Electrical Therapy Flashcard
Rationale
C. Rationale: When an arrhythmia reoccurs later during a resuscitation attempt, a shock should be delivered at the energy level that was previously successful.
Question
A patient was successfully defibrillated, terminating pulseless ventricular tachycardia. One minute later, the patient again goes into ventricular tachycardia and loses his pulse. A shock should be delivered at:
A. The lowest energy level, building from there
B. The highest energy level available
C. The same energy that was successful initially
D. 200 Joules
Answer
C. The same energy that was successful initially
Rationale
D. Rationale: An AED should be used when the patient is unresponsive, does not have a pulse, and is breathing abnormally or not breathing at all. Abnormal breaths (e.g., agonal gasps) should not be mistaken for adequate breathing.
Question
An AED should be used when:
A. The patient is unresponsive
B. The patient is apneic or breathing abnormally (e.g., gasping)
C. The patient does not have a pulse
D. All of the above
Answer
D. All of the above
Rationale
B. Rationale: Defibrillation works by stunning the heart, briefly terminating electrical activity, and allowing the heart’s normal pacemaker to resume its normal activity. Following successful defibrillation, most patients will have an abnormal rhythm of some type (often bradycardia) that does not perfuse well. The patient often needs ongoing CPR until normal cardiac activity is restored. Early defibrillation is critical because the likelihood of successful defibrillation decreases over time. Untreated VF will deteriorate to asystole.
Question
Choose the correct statement concerning defibrillation:
A. Following successful defibrillation, most patients have a normal and adequately perfusing rhythm.
B. Defibrillation works by stunning the heart, briefly terminating electrical activity, and allowing the heart’s normal pacemaker to resume activity.
C. The probability of successful defibrillation increases over time.
D. Ventricular fibrillation rarely deteriorates to asystole.
Answer
B. Defibrillation works by stunning the heart, briefly terminating electrical activity, and allowing the heart’s normal pacemaker to resume activity.
Rationale
D. Rationale: Research does not support the use of self-adhesive pads over paddles, but self-adhesive pads do reduce the risk of arcing. They also allow monitoring of the patient’s underlying rhythm. Both paddles with a conducting jelly and self-adhesive pads reduce transthoracic impedance, described as the resistance of chest structures to electrical current. Self-adhesive pads may permit shocks to be delivered more rapidly as well.
Question
Self-adhesive AED pads:
A. Reduce the risk of arcing
B. Reduce transthoracic impedance
C. Permit monitoring of the patient’s heart rhythm
D. All of these
Answer
D. All of these
Rationale
A. Rationale: Whether an AED or a manual defibrillator is used, shocks delivered to the patient of VF/pulseless VT are unsynchronized. When a patient is in VF or pulseless VT, high-quality CPR should be provided until pads have been placed and the defibrillator (whether an AED or a manual defibrillator) is ready to shock. Minimize any interruptions in CPR.
Question
Shocks delivered to the patient in VF or pulseless VT should be:
A. Unsynchronized
B. Synchronized
C. Either synchronized or unsynchronized as long as the patient receives the shock
D. Delayed until the patient has been provided with 3–5 minutes of high-quality CPR
Answer
A. Unsynchronized
Rationale
C. Rationale: Synchronized cardioversion is used for patients with unstable VT, unstable atrial fibrillation/flutter, and unstable regular monomorphic tachycardia with a pulse. Defibrillation is used for pulseless rhythms, polymorphic VT when a delay in converting the rhythm may lead to cardiac arrest, and monomorphic or polymorphic VT in an unstable patient.
Question
Synchronized cardioversion is recommended for:
A. Monomorphic or polymorphic VT in an unstable patient
B. Pulseless rhythms
C. Unstable tachycardia with a pulse
D. Polymorphic VT
Answer
C. Unstable tachycardia with a pulse
Rationale
B. Rationale: The patient in atrial fibrillation with a heart rate of 155 bpm experiencing acute shortness of breath and pulmonary edema will likely require cardioversion. Any patient with acute-onset shortness of breath, hypotension, and pulmonary edema related to a rapid heart rate is unstable and will require cardioversion.
Question
Which of the following patients is likely to require cardioversion?
A. An otherwise healthy patient in atrial flutter with a heart rate of 150 bpm and no symptoms aside from palpitations
B. A patient with new-onset atrial fibrillation at a rate of 155 bpm with acute shortness of breath, hypotension, and pulmonary edema
C. An adolescent patient with a high fever and a heart rate of 130 bpm
D. A patient with known paroxysmal supraventricular tachycardia with a history of responding well to IV adenosine
Answer
B. A patient with new-onset atrial fibrillation at a rate of 155 bpm with acute shortness of breath, hypotension, and pulmonary edema
Rationale
D. Rationale: Synchronized cardioversion requires a lower energy level than defibrillation. Doses of energy in synchronized cardioversion generally range between 50 and 200 Joules.
Question
Which of the following statements regarding synchronized cardioversion is INCORRECT?
A. In synchronized cardioversion, the shock is delivered at the peak of the R wave, which avoids delivery of the shock during repolarization.
B. Low-energy shocks should always be delivered as synchronized shocks to avoid precipitating VF.
C. Synchronization can take longer than defibrillation because the sensor must detect the peak of the R waves.
D. Synchronized cardioversion requires a higher energy level than defibrillation.
Answer
D. Synchronized cardioversion requires a higher energy level than defibrillation.