BLS — Basic Life Support — All Questions

At what rate should chest compressions be delivered to an adult in cardiac arrest?

• a.60 to 80 compressions per minute
• b.At least 140 compressions per minute
• c.80 to 100 compressions per minute
• d.100 to 120 compressions per minute✓

Current AHA guidelines specify a compression rate of 100 to 120 per minute for all ages. Slower than 100 does not generate adequate perfusion, while faster than 120 shortens the recoil phase so the heart cannot refill, which paradoxically lowers the blood delivered per compression.

What is the correct compression depth for an adult victim?

• a.At least 5 cm, not over 6 cm✓
• b.At least 7.5 cm (3 inches)
• c.About 2.5 cm (1 inch)
• d.As deep as possible

Evidence behind the 2025 AHA Guidelines links survival with depths of at least 5 cm (about 2 inches) and reduced survival with depths over 6 cm (about 2.4 inches).

What is the correct compression depth for an infant (under 1 year)?

• a.About 1 inch (2.5 cm)
• b.One-third of chest depth, about 4 cm✓
• c.About 0.5 inch (1 cm)
• d.At least 2.4 inches (6 cm)

The pediatric chest can be compressed to one-third of its front-to-back depth without organ damage; for an infant that is about 1½ inches (4 cm).

To maximize blood flow during CPR, rescuers should allow complete chest recoil and aim for a chest compression fraction of at least:

• a.30%
• b.60%✓
• c.40%
• d.50%

Chest compression fraction — the proportion of arrest time spent actively compressing — should be at least 60%. Allowing full recoil between compressions lets the heart refill, and minimizing pauses (keeping any interruption under 10 seconds) preserves the coronary and cerebral perfusion that compressions build up.

An AED arrives while you are performing CPR on an adult in cardiac arrest. What should you do?

• a.Turn it on and follow its prompts✓
• b.Wait for a physician to authorize it
• c.Finish 5 more minutes of CPR first
• d.Check a pulse for a full minute first

The AED is used as soon as it arrives, with compressions continuing until the pads are on and pausing only for analysis and the shock.

You are using an AED on a 5-year-old child. Which is correct?

• a.Use pediatric pads or a pediatric dose attenuator if available✓
• b.Never use an AED on a child under 8 years old
• c.Delay defibrillation until EMS brings a pediatric AED
• d.Always use adult pads at full energy regardless of availability

For a child under 8 years, use pediatric pads or a dose attenuator if they are available to reduce the delivered energy. However, if only adult pads are available, use them rather than withhold a needed shock — just ensure the pads do not touch each other. Defibrillation should never be delayed for a shockable rhythm.

Immediately after the AED delivers a shock to an adult, the rescuer should:

• a.Give 2 breaths and reassess the airway
• b.Wait for the AED to re-analyze
• c.Check for a pulse for 10 seconds
• d.Resume compressions immediately✓

Immediate resumption of compressions after a shock shortens the perishock pause; the AED reanalyzes after about 2 minutes.

Before the AED analyzes the rhythm and before delivering a shock, the rescuer must:

• a.Remove the victim's clothing but leave medication patches in place
• b.Ensure no one is touching the victim and clearly state 'Clear'✓
• c.Place both pads on the same side of the chest
• d.Pour water on the chest to improve pad conduction

Everyone must be clear of the victim during analysis and shock so the reading is accurate and no rescuer is shocked; announce 'Clear' and visually confirm no contact. The chest should be dry (not wet), pads are placed in the diagonal positions shown, and any transdermal medication patch is removed and the area wiped so it does not block energy or cause a burn.

Which best describes 'closed-loop communication' during a resuscitation?

• a.The receiver repeats the order back✓
• b.Only the physician may speak
• c.Orders cannot be questioned
• d.Team members write, not speak

AHRQ TeamSTEPPS defines closed-loop communication as using verbal feedback, such as check-backs, to confirm a message was understood; the receiver then reports when the task is done.

During a prolonged resuscitation, how often should the compressor be rotated to maintain high-quality compressions?

