Guide — Clinical Skills
Manual Resuscitation with a Bag-Valve-Mask
The bag-valve-mask is the most basic life-support tool and the easiest to use badly. This guide covers self-inflating versus flow-inflating bags, the mask seal that decides everything, the oxygen reservoir, and why over-ventilation does real harm.
7 min read · Clinical Skills
Written by Apex Respiratory Editorial Team
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Overview
A bag-valve-mask (BVM, manual resuscitator) delivers positive-pressure ventilation by hand. It is the most widely used airway device in emergencies and the starting point for any resuscitation before or after advanced airway placement.
Two bag types exist. The self-inflating bag refills on its own after each squeeze and works without a gas source — making it the resuscitation standard. The flow-inflating (anesthesia) bag needs a continuous gas source to stay inflated but lets the operator feel compliance and deliver CPAP. Because it fails when the gas supply fails, it is not used for emergency resuscitation outside of an anesthesia context.
Key Concepts
- Components. A complete BVM assembly includes a self-inflating bag, a non-rebreathing valve, a mask, an oxygen reservoir, and an oxygen inlet. The non-rebreathing valve ensures unidirectional flow and prevents exhaled gas from re-entering the bag.
- FiO₂ and the reservoir.With a reservoir and high flow (10–15 L/min), a self-inflating bag delivers close to 100% FiO₂. Without a reservoir it entrains room air during refill and delivers only about 40–60% FiO₂ — inadequate for critically ill patients.
- E-C clamp mask seal.Thumb and index finger form a “C” on the mask body while the remaining three fingers form an “E” lifting the jaw up into the mask. A two-person technique — one provider seals with both hands, the other squeezes — achieves a far better seal and more consistent tidal volumes.
- Adult ventilation targets.Deliver just enough volume for visible chest rise (approximately 500–600 mL, roughly 6–7 mL/kg) at 10–12 breaths/min for an apneic adult with a pulse. During CPR with an advanced airway, deliver about 1 breath every 6 seconds (10/min). Squeeze smoothly rather than forcing a rapid bolus.
- PEEP valve. A PEEP valve can be attached to the exhalation port to maintain end-expiratory pressure in PEEP-dependent patients (for example, during transport of a patient coming off mechanical ventilation).
BVM Components at a Glance
| Component | Function |
|---|---|
| Self-inflating bag | Refills independently after each squeeze; works without a gas source; standard for emergency use. |
| Non-rebreathing valve | Prevents exhaled gas from re-entering the bag; ensures unidirectional flow to the patient. |
| Mask | Transparent, cushioned interface that creates a seal over the nose and mouth. |
| Oxygen reservoir | Prevents room-air entrainment during bag refill; required to deliver near-100% FiO₂. |
| Oxygen inlet | Connection point for the supplemental O₂ supply; flow set to 10–15 L/min with reservoir. |
| PEEP valve (optional) | Attached to the exhalation port; maintains end-expiratory pressure in PEEP-dependent patients. |
Assessment & Findings
During BVM ventilation, continuously evaluate the following:
- Visible chest rise.Each squeeze should produce bilateral, symmetric chest rise — the primary real-time indicator of effective ventilation. Asymmetric or absent rise signals a mask leak, airway obstruction, or incorrect tube placement.
- SpO₂ and waveform capnography. Monitor SpO₂ continuously. When available, waveform ETCO₂ confirms ventilation is reaching the lungs and helps titrate rate to avoid hypocapnia from over-ventilation.
- Gastric distention.A visibly distended abdomen is a warning sign of air entering the stomach rather than the lungs — caused by over-ventilation, poor airway positioning, or mask leak. Reposition the head, reassess the seal, and slow the rate.
- Mask seal integrity. Listen and feel for air escaping around the mask. An audible leak confirms inadequate seal; adjust finger position or switch to two-person technique.
RT Priorities & Interventions
- Secure a good mask seal first. Use the E-C clamp and switch to two-person technique whenever possible. No ventilation is effective without an airtight seal.
- Attach the oxygen reservoir and set high flow.Connect the reservoir bag before use and set the oxygen flow to 10–15 L/min to ensure near-100% FiO₂.
