10 free Paramedic practice questions: Dysrhythmia Recognition and Management

The radial count ran over too short an interval to be valid: A short count is a real problem with an irregular rhythm, because the beats are not evenly spaced. This radial pulse was counted over a full minute, which is how an irregular rhythm should be counted.

The monitor is counting artifact along with the true complexes: Artifact makes a tracing look messy, usually with spikes that do not fit the rhythm. This tracing is a clean irregularly irregular rhythm, so artifact does not explain the gap between the two rates.

The patient converted between the two measurements: Converting to a new rhythm would change what the monitor shows. Conversion does not give you two different rates from the same rhythm at the same moment.

Second degree atrioventricular block type I: Second degree type I, also called Wenckebach, drops beats too. In type I, the PR interval gets longer with each conducted beat until one P wave does not conduct. This strip gives no warning. The PR interval stays fixed on every conducted beat before the drop, and a fixed PR interval points to a block below the AV node.

First degree atrioventricular block: First degree block only makes the PR interval longer than 0.20 seconds. Every P wave still conducts a QRS, and no beats drop. This strip has P waves with no QRS after them, so conduction is failing outright, not just slowing at the node.

Third degree atrioventricular block: Third degree block is complete AV dissociation. The atria and the ventricles each beat on their own, with no fixed link between the P waves and the QRS complexes. This strip keeps the same PR interval on every conducted beat. The constant PR interval shows some P waves are still getting through to the ventricles.

Adenosine 12 mg as the first dose, since a wide rhythm needs the larger dose: Adenosine can be used for a wide complex tachycardia that is regular and monomorphic. The problem is the 12 mg first dose. The first dose is 6 mg no matter how wide the QRS is, and 12 mg comes only if 6 mg fails. Adenosine is never for an irregular or polymorphic wide complex rhythm.

Verapamil, since the young age makes a supraventricular origin likely: Verapamil is a calcium channel blocker, and it is meant for rhythms that start above the ventricles. Young patients still get ventricular tachycardia. Giving verapamil on a guess about age can drop the blood pressure out from under the rhythm.

Synchronized cardioversion, since any wide complex rhythm is unstable: Synchronized cardioversion is the right call for an unstable patient. This patient is alert, warm, and dry with a systolic pressure of 118, which is stable. Sedating and shocking a stable patient skips a step that a drug can handle.

Albuterol by nebulizer at a high dose: Albuterol does move potassium into the cells. Albuterol takes time to work, and this rhythm does not have time while the QRS keeps getting wider.

Sodium bicarbonate by intravenous push: Sodium bicarbonate also shifts potassium into the cells. Like the other shifting drugs, sodium bicarbonate is an add on that follows calcium once the membrane is already unstable.

Atropine by intravenous push: Atropine is the usual drug for a slow heart rate like 52, and atropine works by blocking vagal tone. Vagal tone is not what is slowing this heart. Potassium has slowed the conduction system, and atropine does nothing for the cell membrane. Calcium does, and the heart rate improves once the membrane is stable.

A regular rhythm with a sawtooth baseline pattern: A sawtooth baseline with a regular rhythm is atrial flutter. Atrial flutter is one organized circuit looping around the atrium at a fixed rate. Flutter conducts in a set ratio, like 2:1 or 3:1, so flutter has a repeating pattern you can measure. Atrial fibrillation has no pattern.

An irregular rhythm with P waves of changing shape before each QRS complex: An irregular rhythm with P waves that change shape is a wandering atrial pacemaker. The pacemaker site moves between different spots in the atria, so each P wave looks different. A P wave still comes before each QRS. Atrial fibrillation has no P waves to find, so any discrete P wave rules atrial fibrillation out.

A narrow, regular rhythm at 180 with no visible P waves: A narrow, regular rhythm at 180 is supraventricular tachycardia (SVT). At that speed, the P waves are hidden in or behind the QRS. No visible P waves fits both rhythms. What separates SVT from atrial fibrillation is regularity. SVT is regular, and atrial fibrillation never is.

Progressive lengthening of the PR interval with each beat until a QRS complex is dropped: A PR interval that gets longer each beat until a QRS drops is second-degree type I, also called Wenckebach. The AV node gets a little more tired with each beat until one beat does not get through. Then the AV node recovers and the pattern starts over. In Wenckebach, the P waves and the QRS complexes are still connected. The connection just gets worse each beat. Complete block has no connection at all.

A constant PR interval on conducted beats with an occasional dropped QRS complex: A constant PR interval with an occasional dropped QRS is second-degree type II. The block is below the AV node and is all or nothing. The conducted beats have a fixed PR interval, so some beats are still getting through. Complete block conducts nothing.

Absence of discernible P waves accompanied by an irregularly irregular ventricular response: No P waves with an irregularly irregular ventricular rate is atrial fibrillation. Complete heart block does have P waves, and they are regular. The R-R interval in complete block is regular too, because the escape pacemaker is steady.