• a.About every 2 minutes✓
• b.Every 10 minutes
• c.Only when exhausted
• d.Never, to avoid pauses

Compression depth begins to fall after 90 to 120 seconds, so the 2025 Guidelines consider rotating about every 2 minutes, at the planned rhythm check, sensible.

A team member notices the compressor's rate has slowed below 100 per minute. What is the appropriate action?

• a.Speak up now and suggest a correction✓
• b.Mention it privately after the code
• c.Say nothing to avoid disrespect
• d.Take over without saying anything

Situation monitoring and mutual support mean spotting problems and supporting teammates in the moment; the target rate is 100 to 120 per minute.

How should each breath be delivered during CPR?

• a.Over 5 seconds with maximum volume
• b.As forcefully and quickly as possible
• c.Over about 1 second, to chest rise✓
• d.Only through the nose

Each breath takes about 1 second with just enough volume for visible chest rise; excessive ventilation causes gastric inflation and lowers cardiac output. (2025 terminology uses 'breaths' rather than 'rescue breaths'.)

A single rescuer is performing CPR on an adult without an advanced airway. What compression-to-ventilation ratio is used?

• a.Continuous compressions with no breaths
• b.15 compressions to 2 breaths
• c.30 compressions to 2 breaths✓
• d.5 compressions to 1 breath

A lone rescuer uses a 30:2 ratio for adults, children, and infants. The 15:2 ratio applies only when two rescuers are caring for a child or infant. Once an advanced airway is in place, rescuers switch to continuous compressions with one breath every 6 seconds and stop pausing for breaths.

An adult has a pulse but is not breathing. What is the correct rescue-breathing rate?

• a.1 breath every 2 seconds (about 30 per minute)
• b.1 breath every 6 seconds (about 10 per minute)✓
• c.1 breath every 3 seconds (about 20 per minute)
• d.1 breath every 10 seconds (about 6 per minute)

When an adult has a pulse but inadequate breathing, give rescue breaths at 1 every 6 seconds, about 10 per minute, without chest compressions. Recheck the pulse roughly every 2 minutes. If the pulse is lost, begin CPR with compressions.

A child has a pulse but is not breathing adequately. What is the correct breathing rate?

• a.1 breath every 15 seconds
• b.1 breath every 10 seconds
• c.1 breath every 6 seconds
• d.1 breath every 2–3 seconds✓

For infants and children with a pulse and inadequate breathing, the 2025 Guidelines recommend 20 to 30 breaths per minute, taught as 1 breath every 2 to 3 seconds; every 6 seconds is the adult rate.

A responsive adult clutches his throat, cannot speak or cough, and is turning blue. What should you do?

• a.Give 2 breaths immediately
• b.Encourage him to keep coughing
• c.5 back blows, then 5 abdominal thrusts✓
• d.Perform a blind finger sweep

The 2025 Guidelines recommend cycles of 5 back blows followed by 5 abdominal thrusts for severe adult choking, repeated until the object is expelled or the person becomes unresponsive; encouraging coughing is for mild obstruction.

A 6-month-old infant is choking, cannot cry, and is in obvious distress. The correct technique is:

• a.Abdominal thrusts
• b.5 back blows, then 5 chest thrusts✓
• c.Holding the infant upside down
• d.A blind finger sweep

Infants with severe choking get repeated cycles of 5 back blows and 5 chest thrusts, with the heel of the hand in 2025; abdominal thrusts are not recommended in infants.

A choking victim you were treating suddenly becomes unresponsive. What should you do next?

• a.Keep giving abdominal thrusts
• b.Perform blind finger sweeps
• c.Begin CPR, compressions first✓
• d.Give 5 breaths before anything

Once the person is unconscious, the Guidelines support CPR starting with compressions, which can expel the object; look in the mouth before breaths but avoid blind sweeps.

An adult is coughing forcefully and can still speak while eating. This indicates:

• a.A severe obstruction needing thrusts
• b.A mild obstruction; let him cough✓
• c.A need for immediate back blows
• d.A cardiac arrest requiring CPR

A forceful cough and the ability to speak indicate mild obstruction; coughing generates high airway pressures, and the rescuer watches closely for signs of severe obstruction.

