Ever walked into a BLS refresher and felt the questions were written by a robot?
But you stare at “What is the compression depth? ” and suddenly wonder if you ever really learned it or just memorized a line from a PowerPoint.
No fluff here — just what actually works Easy to understand, harder to ignore..
If you’ve ever crammed for the basic life support exam, you know the pressure: a ticking clock, a stack of multiple‑choice items, and that nagging fear you’ll miss the one detail that decides whether you pass. The good news? Most of those questions aren’t trick puzzles—they’re testing concepts you already use when you’re actually saving a life.
Below you’ll find the most common exam questions, why they’re asked, and the answers you need to keep in mind. Think of this as a cheat‑sheet you can actually use, not just a list of facts you’ll forget the moment the test ends.
What Is Basic Life Support
Basic Life Support (BLS) is the set of lifesaving techniques you perform when someone’s heart or breathing stops. It’s the “first line” before advanced providers take over. In practice, it means chest compressions, rescue breaths, and using an automated external defibrillator (AED) when it’s available Turns out it matters..
You don’t need a fancy degree to deliver BLS—just a solid grasp of the chain of survival and the ability to act quickly. The exam tests that you know the how and the why behind each step, not just the steps themselves.
Core components
- Chest compressions – 100‑120 per minute, at least 2 inches deep for adults.
- Rescue breaths – 1 breath every 6 seconds after 30 compressions (adult) or 15 compressions (infant).
- AED use – turn on, attach pads, follow voice prompts, and deliver shock if advised.
- Team dynamics – clear communication, role assignment, and minimizing interruptions.
Why It Matters / Why People Care
You might ask, “Why does a multiple‑choice question about compression depth matter?” Because when you’re on the floor with a victim, that depth makes the difference between a perfused brain and irreversible damage.
People who skip BLS training think it’s “just for EMTs.In practice, ” Turns out, anyone who might be first on the scene—teachers, coaches, office workers—needs the same knowledge. The exam is the gatekeeper that ensures the training sticks Still holds up..
When you understand the reasoning behind each question, you remember it longer. To give you an idea, the “hands‑over‑hands” technique isn’t a random hand‑position; it maximizes force transfer while keeping your shoulders over your hands, reducing fatigue.
How It Works (or How to Do It)
Below is the meat of the exam—what you’ll actually see on the test and how to nail each answer.
1. Compression Rate and Depth
Typical question:
What is the recommended compression rate for adult BLS?
Answer: 100‑120 compressions per minute Less friction, more output..
Why: This range keeps coronary perfusion pressure high enough to push blood to the brain. Anything slower drops the pressure; faster and you lose depth Worth keeping that in mind..
Tip for the exam: Remember the “100‑120” mantra and associate it with the “pop‑rock” song “Stayin’ Alive” (103 BPM). If the answer choices include 80, 100, 130, and 150, the 100‑120 range is the only one that fits But it adds up..
2. Hand Placement
Typical question:
Where should you place your hands for adult chest compressions?
Answer: Center of the chest, on the lower half of the sternum.
Why: This avoids the xiphoid process (the tip of the sternum) which can fracture and damage internal organs.
Exam clue: If an answer mentions “mid‑sternum” or “lower half of the sternum,” that’s the one. “Upper half” is a trap.
3. Compression Depth
Typical question:
What is the minimum compression depth for an adult victim?
Answer: At least 2 inches (5 cm) That's the whole idea..
Why: Anything shallower won’t generate enough pressure to circulate blood.
Pro tip: For infants, the depth drops to about 1.5 inches (4 cm), and for children it’s roughly 2 inches as well, but you’ll see “one‑third the chest depth” as an answer choice—pick that if it’s an option.
4. Rescue Breaths
Typical question:
After how many compressions should you give rescue breaths to an adult?
Answer: After 30 compressions.
Why: The 30:2 ratio balances oxygen delivery with circulation.
Gotcha: For infants and children, the ratio changes to 15:2 if you have two rescuers. If the question specifies “single rescuer,” stick with 30:2 Practical, not theoretical..
5. AED Pad Placement
Typical question:
Where do you place the AED pads on an adult?
Answer: One pad on the upper right chest (just below the clavicle) and the other on the lower left side (below the armpit, over the heart).
Why: This creates a current pathway through the heart.
Memory aid: “Right‑upper, left‑lower” – think of a diagonal line across the torso It's one of those things that adds up..
6. Cycle Timing
Typical question:
How long should you pause for rhythm analysis on an AED?
Answer: No more than 10 seconds.
Why: Every second you stop compressions reduces coronary perfusion.
Exam trick: Some answers say “15 seconds” or “30 seconds.” The correct one is the shortest, because the algorithm is built to minimize interruptions.
7. Team Dynamics
Typical question:
What is the most important role of the second rescuer during BLS?
Answer: Rotate compressions every two minutes to prevent fatigue.
