Safety Training Seminars

BLS Written Test

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Getting ready for your BLS written test? You’re not alone. Thousands of healthcare professionals take this exam every year to earn or renew their Basic Life Support certification from the American Heart Association.

The good news is that the BLS written test isn’t designed to trick you. It’s designed to make sure you understand life-saving techniques well enough to apply them under pressure. That means if you know the core concepts, you’ll do just fine.

This guide walks you through the most common questions you’ll encounter on the BLS written test. We’ve organized them by topic so you can study efficiently and feel confident on test day.

What is the BLS Written Test?

The BLS written test is part of the American Heart Association’s Basic Life Support certification process. It evaluates your knowledge of CPR techniques, AED use, choking relief, and team-based resuscitation.

Most BLS courses follow a blended learning format. You complete an online course that includes videos, practice scenarios, and a written exam. Then you attend an in-person skills session where you demonstrate your abilities on a mannequin.

The written portion typically includes 25 to 35 multiple-choice questions. You need to score at least 84% to pass. The test is open-book during the online course, so you can reference the materials as you go.

CPR Basics: Compressions and Breathing

What is the correct compression-to-ventilation ratio for adult CPR?

Answer: 30 compressions to 2 breaths (30:2)

This ratio applies whether you’re performing CPR alone or with a partner. After every 30 chest compressions, deliver 2 rescue breaths. Each breath should last about 1 second and make the chest rise visibly.

How deep should chest compressions be for an adult?

Answer: At least 2 inches (5 cm) but no more than 2.4 inches (6 cm)

Compressions need to be deep enough to circulate blood effectively. Push hard and push fast. Shallow compressions don’t provide enough blood flow to the brain and vital organs.

What is the correct compression rate for CPR?

Answer: 100 to 120 compressions per minute

This rate applies to victims of all ages—adults, children, and infants. Think of the beat to “Stayin’ Alive” by the Bee Gees. That song hits about 103 beats per minute, which is perfect for keeping your rhythm steady.

Where should you place your hands when performing chest compressions on an adult?

Answer: On the lower half of the breastbone (sternum)

Place the heel of one hand on the center of the chest, then place your other hand on top. Interlock your fingers and keep your arms straight. Position yourself directly over the victim so you can use your body weight to compress the chest.

How long should each rescue breath last?

Answer: About 1 second per breath

Each breath should make the chest rise. If the chest doesn’t rise, reposition the airway and try again. Avoid giving breaths that are too long or too forceful, as this can cause air to enter the stomach.

What should you do if the victim's chest does not rise during rescue breaths?

Answer: Reopen the airway and attempt the breath again

If the chest still doesn’t rise after repositioning, the airway may be blocked. Check for an obstruction and remove it if you can see it. Never perform a blind finger sweep.

AED Use and Safety

When should you use an AED?

Answer: As soon as it is available

Time matters in cardiac arrest. The sooner you deliver a shock, the better the victim’s chances of survival. Don’t wait to start CPR, but use the AED as soon as someone brings it to the scene.

What should you do before delivering a shock with an AED?

Answer: Make sure no one is touching the victim

Say “Clear!” loudly and look to ensure no one is in contact with the victim. This includes you. Touching the victim during a shock can injure you and reduce the shock’s effectiveness.

Can you use an AED on a victim lying in water?

Answer: No, move the victim to a dry area first

Water conducts electricity. Using an AED on someone in a puddle or pool can cause the shock to spread, potentially injuring you or bystanders. Drag the victim to a dry surface before applying the AED pads.

Where should you place AED pads on an adult?

Answer: One pad on the upper right chest, one pad on the lower left side

Follow the diagrams on the AED pads. Place the first pad on the upper right side of the chest, just below the collarbone. Place the second pad on the lower left side of the chest, a few inches below the armpit.

What should you do if the victim has a pacemaker or implanted defibrillator?

Answer: Place the AED pad at least 1 inch away from the device

You’ll usually see a small bulge under the skin where the device is implanted. Avoid placing the pad directly over it. Adjust the pad position if needed, but don’t delay using the AED.

Can you use an AED on a pregnant woman?

Answer: Yes

Cardiac arrest is fatal for both the mother and the baby if not treated immediately. Use the AED just as you would for any other adult. The benefits far outweigh any theoretical risks.

Infant and Child CPR

What is the compression-to-ventilation ratio for infant CPR with two rescuers?

Answer: 15 compressions to 2 breaths (15:2)

This ratio applies when two healthcare providers are performing CPR on an infant. If you’re alone, use the 30:2 ratio instead.

How deep should chest compressions be for a child?

Answer: About 2 inches (5 cm)

For children (age 1 to puberty), compress the chest about 2 inches. For infants (under 1 year), compress about 1.5 inches (4 cm). Let the chest recoil completely between compressions.

How many hands should you use for chest compressions on a child?

Answer: One or two hands, depending on the child’s size

For a small child, one hand may be enough. For larger children, use two hands just like you would for an adult. The goal is to compress the chest adequately without causing injury.

Where do you check for a pulse on an infant?

Answer: Brachial artery (inside of the upper arm)

Place two fingers on the inside of the infant’s upper arm, between the elbow and shoulder. Check for a pulse for no more than 10 seconds. If you don’t feel a pulse or are unsure, start CPR immediately.