What is the first link in the 2025 Chain of Survival?

• a.Post-cardiac-arrest care
• b.Advanced resuscitation
• c.Recognition and activation✓
• d.Defibrillation

The 2025 single six-link Chain of Survival begins with recognition and emergency activation; prevention and preparedness sit outside the chain.

How many Chains of Survival do the 2025 AHA Guidelines use for adult and pediatric, in- and out-of-hospital arrest?

• a.Four separate chains
• b.One six-link chain✓
• c.Two chains, by setting
• d.Two chains, by age

The 2025 Guidelines consolidated the four chains introduced in 2020 into a single six-link Chain of Survival that applies to all cardiac arrests.

Why is early defibrillation such a critical link in the Chain of Survival for a shockable rhythm?

• a.It matters only in hospitals
• b.Each minute of delay lowers survival✓
• c.It replaces chest compressions
• d.It helps only after 20 minutes

Registry data cited in the 2025 Guidelines show first-shock success falling from 93% within 6 minutes to 75% after 16 minutes, with about a 6% decrease in the probability of survival for each minute of delay.

A rescuer's compressions on an adult measure 3.5 cm deep on a feedback device. What does the evidence behind the 2025 Guidelines say about this depth?

• a.Too shallow; aim for 5 cm or more✓
• b.It is too deep and risks injury
• c.Depth matters only in children
• d.It is ideal for most adults

Survival was better with compression depths of at least 5 cm than with depths under 4 cm, so 3.5 cm is too shallow. Depth also matters in children, where the target is one-third of the chest's depth.

Which pairing correctly lists the adult compression rate and the maximum sensible depth?

• a.60–80 per minute; no more than about 8 cm
• b.100–120 per minute; no more than about 6 cm✓
• c.80–100 per minute; no more than about 4 cm
• d.120–150 per minute; as deep as possible

Adult compressions are given at 100 to 120 per minute, at least 5 cm deep, and excessive depth above 6 cm has been linked with reduced survival. Faster or deeper is not better.

A team's compression fraction in a 15-minute code was 85%. How should this be interpreted?

• a.It means too few breaths were given
• b.It is below the recommended minimum
• c.It shows the compressor pressed too hard
• d.It is above the 60% minimum target✓

The Guidelines describe a 60% chest compression fraction as a minimum target and note that high-performing teams can exceed 80%. A high fraction means pauses were kept short.

During CPR, a rescuer lifts his hands slightly off the chest after each compression. Which component is he protecting?

• a.Rescuer rotation
• b.Compression rate
• c.Breath volume
• d.Full chest recoil✓

Letting the chest re-expand completely increases the blood returning to the heart and the blood flow CPR can produce; leaning on the chest reduces coronary perfusion.

Why do pauses in chest compressions matter so much during CPR?

• a.Pauses cause rib fractures
• b.Coronary perfusion drops at once✓
• c.They make breaths less effective
• d.The AED loses its charge during pauses

The Guidelines note that pauses cause an almost immediate drop in coronary perfusion pressure, which is associated with a lower chance of return of spontaneous circulation.

A patient in cardiac arrest is on a hospital bed with an air mattress. What does the 2025 guidance suggest to improve compression depth?

• a.Use CPR mode or deflate the mattress✓
• b.Compress faster to make up for the softness
• c.Inflate the mattress further
• d.Move the patient to a chair

Compressions on a deflated dynamic mattress, or using the bed manufacturer's CPR mode, can improve compression depth; CPR should be performed on a firm surface whenever possible.

A rescuer kneels on the floor beside an adult in cardiac arrest. Which 2025 positioning principle does this meet?

• a.Patient raised to the rescuer's waist
• b.Rescuer compressing from the patient's feet
• c.Torso at about the rescuer's knee level✓
• d.Rescuer standing above the patient's head

The 2025 Adult BLS top-ten list says compressions should be done with the patient's torso at approximately the level of the rescuer's knees, by kneeling alongside or using a step stool.