- Ventilate to visible chest rise only.Squeeze just enough for bilateral rise, targeting approximately 500–600 mL per breath. Avoid forcing large or fast volumes.
- Maintain the correct rate.Apneic adult with a pulse: 10–12 breaths/min. CPR with advanced airway: 10 breaths/min (1 breath every 6 seconds). Resist the instinct to ventilate faster under stress.
- Apply a PEEP valve when indicated. Patients who were on PEEP before transport or resuscitation should have a PEEP valve attached to prevent derecruitment.
- Monitor and document. Record SpO₂, waveform ETCO₂ when available, rate, and any signs of gastric distention or seal failure.
Common Pitfalls
Over-ventilation (the most dangerous pitfall).Squeezing too fast or too hard raises intrathoracic pressure, reduces venous return, and lowers cardiac output — critically harmful during CPR. It also forces air into the stomach, raising aspiration risk. Ventilate to chest rise only; stay at 10–12 breaths/min.
- Inadequate mask seal. A one-handed grip on a difficult face will leak. Switch to two-person technique early rather than persisting with an ineffective single-provider seal.
- Missing the oxygen reservoir.Assembling or using the BVM without a reservoir drops FiO₂ to 40–60%. Always confirm the reservoir is attached before use.
- Ignoring a PEEP requirement. Patients with hypoxemic respiratory failure may be PEEP-dependent. Bagging without a PEEP valve can cause rapid derecruitment and worsening hypoxemia.
- Poor head positioning.Failure to achieve a patent airway with head-tilt–chin-lift (or jaw thrust in trauma) renders even excellent BVM technique ineffective. Airway positioning precedes ventilation.
Board Exam Pearls
- A self-inflating bag works without a gas source; a flow-inflating (anesthesia) bag does not — it collapses without a continuous gas supply.
- A reservoir plus 10–15 L/min O₂is required to deliver close to 100% FiO₂; without a reservoir expect only 40–60%.
- Avoid hyperventilation— it lowers cardiac output (reduces venous return) and causes gastric insufflation. Ventilate to visible chest rise only.
- Two-person BVM techniquegives a superior seal; target 10–12 breaths/min for an apneic adult with a pulse, and 10/min during CPR with an advanced airway.
- Gastric distentionduring BVM is a sign of over-ventilation or poor airway positioning — not a normal finding.
FAQ
What is the difference between a self-inflating and a flow-inflating bag?
A self-inflating bag refills on its own after each squeeze and works without any gas source — making it the standard choice for emergency resuscitation. A flow-inflating (anesthesia) bag requires a continuous gas source to stay inflated, but allows the operator to feel patient compliance and deliver CPAP. If no gas source is available, only the self-inflating bag will work.
How do I get close to 100% FiO₂ with a self-inflating BVM?
Attach an oxygen reservoir to the bag and set the oxygen flow to 10–15 L/min. Without a reservoir, the self-inflating bag entrains room air during refill, delivering only about 40–60% FiO₂. The reservoir prevents that entrainment and allows near-100% FiO₂ delivery.
Why is over-ventilation harmful during BVM resuscitation?
Ventilating too fast or with too much volume raises intrathoracic pressure, which reduces venous return to the heart and lowers cardiac output — a critical problem during CPR. It also forces air into the stomach (gastric insufflation), raising the risk of regurgitation and aspiration. Barotrauma is an additional risk. Ventilate only to visible chest rise and avoid rates faster than 10–12 breaths per minute.
When should I use a two-person BVM technique instead of one person?
Whenever possible. One person can rarely maintain an adequate mask seal while also squeezing the bag, especially in patients with facial hair, edentulous faces, or abnormal anatomy. With two people, one provider uses both hands to hold the mask with the E-C clamp on both sides, while the other squeezes the bag — yielding a far better seal and more consistent tidal volumes.
Put it to work
Rate times tidal volume is the minute ventilation you are delivering by hand. Check whether your bagging matches the target.
Open the Minute Ventilation calculator →Related Resources
Sources
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021. Emergency cardiovascular life support and airway management.
- Cairo JM. Mosby's Respiratory Care Equipment. 11th ed. Elsevier; 2022. Manual resuscitators.