What should you do if a child or infant is choking and becomes unconscious?

Answer: Begin CPR and check the airway for obstructions before giving breaths

If the victim becomes unconscious, lower them to the ground and start CPR. Before giving rescue breaths, open the mouth and look for an object. Remove it only if you can see it clearly.

Choking Relief

What is the first step when an adult is choking but still able to cough?

Answer: Encourage them to keep coughing

If the person can cough, speak, or breathe, their airway is only partially blocked. Stay with them and encourage forceful coughing. Don’t interfere unless they can no longer cough or breathe.

What should you do if an adult is choking and cannot cough, speak, or breathe?

Answer: Perform abdominal thrusts (Heimlich maneuver)

Stand behind the person and place your fist just above their navel. Grasp your fist with your other hand and give quick, upward thrusts. Continue until the object is expelled or the person becomes unconscious.

How do you relieve choking in an infant?

Answer: Alternate between 5 back blows and 5 chest thrusts

Support the infant face-down on your forearm with their head lower than their chest. Deliver 5 firm back blows between the shoulder blades. Then turn the infant over and give 5 chest thrusts using two fingers on the breastbone. Repeat until the object comes out or the infant becomes unconscious.

Can you perform abdominal thrusts on a pregnant woman?

Answer: No, perform chest thrusts instead

Abdominal thrusts can harm the baby. Stand behind the pregnant woman and place your hands on the center of her breastbone. Give quick, inward thrusts just as you would with abdominal thrusts, but higher on the chest.

Team Dynamics and Communication

What is the most important factor in successful team resuscitation?

Answer: Clear communication

Team members need to speak clearly, confirm instructions, and update each other on the victim’s status. Closed-loop communication—where you repeat back instructions—reduces errors and keeps everyone coordinated.

What should you do if you notice a team member making a mistake during CPR?

Answer: Speak up immediately in a respectful manner

Patient safety comes first. If you see something wrong, say something right away. Use a calm, respectful tone. For example, “I think the compressions need to be a little deeper.”

What does "minimizing interruptions in chest compressions" mean?

Answer: Pausing compressions for no more than 10 seconds at a time

Every time you stop compressions, blood flow to the brain drops to zero. Limit pauses to essential actions like checking for a pulse, delivering rescue breaths, or analyzing the heart rhythm with an AED.

When should you switch roles during CPR?

Answer: Every 2 minutes or after 5 cycles of 30:2

Fatigue reduces the quality of chest compressions. Switching roles every 2 minutes keeps compressions effective. Make the switch quickly to minimize interruptions.

Special Situations

What should you do if you are alone and witness a child or infant collapse?

Answer: Perform CPR for 2 minutes, then call 911 and get an AED

For children and infants, immediate CPR is the priority. After 2 minutes (about 5 cycles of 30:2), activate the emergency response system and retrieve an AED if available. Then return to CPR.

What should you do if you are alone and witness an adult collapse?

Answer: Call 911 immediately and get an AED, then begin CPR

Adults are more likely to have a cardiac arrest caused by a heart rhythm problem. Early defibrillation with an AED offers the best chance of survival. Activate emergency services first, then start CPR.

Can you stop CPR once you've started?

Answer: Yes, but only under specific conditions

You can stop CPR if: the scene becomes unsafe, the victim shows signs of life (normal breathing, movement), another trained rescuer takes over, you are too exhausted to continue, or a healthcare provider or paramedic assumes care.

What should you do if the victim vomits during CPR?

Answer: Turn the victim’s head to the side, clear the airway, and continue CPR

Roll the victim onto their side if possible, wipe away the vomit, and reposition them on their back. Resume chest compressions immediately. Delaying CPR reduces the victim’s chance of survival.

How to Prepare for the BLS Written Test

Now that you know the most common questions, here’s how to prepare:

Review the American Heart Association guidelines. The BLS course materials cover everything you need. Read through the manual carefully and watch the instructional videos.

Take practice quizzes. Many online BLS courses include practice exams. Take them multiple times until you consistently score above 84%.

Focus on the skills, not just the test. Understanding why you perform each step makes it easier to remember. CPR isn’t about memorizing answers—it’s about saving lives.

Get hands-on practice. The skills session is just as important as the written test. Practice chest compressions, rescue breaths, and AED use on a mannequin until the movements feel natural.

Get Certified with Safety Training Seminars

Ready to earn your BLS certification? We make the process simple, convenient, and affordable.

At Safety Training Seminars, we’re an official American Heart Association Training Center offering BLS, ACLS, PALS, and CPR courses at over 70 locations across California. Our blended learning format lets you complete the online course at your own pace, then attend a brief in-person skills session at one of our convenient offices.

Here’s what sets us apart:

Same-day certification cards. You’ll receive your official American Heart Association card on the day of your skills test. No waiting weeks for it to arrive in the mail.

Lowest price guarantee. We offer the most competitive rates in California, backed by our low price guarantee.
Flexible scheduling. We offer classes every day of the week, including evenings and weekends, so you can find a time that works for you.

Exceptional customer support. Our team is available every day from 8 AM to 10 PM to answer your questions and help you schedule your class.

Whether you’re a nurse, dental assistant, EMT, or any other healthcare professional, we’re here to help you get certified quickly and affordably. Book your BLS class today and join thousands of satisfied students who trust Safety Training Seminars for their certification needs.