A nurse notices depth dropping on the feedback screen after about 2 minutes of compressions. Why is this expected?

• a.The chest becomes stiffer during CPR
• b.Depth declines after 90–120 seconds✓
• c.Rates always rise after 2 minutes
• d.Feedback devices drift after 2 minutes

Compression depth begins to decrease after 90 to 120 seconds of CPR, which is why rotating the compressor about every 2 minutes, at a planned pause, maintains quality.

What is the recommended compression depth for an infant in cardiac arrest?

• a.About 6 cm
• b.Half of the chest depth
• c.About 1 cm
• d.One-third of chest depth, about 4 cm✓

The pediatric chest can be compressed to one-third of its front-to-back diameter without organ damage; for an infant, that is about 1½ inches (4 cm).

Which infant compression technique did the 2025 Guidelines eliminate?

• a.One hand on the lower sternum
• b.The heel of one hand
• c.Two thumbs encircling the chest
• d.Two fingers on the sternum✓

The 2025 Pediatric BLS Guidelines recommend the one-hand or two thumb–encircling hands technique and eliminated two-finger compressions because they failed to reach proper depth.

For children 1 to 8 years old, which compression technique produced greater depth in a registry study?

• a.Two hands✓
• b.Two thumbs
• c.Two fingers
• d.One hand

The 2-hand technique resulted in greater compression depth than the 1-hand technique in children aged 1 to 8, although the 1-hand technique matched target rates better.

An adult in cardiac arrest has severe obesity. What does the 2025 guidance say about technique?

• a.Use standard technique, with more force if needed✓
• b.Use two fingers to avoid injury
• c.Compress only half as deep
• d.Compress more slowly to save energy

CPR for adults with obesity uses the same technique as for other adults; rescuers may need more force to achieve adequate depth and may tire faster.

A hospital is choosing between buying CPR feedback devices and mechanical CPR devices for routine use. Which is recommended for routine use?

• a.Neither device
• b.Mechanical CPR devices
• c.Real-time feedback devices✓
• d.Both equally for every arrest

Real-time feedback devices are recommended to improve manual CPR performance, while routine use of mechanical CPR devices is not recommended because they have not improved survival.

A rescuer's hands have slipped down onto the xiphoid during compressions. What should she do?

• a.Keep going; the xiphoid is ideal
• b.Switch to one-finger compressions
• c.Move up to the lower half of the sternum✓
• d.Move to the upper chest near the neck

Compressions over the lower part of the sternum gave better physiological measures, while hands placed too low may compress over the xiphoid, which may be less effective.

What is the target compression rate for a child in cardiac arrest?

• a.60 to 80 per minute
• b.80 to 100 per minute
• c.140 to 160 per minute
• d.100 to 120 per minute✓

Pediatric data found higher blood pressures with rates of 100 to 120 per minute than with faster rates, and lay teaching uses 100 to 120 for children and infants.

A patient arrests while lying face down after spine surgery, and turning him would badly delay CPR. What is acceptable?

• a.Giving breaths only until turned
• b.Starting CPR in the prone position✓
• c.Starting CPR only after an AED arrives
• d.Waiting until the patient can be turned

Supine CPR is preferred, but rescuers can consider prone CPR if the supine position is not possible or would significantly delay compressions.

Which statement best describes why compression-only CPR by an untrained bystander is still valuable?

• a.It is far better than no CPR at all✓
• b.It replaces the need for an AED
• c.It is required for all children
• d.It is always better than CPR with breaths

A compression-only approach is appropriate for untrained or unwilling lay rescuers, and in children it is superior to no bystander CPR, although CPR with breaths gives better outcomes in children.

A tall 12-year-old boy without signs of puberty collapses. Which compression guidance applies?

• a.Adult guidance: at least 5 cm by age
• b.No compressions until EMS arrives
• c.Child guidance: one-third depth✓
• d.Infant guidance: two thumbs

Child guidelines apply from about 1 year of age until puberty, and signs of puberty — not age alone — move a patient to adult BLS; child compressions are one-third of chest depth.