolateral thigh first for anaphylaxis; antihistamines and steroids are only adjuncts.

Correct answer: D · Clarify the order, replace potassium first, and hold the insulin

Insulin moves potassium into cells, so starting it when potassium is already low can cause dangerous hypokalemia and arrhythmias. The 2024 international consensus report on hyperglycemic crises postpones insulin until potassium is above 3.5 mmol/L, and the MSD Manual uses a threshold of 3.3 mEq/L; at 3.0 mEq/L, both call for replacing potassium first. IV fluids continue, because restoring volume is the first priority and does not drive potassium into cells the way insulin does. Rechecking 4 hours after starting insulin is too late, and an insulin bolus makes the potassium shift worse. The nurse clarifies the order with the provider and follows the DKA protocol.

Look for this next time: In DKA with low potassium, replace potassium before starting insulin, and keep the IV fluids running.

Correct answer: B · Notify the provider urgently and prepare to split or remove the cast

Pain out of proportion to the injury that worsens with passive stretch of the muscles in the compartment suggests acute compartment syndrome. The MSD Manual notes that pulselessness is a late sign, because tissue perfusion can stop long before pulses disappear, so a palpable radial pulse does not exclude it. Initial treatment includes removing any constricting cast or splint, and urgent fasciotomy is needed unless pressure and symptoms improve quickly. More opioids and a 2-hour wait delay recognition while muscle and nerve ischemia progress. Ice over a cast does not relieve compartment pressure.

Look for this next time: Pain out of proportion and pain on passive stretch suggest compartment syndrome; a palpable pulse does not rule it out.

Correct answer: A · Wrap it in moist gauze, bag it, and place the bag in ice water

A cleanly amputated thumb is a candidate for replantation, and how the part is kept affects whether it stays viable. The MSD Manual's first-aid guidance is to wrap the part in damp material such as sterile gauze, seal it in a plastic bag, and place that bag in a second container of water and ice. Cooling slows tissue metabolism, while the bag keeps the tissue out of direct contact with the ice and water. Putting the part directly on ice or in dry ice can freeze and destroy the tissue. MSD also advises against placing the part directly in water or other fluid, which waterlogs the tissue. The nurse labels the bag, keeps it with the patient, covers the stump with a moist dressing, and checks tetanus status.

Look for this next time: Wrap an amputated part in moist gauze, seal it in a plastic bag, and place the bag in ice water; never freeze it.

Correct answer: C · Begin copious irrigation with saline or water now

Drain cleaners are usually strong alkalis, which penetrate deeper and cause more serious injury than acids. The MSD Manual states that chemical burns should be irrigated copiously as soon as possible and without delay, for at least 30 minutes, continuing until the conjunctival pH is in the normal range of 7.0 to 7.2 on pH paper. A topical anesthetic can make irrigation tolerable but should not delay it. Visual acuity and the ophthalmology examination come after irrigation in a chemical burn, because every minute of contact adds tissue damage. Patching the eye traps the chemical against it.

Look for this next time: For a chemical eye splash, irrigate immediately and continue until the conjunctival pH is normal; the acuity check can wait.

Correct answer: C · Give 100% oxygen by nonrebreather and measure carboxyhemoglobin

Several people from one home with headache, nausea, dizziness, and confusion suggest carbon monoxide poisoning. The MSD Manual explains that a standard pulse oximeter cannot tell carboxyhemoglobin from normal hemoglobin, so it gives a falsely high reading, and that the diagnosis is confirmed by measuring carboxyhemoglobin with a CO-oximeter (venous samples are acceptable). Treatment begins with 100% oxygen by nonrebreather mask, which speeds elimination of carbon monoxide, plus supportive care, and hyperbaric oxygen is considered for severe poisoning. Low-flow oxygen or a symptomatic discharge leaves the poisoning untreated and could send the family back into the exposure.

Look for this next time: Pulse oximetry is falsely normal in carbon monoxide poisoning; give 100% oxygen and measure carboxyhemoglobin by CO-oximetry.

Correct answer: D · Airborne precautions in an airborne infection isolation room

Fever with cough, coryza, and conjunctivitis followed by a rash that starts on the face and spreads downward in an unvaccinated child is classic for measles. CDC's clinical overview for health care providers calls for airborne precautions, with the patient in a single-patient airborne infection isolation room and staff wearing an N95 or similarly effective respirator regardless of their own immunity. Patients are contagious from 4 days before to 4 days after rash onset, so she is still infectious. Contact or droplet precautions alone do not stop airborne spread. Exposed patients and staff will also need follow-up.

Look for this next time: Suspected measles needs airborne precautions in an airborne infection isolation room; patients are contagious until 4 days after rash onset.

Correct answer: B · Delayed (yellow)

START sorts adults by walking ability, breathing, respiratory rate, perfusion, and mental status. Patients who can walk are minor (green). For those who cannot, a respiratory rate above 30 per minute, an absent radial pulse or delayed capillary refill, or an inability to follow simple commands makes the patient immediate (red), and a patient who does not breathe even after the airway is repositioned is expectant (black). This patient cannot walk, so he is not minor, but his respiratory rate is below 30, his radial pulse is present, and he obeys commands, so he is delayed (yellow): seriously injured but not expected to deteriorate significantly over several hours. He is reassessed as the scene evolves.

Look for this next time: In START, a nonambulatory adult breathing 30 or fewer times a minute, with a radial pulse and intact commands, is delayed (yellow).

Correct answer: D · Provide a medical screening exam and stabilizing care, regardless of payment

Under EMTALA, a Medicare-participating hospital that offers emergency services must provide a medical screening examination to anyone who comes to the emergency department requesting examination or treatment, including a woman in active labor, regardless of ability to pay. If an emergency medical condition is found, the hospital must provide stabilizing treatment or, if it cannot stabilize the patient within its capability or the patient requests it, arrange an appropriate transfer. Sending her away, requiring a deposit, or limiting screening to insured patients would violate these obligations, which CMS summarizes in its EMTALA overview. The nurse escalates the clerk's suggestion at once so that screening begins.

Look for this next time: EMTALA requires a medical screening exam and stabilizing care for anyone who comes to the ED, regardless of ability to pay.