AHA ACLS Post-Test Answer Key 2026/2027 Edition |
American Heart Association Guidelines Update | with Verified
Solutions and Detailed Rationales — 250 Questions
Section 1: Basic Life Support (BLS) and CPR (Questions 1-25)
1 During a witnessed cardiac arrest in a monitored unit, the rhythm is initially ventricular tachycardia (pulseless).
A defibrillator is immediately available. According to the 2026/2027 AHA guidelines, what is the optimal
sequence of actions for a single rescuer until additional help arrives?
A) Immediately start chest compressions, then analyze rhythm, then defibrillate, then resume compressions.
B) Check pulse for up to 10 seconds, then defibrillate immediately, then start chest compressions.
C) Verify unresponsiveness, activate emergency response, get defibrillator, then analyze rhythm and defibrillate
if shockable.
D) Start chest compressions at a rate of 100-120/min, then after 2 minutes analyze rhythm, then defibrillate.
Answer: C
Rationale: The correct sequence for a witnessed arrest with immediate defibrillator access is: verify
unresponsiveness, activate emergency response, retrieve defibrillator, then analyze rhythm and deliver shock if
indicated. Starting compressions before rhythm analysis delays defibrillation, which is critical for shockable
rhythms. Options A and D delay defibrillation; option B suggests pulse check first, which is not recommended in
witnessed arrest with immediate defibrillator.
2 A team is performing CPR on a patient with suspected opioid overdose. The patient has a pulse but is not
breathing adequately. What is the most appropriate BLS intervention according to the 2026/2027 guidelines?
A) Immediately begin chest compressions at a rate of 100-120/min until naloxone is administered.
B) Provide rescue breaths at a rate of 1 breath every 5-6 seconds, reassess pulse frequently.
C) Administer naloxone intramuscularly and then reassess breathing before starting CPR.
D) Deliver two initial rescue breaths, then begin chest compressions if breathing does not improve.
Answer: B
Rationale: For a patient with a pulse but inadequate breathing (respiratory arrest), the appropriate BLS intervention
is rescue breathing. The recommended rate is 1 breath every 5-6 seconds (10-12 breaths per minute), with frequent
pulse checks. Chest compressions are not indicated when a pulse is present. Naloxone may be given but should not
delay ventilation. Options A and D include unnecessary compressions; option C delays ventilation.
3 In a cardiac arrest situation with an advanced airway in place, you are providing continuous chest compressions
at a rate of 110/min. What ventilation rate should be delivered to optimize coronary perfusion pressure while
avoiding hyperventilation?
A) 6 breaths per minute (1 breath every 10 seconds)
B) 8-10 breaths per minute (1 breath every 6-8 seconds)
C) 12-15 breaths per minute (1 breath every 4-5 seconds)
D) 20 breaths per minute (1 breath every 3 seconds)
Answer: B
Rationale: With an advanced airway, continuous compressions are performed at 100-120/min, and ventilations are
delivered at 8-10 breaths per minute (1 breath every 6-8 seconds). This rate prevents hyperventilation, which can
increase intrathoracic pressure and decrease venous return, reducing coronary perfusion pressure. Option A (6/min)
may be too low; options C and D risk hyperventilation.
,4 During CPR, a team member notes that the end-tidal CO2 (ETCO2) reading is persistently below 10 mmHg
despite high-quality compressions. What is the most likely implication for BLS quality?
A) Compression rate is too fast, causing inadequate filling time.
B) Compression depth is insufficient, leading to poor cardiac output.
C) Ventilation rate is too high, causing respiratory alkalosis.
D) Chest recoil is incomplete, reducing venous return and cardiac output.
Answer: D
Rationale: Low ETCO2 (<10 mmHg) during CPR indicates low cardiac output, often due to incomplete chest recoil.
Incomplete recoil prevents negative intrathoracic pressure during decompression, reducing venous return and
subsequent cardiac output. While compression depth and rate are important, persistent low ETCO2 despite
adequate depth and rate should prompt evaluation of recoil. Ventilation rate affects ETCO2 but is less likely to
cause such a low value if compressions are effective.
