Bag-mask ventilation

What it is

Bag-valve-mask (BVM) ventilation gives positive-pressure breaths through a face mask to a patient who is apnoeic or breathing inadequately. The self-inflating bag refills on its own after each squeeze; a one-way valve sends gas to the patient and lets exhaled gas escape, and a reservoir bag connected to high-flow oxygen raises the inspired oxygen fraction close to pure oxygen. It is the core airway skill: it oxygenates patients in cardiac arrest, before intubation and after failed intubation, and buys time in reversible problems such as opioid overdose. Two things make it work: an open airway (head tilt–chin lift or jaw thrust, often with an oral or nasal airway) and a tight mask seal. With one rescuer the mask is held with the C-E grip: thumb and index finger form a «C» pressing the mask down, while the other three fingers form an «E» along the mandible and lift the jaw into the mask. A two-person technique, one holding the mask with both hands and the other squeezing, gives a better seal and is preferred whenever possible. Each breath should be slow and just enough to make the chest rise; large, fast breaths inflate the stomach, cause regurgitation and raise intrathoracic pressure, which reduces venous return. Predictors of difficult mask ventilation should be looked for before sedating any patient.

Indications

• Apnoea or inadequate breathing from any cause: cardiac or respiratory arrest, opioid or sedative overdose, seizures, head injury.
• Hypoxaemia or hypercapnia that needs assisted ventilation while a definitive airway is prepared.
• Pre-oxygenation before intubation, and rescue oxygenation between or after failed intubation attempts.
• Neonatal resuscitation when the newborn is apnoeic or gasping or has a low heart rate.
• Procedural sedation, when the patient stops breathing adequately.

Contraindications and precautions

• No absolute contraindication in an emergency; when it fails, move to a supraglottic device or a definitive airway.
• Full stomach, bowel obstruction or active vomiting: high risk of aspiration; use gentle breaths and suction.
• Facial trauma, beards or no teeth make a seal hard; use two hands, adjuncts or leave dentures in place.
• Complete upper airway obstruction (foreign body, swelling) needs the obstruction treated, not more pressure.
• Suspected cervical spine injury: jaw thrust with in-line stabilisation; base-of-skull fracture: avoid a nasal airway.

Equipment

• Self-inflating bag with one-way valve and reservoir bag, of adult, child or infant size.
• Face masks in several sizes; a mask should cover from the bridge of the nose to the cleft of the chin.
• Oxygen source and tubing at high flow to the reservoir.
• Oral and nasal airways, working suction, and a PEEP valve if available.
• Pulse oximeter and, ideally, waveform capnography.

Step by step (and why)

1. Call for help, connect oxygen to the bag and fill the reservoir — the reservoir is what gives a high oxygen fraction.
2. Choose a mask from the bridge of the nose to the chin cleft, not over the eyes — the right size seals without pressing on the eyes.
3. Position the head (sniffing position if no neck injury; ear level with the sternum) — this aligns and opens the upper airway.
4. Suction the mouth and insert an oral or nasal airway — adjuncts keep the tongue off the pharynx during ventilation.
5. Seal with the C-E grip, lifting the jaw into the mask rather than pushing the mask onto the face — pushing closes the airway.
6. With two rescuers, one holds the mask with both hands and lifts the jaw while the other squeezes — the seal is better.
7. Squeeze slowly over about 1 second until the chest rises, then let it fall fully — small slow breaths keep air out of the stomach.
8. Give breaths at the right rate (30:2 in CPR, one every 6 seconds with a pulse) — overventilation lowers venous return.
9. Watch chest rise, saturation and capnography; if poor, reposition, use two hands or add an adjunct — then escalate.

Complications

• Gastric insufflation, leading to regurgitation, aspiration and splinting of the diaphragm.
• Hypoventilation and hypoxaemia from a leaking seal or an obstructed airway.
• Barotrauma and pneumothorax from high pressures, especially in children and stiff lungs.
• Hypotension from hyperventilation and high intrathoracic pressure, which lower venous return.
• Pressure injury to the eyes, nose and face, and cervical spine movement in trauma.

Next step

• If ventilation is still poor after optimising the airway and seal, call the senior airway clinician and move to a supraglottic device.
• Plan a definitive airway (intubation) when the cause will not reverse quickly or the airway cannot be protected.
• Decompress the stomach with an orogastric or nasogastric tube if it has filled with air.
• Treat the cause: naloxone for opioid toxicity, glucose for hypoglycaemia, the arrest algorithm in cardiac arrest.
• Record the difficulty of mask ventilation and tell the team, because it matters for future anaesthesia.

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Elsewhere in DurgiPedia

• Basic life support from the nursing side
• Oxygen therapy: devices, flows and safety
• Dead space and alveolar ventilation

Connections

← All clinical skills

Educational content; it does not replace supervised hands-on training, your institution's protocols or a prescriber's order. A procedure is learnt with a teacher and done only once you are trained to do it.

Sources: Bag-Valve-Mask Ventilation (StatPearls (NCBI Bookshelf), 2025).

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Representative model, for educational purposes only.