Why: Fatigued rescuers compress at lower depth and rate, compromising effectiveness It's one of those things that adds up. Simple as that..
Quick recall: “Switch every two” – you’ll spot it in any answer list that mentions “rotate” or “swap roles.”
8. Special Situations – Pregnancy
Typical question:
When performing BLS on a pregnant woman in the third trimester, where should you place your hands for compressions?
Answer: Slightly higher than usual—on the sternum, but you may need to push up on the uterus (uterine displacement) to relieve pressure on the inferior vena cava.
Why: The growing uterus can compress the great veins, reducing return to the heart Easy to understand, harder to ignore..
Exam note: If the answer mentions “tilt the patient 30 degrees left” that’s for choking, not BLS. Look for “uterine displacement” or “higher hand placement.”
9. BLS for Infants
Typical question:
What is the correct compression technique for an infant?
Answer: Two fingers placed just below the nipple line, compressing 1.5 inches (or one‑third the chest depth) Practical, not theoretical..
Why: Infants have a fragile rib cage; using two fingers avoids injury Not complicated — just consistent..
Mnemonic: “Two‑finger, one‑third” – you’ll spot it quickly That alone is useful..
10. Oxygen Use
Typical question:
When should supplemental oxygen be administered during BLS?
Answer: As soon as an airway is secured (e.g., with a bag‑valve‑mask) and a pulse oximeter shows SpO₂ < 94%.
Why: High‑flow oxygen improves tissue oxygenation while you’re still providing chest compressions.
Exam shortcut: If the answer says “immediately after the first shock” that’s for advanced cardiac life support (ACLS), not BLS.
Common Mistakes / What Most People Get Wrong
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Counting off wrong – Many candidates start the count at “one” after each pause, forgetting they need a continuous rhythm. The exam often throws a “What’s the correct total number of compressions after 2 minutes?” question; the answer is 120–144, depending on the exact rate Most people skip this — try not to..
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Mixing adult and infant ratios – It’s easy to slip a 15:2 ratio into an adult scenario. The test will deliberately pair “single rescuer” with “adult” to catch you.
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Ignoring the “no pulse” cue – Some questions describe a patient with agonal breathing but no pulse. The correct move is to start CPR immediately, not to give rescue breaths only.
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Over‑relying on the AED voice prompts – The exam sometimes asks what you do if the AED says “no shock advised.” The answer: resume CPR immediately, don’t waste time checking the rhythm again That alone is useful..
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Hand placement on the ribs – A common trap is “mid‑rib” versus “sternum.” The correct spot is always the sternum; the ribs are a no‑go.
Practical Tips / What Actually Works
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Use a metronome or song – “Stayin’ Alive” (103 BPM) or “Crazy in Love” (120 BPM) keep you in the 100‑120 window.
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Practice the “two‑minute switch” – Set a timer on your phone. When it buzzes, swap roles without stopping compressions.
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Visualize the AED diagram – Before the exam, draw a quick sketch of the pad placement. The act of drawing cements the memory.
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Chunk the steps – Think of BLS as three blocks: Compress, Breath, Defibrillate. When a question lists a sequence, the correct answer will follow that order.
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Teach it to someone else – Explaining the steps to a friend forces you to re‑phrase the concepts, which sticks better than rote memorization Most people skip this — try not to..
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Read the question stem carefully – Look for keywords like “single rescuer,” “infant,” or “third‑trimester.” Those modifiers change the answer entirely.
FAQ
Q: How many compressions should I give before checking the pulse?
A: For adults, give 30 compressions, then pause to check the pulse (no more than 10 seconds). If no pulse, continue CPR Not complicated — just consistent..
Q: Can I use a pocket‑size AED on a child?
A: Yes, most modern AEDs have pediatric pads or a pediatric setting. If not, use adult pads and follow the device’s instructions Easy to understand, harder to ignore..
Q: What if I’m alone with an infant?
A: Perform 30 compressions followed by 2 breaths, just like adult BLS, because you have no one to help you rotate.
Q: Is it okay to give rescue breaths with a mask?
A: Absolutely. A bag‑valve‑mask (BVM) or a pocket mask with a one‑way valve is preferred to reduce infection risk No workaround needed..
Q: Do I need to stop compressions to place the AED pads?
A: No. You can place the pads while continuing compressions; pause only when the AED prompts you to analyze the rhythm Not complicated — just consistent..
Wrapping it up
The basic life support exam isn’t a trick quiz; it’s a sanity check to make sure you can translate training into action when seconds count. By focusing on the why behind each answer, you’ll remember the details long after the test is over—and more importantly, you’ll be ready to save a life No workaround needed..
So next time you see a question about compression depth, picture your hands on a manikin, feel the resistance, and let the rhythm guide you. That’s the real test, not the multiple‑choice sheet. Good luck, and keep practicing—you’ve got this Turns out it matters..