5 A team of two rescuers is performing CPR on an adult in cardiac arrest. The compressor is delivering
compressions at a depth of 2.2 inches and a rate of 110/min. The ventilations are given as 2 breaths after every
30 compressions. What is the most critical adjustment needed to improve CPR quality according to the
2026/2027 guidelines?
A) Increase compression rate to 120/min to maximize blood flow.
B) Switch to continuous compressions with asynchronous ventilations if an advanced airway is placed.
C) Reduce compression depth to 2 inches to avoid injury.
D) Change compression-to-ventilation ratio to 15:2 to increase ventilation frequency.
Answer: B
Rationale: The scenario describes two-rescuer CPR without an advanced airway; the ratio is 30:2. However, the
critical adjustment is to consider placing an advanced airway to allow continuous compressions without pauses for
ventilations. Continuous compressions improve coronary perfusion pressure. Increasing rate beyond 110 is not
recommended; depth of 2.2 inches is within the 2-2.4 inch range. Changing to 15:2 is not standard for adults and
would increase interruptions.
6 In a witnessed cardiac arrest with a shockable rhythm, the first shock is delivered. Immediately after the shock,
the rescuer should:
A) Check the rhythm and pulse for 10 seconds to assess ROSC.
B) Resume chest compressions immediately for 2 minutes before rhythm check.
C) Deliver a second shock if the rhythm remains shockable.
D) Administer epinephrine 1 mg IV/IO immediately after the shock.
Answer: B
Rationale: After defibrillation, the immediate priority is to resume chest compressions without delay. Rhythm and
pulse checks should be deferred for 2 minutes (5 cycles of 30:2) to minimize interruptions in compressions.
Delivering a second shock immediately or checking rhythm/pulse prematurely interrupts compressions.
Epinephrine is given after the second shock (if rhythm remains shockable) or during the 2-minute cycle.
7 Which of the following best describes the physiological rationale for using a compression-to-ventilation ratio of
30:2 in single-rescuer adult CPR?
A) It maximizes minute ventilation to prevent hypoxia during cardiac arrest.
B) It balances the need for coronary perfusion pressure with minimal interruptions in compressions.
C) It ensures that the rescuer does not fatigue quickly by alternating tasks.
D) It is derived from animal studies showing optimal survival with 5 compressions per ventilation.
,Answer: B
Rationale: The 30:2 ratio is designed to provide adequate ventilation while minimizing interruptions in chest
compressions. Interruptions reduce coronary perfusion pressure and cardiac output. The ratio allows for
approximately 2 minutes of CPR (5 cycles) before rhythm check. Option A is incorrect because ventilation is less
critical initially; option C is a practical consideration but not the primary rationale; option D is false (30:2 is based
on human studies).
8 A patient in cardiac arrest has a return of spontaneous circulation (ROSC) after 8 minutes of CPR. The team
notes that the patient is unresponsive with agonal gasps. What is the immediate BLS priority?
A) Begin rescue breathing at 10-12 breaths per minute with supplemental oxygen.
B) Start chest compressions again because agonal gasps are not adequate breathing.
C) Administer naloxone in case opioid overdose is contributing.
D) Place the patient in the recovery position to maintain airway patency.
Answer: A
Rationale: After ROSC, the patient has a pulse but inadequate breathing (agonal gasps). The immediate priority is to
provide rescue breathing with supplemental oxygen to maintain oxygenation. Chest compressions are not indicated
because a pulse is present. Naloxone is not indicated unless opioid overdose is suspected; the recovery position is
not appropriate for an unresponsive patient with inadequate breathing.
9 During CPR, the compressor switches roles with the ventilator every 2 minutes. What is the primary purpose of
this rotation?
A) To allow the compressor to rest and maintain compression quality.
B) To ensure that the ventilator has practice with compressions.
C) To reduce the risk of rescuer fatigue and maintain effective compressions.
D) To distribute the workload evenly among team members.
Answer: C
Rationale: Compression quality deteriorates after about 2 minutes due to rescuer fatigue, leading to inadequate depth
and rate. Rotating compressors every 2 minutes helps maintain high-quality compressions throughout resuscitation.
While options A and D are related, the primary evidence-based reason is to prevent fatigue-related decline in
compression quality. Option B is not a goal.