Vagal maneuvers followed by reassessment before any further intervention: Vagal maneuvers stimulate the vagus nerve to slow conduction through the AV node. Vagal maneuvers are the right first step in stable, narrow-complex SVT. With a blood pressure of 74/42 and confusion, this patient cannot tolerate the delay.

Adenosine administration only, with no further escalation planned: Adenosine blocks conduction through the AV node and is the drug of choice for stable, regular, narrow-complex SVT. This patient is unstable, with a blood pressure of 74/42, confusion, and diaphoresis. For an unstable patient, the tachycardia algorithm calls for cardioversion instead of a drug alone. Adenosine only, with no plan to escalate, treats the rhythm while the poor perfusion goes on.

Supportive care, oxygen, and transport with continuous monitoring only: Oxygen and monitoring fit a patient who is tachycardic but still perfusing well and tolerating the rate. This patient already has a blood pressure of 74/42, confusion, and cool, diaphoretic skin. Monitoring alone holds back the cardioversion this patient needs to fix the rhythm causing the low blood pressure.

Aortic dissection: causes sudden tearing pain, often into the back. You may find a difference in blood pressure or pulse between the arms, a new murmur, or a neurologic deficit. This patient's pain is sharp and changes with position. Dissection pain does not ease when the patient sits up and leans forward. The pain also followed a viral illness instead of starting at full strength, and the vital signs are normal.

Anterior myocardial infarction: An anterior MI shows ST elevation in the anterior chest leads, with reciprocal depression in the inferior leads. The patient usually has pressure-like discomfort. Two findings rule an anterior MI out here. The ST elevation crosses nearly every lead group, and no single coronary artery supplies all of those areas. There are also no reciprocal depressions at all. A blocked artery injures one area, and the opposite wall shows the reciprocal change. Pericarditis inflames the whole pericardium, so no healthy opposite wall is left to show one.

Pulmonary embolism: A pulmonary embolism causes sudden pleuritic pain, which is sharp pain that gets worse with breathing. Trouble breathing, a fast heart rate, and low oxygen come with it. There is usually a risk factor like recent immobility, surgery, or cancer. Pleuritic pain does overlap with pericarditis. This patient's lungs are clear, the neck veins are flat, and the respiratory rate is 18. The pain is positional, not just pleuritic. A pulmonary embolism also does not cause diffuse ST elevation with PR depression.

Amiodarone 150 mg over 10 minutes: Amiodarone belongs to a stable wide-complex tachycardia, like ventricular tachycardia with a pulse. In that rhythm the problem starts below the atrioventricular node, and a drug that blocks the node would do nothing. The complexes here are narrow. Narrow complexes put the origin above the ventricles and put this patient on a different branch of the algorithm. Adenosine also treats and diagnoses within seconds. Amiodarone is a 10 minute infusion aimed at a ventricular rhythm this patient does not have.

Adenosine 12 mg rapid intravenous push: Adenosine 12 mg is the right dose, just not the first one. The 12 mg dose follows when a 6 mg dose, pushed correctly, has failed to convert the rhythm. Jumping to 12 mg gives more drug than needed. The patient also gets more of the side effects, like chest pressure, flushing, a brief sense of doom, and a pause of several seconds. Both doses are the same drug with the same mechanism, and the 6 mg dose comes first.

Synchronized cardioversion at 100 J: Synchronized cardioversion is for an unstable narrow-complex tachycardia. Unstable means hypotension, altered mental status, ischemic chest discomfort, or acute heart failure caused by the fast rate. This patient is alert, with warm dry skin, clear lungs, and a pressure of 118/74. Mild lightheadedness at a rate of 186 does not make this patient unstable. A stable patient gets a drug before electricity and the sedation that comes with cardioversion.

Administer epinephrine 0.01 mg/kg intravenously: Epinephrine 0.01 mg/kg IV is the main drug for an infant with bradycardia and poor perfusion. Epinephrine does not replace compressions. This infant's rate is still below 60 with poor perfusion after good ventilation, and that is the point where compressions start. Start compressions now, then give epinephrine if the bradycardia continues.

Administer atropine 0.02 mg/kg intravenously: Atropine 0.02 mg/kg is for bradycardia from increased vagal tone, like during suctioning, or from a primary AV block. The monitor shows sinus bradycardia, not a heart block. This infant became unresponsive after three days of vomiting and poor feeding. The slow rate here points to hypoxia, and blocking the vagus nerve does not fix hypoxia.

Initiate transcutaneous pacing at 100: Transcutaneous pacing is considered for bradycardia that does not respond to oxygenation, ventilation, and drugs, like complete heart block. This monitor shows sinus bradycardia, not complete heart block. This infant has not had compressions or any drug yet.