4 Ventilation Support

Ventilation and oxygenation

Ventilation moves air into and out of the lungs, bringing oxygen to the alveoli and removing carbon dioxide. Oxygenation describes oxygen entering the blood, whereas ventilation describes air movement and carbon-dioxide removal. Supplemental oxygen can improve oxygenation, but it does not replace effective breaths when breathing is absent or inadequate.

Positive-pressure ventilation with a bag-mask device (BVM) supports a person who is not breathing or whose breathing is ineffective. Give breaths slowly and use only enough volume to produce visible chest rise. Excessive or rapid breaths can inflate the stomach, cause regurgitation and aspiration, injure the lungs, and, during cardiac arrest, reduce blood flow by raising pressure in the chest.

Choose the appropriate breath timing

For an adult with a pulse who is in respiratory arrest, current AHA guidance considers one breath every $6$ seconds, or $10$ breaths per minute, reasonable. If an adult is in cardiac arrest and has no advanced airway, follow the CPR compression-to-ventilation protocol, commonly $30$ compressions to $2$ breaths, rather than using the respiratory-arrest rate.

Pediatric ventilation rates and CPR procedures differ. Follow current pediatric guidance and local protocol.

Prepare for bag-mask ventilation

BVM ventilation is a practiced clinical skill. Use appropriate protective equipment, summon emergency help, and follow training and local protocols. When possible, use two trained rescuers: one opens the airway and holds a two-handed mask seal, while the other squeezes the bag. This often works better than trying to hold the seal and ventilate with one hand.

Deliver controlled breaths

1. Position and open the airway. Place the patient supine if appropriate. If neck injury is not suspected, use a head-tilt–chin-lift. If cervical-spine injury is suspected, minimize neck movement and use a jaw thrust when trained. An airway adjunct may help when indicated and appropriately sized.

2. Choose and place the mask. Select a mask that covers the nose and mouth without covering the eyes. Center it over the bridge of the nose and chin.

3. Seal and lift the jaw. With two rescuers, use both hands to press the mask into a seal while lifting the bony jaw toward it. Avoid pushing on the soft tissue beneath the chin, which can obstruct the airway.

4. Give a controlled breath. Squeeze the bag smoothly, typically over about $1$ second, until the chest visibly rises. Release fully to allow exhalation, and let the chest fall before the next breath. Add supplemental oxygen when available and when trained to use it.

5. Reassess continuously. Watch chest rise and fall, check for mask leaks, and assess the patient’s overall response. Do not force the bag or squeeze it rapidly.

Monitor ventilation

Use several signs together because no single measure is sufficient.

• Chest movement: Look for visible, symmetrical rise with each breath and fall during exhalation. This is a practical immediate check.

• Air entry: When appropriate and feasible, listen for breath sounds on both sides. Asymmetrical or absent sounds warrant reassessment and escalation.

• Pulse oximetry (SpO₂): This tracks blood oxygen saturation, not ventilation itself. Readings may lag behind breathing changes and can be unreliable with poor circulation.

• Waveform capnography (EtCO₂): When available, this provides breath-by-breath evidence of exhaled carbon dioxide and helps assess ventilation trends. Interpret the waveform and value in clinical context.

• Overall status: Reassess breathing effort, skin color, level of responsiveness, and pulse as appropriate. If effective ventilation cannot be achieved, seek advanced airway support without delay.

Troubleshoot ineffective ventilation

When ventilation is difficult, correct the likely cause rather than increasing force. Frequent causes include a poor mask seal, soft-tissue or foreign-body obstruction, absent teeth, and snoring caused by airway blockage.

• Little or no chest rise: The mask seal may be poor, the airway may be blocked or poorly positioned, or there may be an obstruction. Reposition the head and jaw, reseat the mask, use a two-person, two-hand seal, and check for visible obstruction. Suction if trained and equipped.

• Air leaking around the mask: The mask may be the wrong size or fit poorly; facial hair, injury, or shape may interfere. Reposition or change the mask, lift the jaw into it, and use two rescuers if available.

• Air does not enter easily: Possible causes include obstruction, poor alignment, an inadequate seal, or reduced lung compliance. Recheck airway position and seal, inspect for obstruction, and promptly escalate if ventilation remains difficult.

• Stomach visibly distends or regurgitation occurs: Breaths may be too forceful, too large, or too rapid, allowing air into the stomach. Reduce volume and pressure, slow delivery, allow full exhalation, and reassess the seal and airway. Manage regurgitation according to training and protocol.

• SpO₂ stays low or the EtCO₂ waveform is absent or abnormal: Ventilation may be ineffective, oxygen supply may be inadequate, or the patient may have a serious underlying problem. Recheck connections, oxygen supply, airway position, seal, and chest movement; reassess and call for advanced help. Do not rely on a single monitor reading.

Persistent difficulty requires prompt reassessment and escalation rather than increasingly forceful bagging.

Apply the core principles

Effective BVM support depends on an open airway, a reliable mask seal, and slow breaths just large enough to produce visible chest rise. For an adult with a pulse in respiratory arrest, give one breath every $6$ seconds; during cardiac arrest without an advanced airway, follow the CPR compression-to-ventilation protocol. Monitor chest movement and the patient’s response, using pulse oximetry and capnography when available. If ventilation is ineffective, correct positioning and seal problems and escalate promptly.