10 A patient with a suspected cervical spine injury is found unresponsive, not breathing, and pulseless. Two
rescuers are present. How should BLS be modified?
A) Use a jaw-thrust maneuver without head tilt to open the airway, and begin chest compressions.
B) Use a head-tilt chin-lift to ensure adequate airway, as cervical spine injury is not a priority.
C) Perform chest compressions only, without rescue breaths, to avoid moving the neck.
D) Place a cervical collar before starting any BLS interventions.
Answer: A
Rationale: In suspected cervical spine injury, the airway should be opened using a jaw-thrust maneuver without head
tilt to minimize spine movement. Chest compressions are started immediately. Rescue breaths are still given using
the jaw-thrust. Option B is incorrect because head-tilt may worsen injury; option C is wrong because ventilations
are necessary; option D delays critical interventions.
11 A patient in respiratory arrest has a pulse of 50 bpm and is receiving bag-mask ventilation with a clear airway.
The rescuer notices that the chest rises inadequately despite a good mask seal. Which action should be
prioritized to improve ventilation effectiveness?
A) Increase the ventilation rate to 12 breaths/min
, B) Reopen the airway using the head-tilt, chin-lift maneuver and ensure a two-handed mask hold
C) Insert an oropharyngeal airway and switch to a supraglottic airway device
D) Administer 100% oxygen via non-rebreather mask while maintaining current rate
Answer: B
Rationale: Inadequate chest rise despite good mask seal most often indicates airway obstruction or improper head
positioning. Reopening the airway with head-tilt, chin-lift and using a two-handed mask hold improves seal and
airway patency. Increasing ventilation rate (A) does not address the underlying obstruction; inserting an airway (C)
may be considered after basic maneuvers fail; (D) is inappropriate for a patient in respiratory arrest requiring
positive pressure ventilation.
12 During a resuscitation attempt, the cardiac monitor shows asystole. The team leader orders high-quality CPR
and IV epinephrine 1 mg. After 2 minutes of CPR, the rhythm remains asystole. What is the next appropriate
intervention?
A) Administer a second dose of epinephrine 1 mg and continue CPR
B) Attempt defibrillation with 200 J biphasic
C) Administer amiodarone 300 mg IV push
D) Place an advanced airway and pause CPR for rhythm analysis every 30 seconds
Answer: A
Rationale: For asystole, defibrillation is not indicated (B). The algorithm calls for epinephrine every 3-5 minutes;
after 2 minutes of CPR, a second dose is appropriate. Amiodarone (C) is for shockable rhythms. (D) is incorrect
because pauses should be minimized; continuous CPR with rhythm checks every 2 minutes is standard.
13 A rescuer is performing single-rescuer CPR on an adult victim. The rescuer delivers 30 compressions and 2
breaths. After 5 cycles, the rescuer notices the victim's chest does not rise with each breath. What is the most
likely cause of ineffective ventilation?
A) Compression rate is too fast, reducing cardiac output
B) The rescuer is not tilting the head back sufficiently to open the airway
C) The rescuer is using too much force during compressions, causing gastric insufflation
D) The ventilation volume is excessive, leading to airway obstruction
Answer: B
Rationale: In single-rescuer CPR, inadequate head tilt is a common cause of airway obstruction and ineffective
ventilation. (A) affects compressions, not ventilation; (C) and (D) are less common; proper head-tilt chin-lift is
essential for opening the airway.
14 A healthcare provider is called to assess an unresponsive adult. The provider checks for responsiveness,
activates emergency response, and checks breathing and pulse simultaneously. The provider feels a weak
carotid pulse but notes the patient is not breathing normally. What is the immediate next step?
A) Begin high-quality chest compressions at a rate of 100-120/min
B) Provide rescue breathing at a rate of 10-12 breaths/min without compressions
C) Apply an AED and analyze the rhythm
D) Reposition the airway and recheck pulse for up to 10 seconds
Answer: B
Rationale: The patient has a pulse but is not breathing normally, indicating respiratory arrest. The appropriate action
is rescue breathing without compressions. (A) is for cardiac arrest; (C) is for pulseless patients; (D) delays
ventilation unnecessarily.
