2.4 Ventilation and Bag-Mask Basics
Key Takeaways
- Give enough breath to make the chest rise; excessive ventilation can reduce venous return and worsen outcomes.
- For CPR without an advanced airway, cycles are organized around compressions and breaths.
- Bag-mask ventilation works best with a good seal, airway positioning, and two rescuers when available.
- Once an advanced airway is in place during adult arrest, compressions become continuous with ventilations about every 6 seconds.
2.4 Ventilation and Bag-Mask Basics
Ventilation questions test airway positioning, visible chest rise, bag-mask technique, and avoidance of hyperventilation. The best rescuer ventilates just enough and protects compression quality.
Current official baseline
The adult BLS guidance covers recognition of cardiac arrest, emergency response activation, high-quality CPR, AED use, adult foreign-body airway obstruction, and opioid antagonist integration. Use the official AHA 2025 Adult Basic Life Support Guidelines page when your course materials or training-center instructions differ from third-party summaries: AHA 2025 Adult Basic Life Support Guidelines.
What you need to know
| Decision point | What to do |
|---|---|
| Airway position | Use head tilt-chin lift unless trauma is suspected; use jaw thrust when spinal injury is a concern and you are trained to do so. |
| Breath volume | Ventilate until the chest rises. More volume is not better and can increase gastric inflation. |
| Bag-mask skill | Use a C-E seal, lift the jaw into the mask, and use two rescuers when available for better seal and ventilation control. |
| Advanced airway | With an advanced airway in adult cardiac arrest, avoid stopping compressions for breaths; deliver about 10 breaths per minute. |
How this shows up on BLS/ACLS questions
BLS and ACLS items usually test priority. Read the patient state first: age, pulse status, breathing status, rhythm, stability, and number of rescuers. Then choose the action that protects perfusion, oxygenation, defibrillation timing, or the correct algorithm branch. If an answer sounds advanced but delays CPR, shock delivery, ventilation, or an urgent stability intervention, it is usually a distractor.
Scenario anchor
During two-rescuer CPR, the chest does not rise with breaths. The next move is to reposition the airway and improve the mask seal before assuming the lungs are impossible to ventilate.
Common traps
- Hyperventilating because the patient looks cyanotic.
- Stopping compressions too long to place an airway.
- Squeezing the bag hard instead of watching for chest rise.
Study action
Write this section as a one-line rule in your own words, then test it with mixed questions from the BLS/ACLS practice bank. Do not review only the matching topic. Mix it with nearby branches so you can tell when the rule applies and when it does not. For example, compare respiratory arrest with a pulse against pulseless arrest, or compare unstable tachycardia against VF/pVT arrest. The exam rewards that discrimination more than memorizing isolated facts.
For an infant (under 1 year of age), what is the recommended technique for performing chest compressions when a single rescuer is present?
When 2 healthcare providers perform CPR on a child (1 year to puberty), what is the correct compression-to-ventilation ratio?