When is bag‑mask ventilation indicated and how should it be performed correctly in emergency situations?

Bag-Mask Ventilation in Emergency Situations

Bag-mask ventilation (BMV) is indicated for any patient requiring ventilatory support who lacks a patent airway or adequate spontaneous breathing, and should be performed using a two-person technique with proper airway positioning, appropriate tidal volumes (500-600 mL delivered over 1 second to produce visible chest rise), and avoidance of excessive ventilation. 1, 2

Primary Indications for Bag-Mask Ventilation

BMV is indicated in the following emergency situations:

• Cardiac arrest - as an acceptable alternative to advanced airway placement during CPR 1
• Respiratory failure or apnea - when patients cannot maintain adequate oxygenation/ventilation 3
• Bridge to intubation - maintaining oxygenation during the apneic period after induction, particularly when intubation is delayed or difficult 4
• Failed or unsuccessful intubation - when endotracheal tube placement is not possible 1
• Pre-oxygenation maintenance - as BMV results in higher oxygen saturation (96% vs 92%) compared to apneic oxygenation alone 4

Correct Performance Technique

Personnel Requirements

BMV should be performed by two trained providers whenever possible, as this is significantly more effective than single-rescuer technique. 1, 5

• Two-person technique (strongly preferred): One rescuer uses both hands to maintain jaw thrust and tight mask seal while the second compresses the bag 1, 2
• Single-person technique is NOT recommended during CPR; lone rescuers should use mouth-to-barrier device ventilation instead 1
• Both rescuers must observe chest rise to confirm adequate ventilation 1

Equipment Selection

• Bag size: Use 450-500 mL minimum for infants/children; 1000 mL (adult bag) for adolescents/adults 1
• Oxygen delivery: Attach oxygen reservoir to deliver 60-95% FiO2 with flow rates of 10-15 L/min 1, 2
• Mask fit: Select appropriate mask size to create tight seal 1

Airway Management Steps

1. Open the airway using head tilt-chin lift or jaw thrust maneuver 1
2. Position the mask with tight seal by lifting jaw toward mask (not pushing mask down) 1
3. Insert airway adjuncts as needed:
   • Oropharyngeal airways for unconscious patients without gag reflex 1
   • Nasopharyngeal airways for patients with clenched jaw or when oral airway cannot be placed (avoid in basilar skull fracture) 1

Ventilation Parameters

Critical technical specifications:

• Tidal volume: 500-600 mL (6-7 mL/kg) - deliver only enough to produce visible chest rise 1, 2
• Inspiratory time: 1 second per breath 1, 2
• During CPR without advanced airway: Give 2 breaths during 3-4 second pause after every 30 compressions 1, 2
• With advanced airway in place: 1 breath every 6 seconds (10 breaths/minute) with continuous compressions 2

Critical Pitfalls to Avoid

Excessive Ventilation (Class III - Harm)

Hyperventilation is explicitly harmful and must be avoided. 1, 2

Excessive ventilation causes:

• Increased intrathoracic pressure reducing venous return and cardiac output 1
• Decreased cerebral and coronary blood flow 1
• Air trapping and barotrauma in patients with airway obstruction 1
• Increased aspiration risk 1

Gastric Insufflation

Minimize gastric inflation by: 1

• Delivering breaths slowly over 1 second (not rapid/forceful) 1
• Using only enough pressure to achieve visible chest rise 1
• Considering cricoid pressure in unresponsive patients (though NOT routinely recommended in cardiac arrest - Class III) 1
• Placing nasogastric/orogastric tube if ventilation becomes compromised 1

Technical Errors

• Inadequate mask seal - leads to air leak and ineffective ventilation; use two-handed technique 1, 3
• Incorrect airway positioning - tongue obstruction is common; ensure proper head tilt-chin lift 1, 3
• Single-provider BMV during CPR - less effective than mouth-to-barrier device for lone rescuer 1

Special Considerations

Difficult Bag-Mask Ventilation

When BMV is difficult or impossible: 3

• Optimize head/neck positioning 1
• Use two-person technique with both hands securing mask 1
• Insert oropharyngeal or nasopharyngeal airway 1
• Consider supraglottic airway device if BMV fails 1
• Prepare for immediate advanced airway if unable to ventilate 3

Pediatric Considerations

In pediatric out-of-hospital cardiac arrest, it is reasonable to continue BMV rather than attempting advanced airway placement. 1

• Most pediatric arrests are respiratory in origin, making ventilation critically important 1
• Use appropriate pediatric bag size (450-500 mL minimum) 1
• Same principles apply: avoid excessive ventilation, ensure chest rise 1

COVID-19 and Infectious Precautions

In high-risk infectious scenarios: 1

• Use closed circuit systems (anesthetic circle) preferred over open bag-mask 1
• Place HME filter between catheter mount and circuit 1
• Ensure tight mask seal to minimize aerosolization 1
• Two-person technique with VE-grip recommended for obese patients 1

Comparison to Advanced Airways

While BMV is acceptable during CPR, providers must understand the trade-offs: 1

• Advantages: Can be performed without interrupting compressions (when done by two providers), requires less training than intubation 1
• Disadvantages: Higher aspiration risk, requires compression pauses if only one provider available, gastric insufflation risk 1, 6
• Evidence: A 2018 RCT showed BMV failed to demonstrate noninferiority to ETI for neurological outcomes (4.3% vs 4.2% favorable outcome), though BMV had higher complication rates including regurgitation (15.2% vs 7.5%) 6

The decision to place an advanced airway should weigh the need for minimally interrupted compressions against risks of airway placement attempts. 1