American Heart Association Guidelines Update | with Verified
Solutions and Detailed Rationales — 250 Questions
Section 1: Basic Life Support (BLS) and CPR (Questions 1-25)
1 During a witnessed cardiac arrest in a monitored unit, the rhythm is initially ventricular tachycardia (pulseless).
A defibrillator is immediately available. According to the 2026/2027 AHA guidelines, what is the optimal
sequence of actions for a single rescuer until additional help arrives?
A) Immediately start chest compressions, then analyze rhythm, then defibrillate, then resume compressions.
B) Check pulse for up to 10 seconds, then defibrillate immediately, then start chest compressions.
C) Verify unresponsiveness, activate emergency response, get defibrillator, then analyze rhythm and defibrillate
if shockable.
D) Start chest compressions at a rate of 100-120/min, then after 2 minutes analyze rhythm, then defibrillate.
Answer: C
Rationale: The correct sequence for a witnessed arrest with immediate defibrillator access is: verify
unresponsiveness, activate emergency response, retrieve defibrillator, then analyze rhythm and deliver shock if
indicated. Starting compressions before rhythm analysis delays defibrillation, which is critical for shockable
rhythms. Options A and D delay defibrillation; option B suggests pulse check first, which is not recommended in
witnessed arrest with immediate defibrillator.
2 A team is performing CPR on a patient with suspected opioid overdose. The patient has a pulse but is not
breathing adequately. What is the most appropriate BLS intervention according to the 2026/2027 guidelines?
A) Immediately begin chest compressions at a rate of 100-120/min until naloxone is administered.
B) Provide rescue breaths at a rate of 1 breath every 5-6 seconds, reassess pulse frequently.
C) Administer naloxone intramuscularly and then reassess breathing before starting CPR.
D) Deliver two initial rescue breaths, then begin chest compressions if breathing does not improve.
Answer: B
Rationale: For a patient with a pulse but inadequate breathing (respiratory arrest), the appropriate BLS intervention
is rescue breathing. The recommended rate is 1 breath every 5-6 seconds (10-12 breaths per minute), with frequent
pulse checks. Chest compressions are not indicated when a pulse is present. Naloxone may be given but should not
delay ventilation. Options A and D include unnecessary compressions; option C delays ventilation.
3 In a cardiac arrest situation with an advanced airway in place, you are providing continuous chest compressions
at a rate of 110/min. What ventilation rate should be delivered to optimize coronary perfusion pressure while
avoiding hyperventilation?
A) 6 breaths per minute (1 breath every 10 seconds)
B) 8-10 breaths per minute (1 breath every 6-8 seconds)
C) 12-15 breaths per minute (1 breath every 4-5 seconds)
D) 20 breaths per minute (1 breath every 3 seconds)
Answer: B
Rationale: With an advanced airway, continuous compressions are performed at 100-120/min, and ventilations are
delivered at 8-10 breaths per minute (1 breath every 6-8 seconds). This rate prevents hyperventilation, which can
increase intrathoracic pressure and decrease venous return, reducing coronary perfusion pressure. Option A (6/min)
may be too low; options C and D risk hyperventilation.
,4 During CPR, a team member notes that the end-tidal CO2 (ETCO2) reading is persistently below 10 mmHg
despite high-quality compressions. What is the most likely implication for BLS quality?
A) Compression rate is too fast, causing inadequate filling time.
B) Compression depth is insufficient, leading to poor cardiac output.
C) Ventilation rate is too high, causing respiratory alkalosis.
D) Chest recoil is incomplete, reducing venous return and cardiac output.
Answer: D
Rationale: Low ETCO2 (<10 mmHg) during CPR indicates low cardiac output, often due to incomplete chest recoil.
Incomplete recoil prevents negative intrathoracic pressure during decompression, reducing venous return and
subsequent cardiac output. While compression depth and rate are important, persistent low ETCO2 despite
adequate depth and rate should prompt evaluation of recoil. Ventilation rate affects ETCO2 but is less likely to
cause such a low value if compressions are effective.
5 A team of two rescuers is performing CPR on an adult in cardiac arrest. The compressor is delivering
compressions at a depth of 2.2 inches and a rate of 110/min. The ventilations are given as 2 breaths after every
30 compressions. What is the most critical adjustment needed to improve CPR quality according to the
2026/2027 guidelines?
A) Increase compression rate to 120/min to maximize blood flow.
B) Switch to continuous compressions with asynchronous ventilations if an advanced airway is placed.
C) Reduce compression depth to 2 inches to avoid injury.
D) Change compression-to-ventilation ratio to 15:2 to increase ventilation frequency.
Answer: B
Rationale: The scenario describes two-rescuer CPR without an advanced airway; the ratio is 30:2. However, the
critical adjustment is to consider placing an advanced airway to allow continuous compressions without pauses for
ventilations. Continuous compressions improve coronary perfusion pressure. Increasing rate beyond 110 is not
recommended; depth of 2.2 inches is within the 2-2.4 inch range. Changing to 15:2 is not standard for adults and
would increase interruptions.
6 In a witnessed cardiac arrest with a shockable rhythm, the first shock is delivered. Immediately after the shock,
the rescuer should:
A) Check the rhythm and pulse for 10 seconds to assess ROSC.
B) Resume chest compressions immediately for 2 minutes before rhythm check.
C) Deliver a second shock if the rhythm remains shockable.
D) Administer epinephrine 1 mg IV/IO immediately after the shock.
Answer: B
Rationale: After defibrillation, the immediate priority is to resume chest compressions without delay. Rhythm and
pulse checks should be deferred for 2 minutes (5 cycles of 30:2) to minimize interruptions in compressions.
Delivering a second shock immediately or checking rhythm/pulse prematurely interrupts compressions.
Epinephrine is given after the second shock (if rhythm remains shockable) or during the 2-minute cycle.
7 Which of the following best describes the physiological rationale for using a compression-to-ventilation ratio of
30:2 in single-rescuer adult CPR?
A) It maximizes minute ventilation to prevent hypoxia during cardiac arrest.
B) It balances the need for coronary perfusion pressure with minimal interruptions in compressions.
C) It ensures that the rescuer does not fatigue quickly by alternating tasks.
D) It is derived from animal studies showing optimal survival with 5 compressions per ventilation.
,Answer: B
Rationale: The 30:2 ratio is designed to provide adequate ventilation while minimizing interruptions in chest
compressions. Interruptions reduce coronary perfusion pressure and cardiac output. The ratio allows for
approximately 2 minutes of CPR (5 cycles) before rhythm check. Option A is incorrect because ventilation is less
critical initially; option C is a practical consideration but not the primary rationale; option D is false (30:2 is based
on human studies).
8 A patient in cardiac arrest has a return of spontaneous circulation (ROSC) after 8 minutes of CPR. The team
notes that the patient is unresponsive with agonal gasps. What is the immediate BLS priority?
A) Begin rescue breathing at 10-12 breaths per minute with supplemental oxygen.
B) Start chest compressions again because agonal gasps are not adequate breathing.
C) Administer naloxone in case opioid overdose is contributing.
D) Place the patient in the recovery position to maintain airway patency.
Answer: A
Rationale: After ROSC, the patient has a pulse but inadequate breathing (agonal gasps). The immediate priority is to
provide rescue breathing with supplemental oxygen to maintain oxygenation. Chest compressions are not indicated
because a pulse is present. Naloxone is not indicated unless opioid overdose is suspected; the recovery position is
not appropriate for an unresponsive patient with inadequate breathing.
9 During CPR, the compressor switches roles with the ventilator every 2 minutes. What is the primary purpose of
this rotation?
A) To allow the compressor to rest and maintain compression quality.
B) To ensure that the ventilator has practice with compressions.
C) To reduce the risk of rescuer fatigue and maintain effective compressions.
D) To distribute the workload evenly among team members.
Answer: C
Rationale: Compression quality deteriorates after about 2 minutes due to rescuer fatigue, leading to inadequate depth
and rate. Rotating compressors every 2 minutes helps maintain high-quality compressions throughout resuscitation.
While options A and D are related, the primary evidence-based reason is to prevent fatigue-related decline in
compression quality. Option B is not a goal.
10 A patient with a suspected cervical spine injury is found unresponsive, not breathing, and pulseless. Two
rescuers are present. How should BLS be modified?
A) Use a jaw-thrust maneuver without head tilt to open the airway, and begin chest compressions.
B) Use a head-tilt chin-lift to ensure adequate airway, as cervical spine injury is not a priority.
C) Perform chest compressions only, without rescue breaths, to avoid moving the neck.
D) Place a cervical collar before starting any BLS interventions.
Answer: A
Rationale: In suspected cervical spine injury, the airway should be opened using a jaw-thrust maneuver without head
tilt to minimize spine movement. Chest compressions are started immediately. Rescue breaths are still given using
the jaw-thrust. Option B is incorrect because head-tilt may worsen injury; option C is wrong because ventilations
are necessary; option D delays critical interventions.
11 A patient in respiratory arrest has a pulse of 50 bpm and is receiving bag-mask ventilation with a clear airway.
The rescuer notices that the chest rises inadequately despite a good mask seal. Which action should be
prioritized to improve ventilation effectiveness?
A) Increase the ventilation rate to 12 breaths/min
, B) Reopen the airway using the head-tilt, chin-lift maneuver and ensure a two-handed mask hold
C) Insert an oropharyngeal airway and switch to a supraglottic airway device
D) Administer 100% oxygen via non-rebreather mask while maintaining current rate
Answer: B
Rationale: Inadequate chest rise despite good mask seal most often indicates airway obstruction or improper head
positioning. Reopening the airway with head-tilt, chin-lift and using a two-handed mask hold improves seal and
airway patency. Increasing ventilation rate (A) does not address the underlying obstruction; inserting an airway (C)
may be considered after basic maneuvers fail; (D) is inappropriate for a patient in respiratory arrest requiring
positive pressure ventilation.
12 During a resuscitation attempt, the cardiac monitor shows asystole. The team leader orders high-quality CPR
and IV epinephrine 1 mg. After 2 minutes of CPR, the rhythm remains asystole. What is the next appropriate
intervention?
A) Administer a second dose of epinephrine 1 mg and continue CPR
B) Attempt defibrillation with 200 J biphasic
C) Administer amiodarone 300 mg IV push
D) Place an advanced airway and pause CPR for rhythm analysis every 30 seconds
Answer: A
Rationale: For asystole, defibrillation is not indicated (B). The algorithm calls for epinephrine every 3-5 minutes;
after 2 minutes of CPR, a second dose is appropriate. Amiodarone (C) is for shockable rhythms. (D) is incorrect
because pauses should be minimized; continuous CPR with rhythm checks every 2 minutes is standard.
13 A rescuer is performing single-rescuer CPR on an adult victim. The rescuer delivers 30 compressions and 2
breaths. After 5 cycles, the rescuer notices the victim's chest does not rise with each breath. What is the most
likely cause of ineffective ventilation?
A) Compression rate is too fast, reducing cardiac output
B) The rescuer is not tilting the head back sufficiently to open the airway
C) The rescuer is using too much force during compressions, causing gastric insufflation
D) The ventilation volume is excessive, leading to airway obstruction
Answer: B
Rationale: In single-rescuer CPR, inadequate head tilt is a common cause of airway obstruction and ineffective
ventilation. (A) affects compressions, not ventilation; (C) and (D) are less common; proper head-tilt chin-lift is
essential for opening the airway.
14 A healthcare provider is called to assess an unresponsive adult. The provider checks for responsiveness,
activates emergency response, and checks breathing and pulse simultaneously. The provider feels a weak
carotid pulse but notes the patient is not breathing normally. What is the immediate next step?
A) Begin high-quality chest compressions at a rate of 100-120/min
B) Provide rescue breathing at a rate of 10-12 breaths/min without compressions
C) Apply an AED and analyze the rhythm
D) Reposition the airway and recheck pulse for up to 10 seconds
Answer: B
Rationale: The patient has a pulse but is not breathing normally, indicating respiratory arrest. The appropriate action
is rescue breathing without compressions. (A) is for cardiac arrest; (C) is for pulseless patients; (D) delays
ventilation unnecessarily.
