Ventilation during cardiopulmonary resuscitation (CPR) delivers oxygen to the lungs and removes carbon dioxide, supporting the circulation generated by chest compressions. Professional rescuers often use a Bag-Valve Mask (BVM)—a self-inflating bag attached to a face mask—to provide these rescue breaths. How often the bag should be squeezed depends entirely on the specific resuscitation scenario and whether chest compressions must be paused. Precise timing and technique are necessary to ensure effective oxygen delivery while minimizing complications like air entering the stomach or hyperventilation.
Standard Ventilation Timing During Interrupted Chest Compressions
In the most common CPR scenario, where an advanced airway has not been secured, chest compressions must be temporarily halted to allow ventilation. Current guidelines for adult CPR recommend a compression-to-ventilation ratio of 30:2, whether performed by one or two rescuers. This means the rescuer performs 30 high-quality chest compressions and then pauses briefly to deliver two breaths using the bag-mask device.
The interruption should be as short as possible to maintain blood flow, ideally limiting the pause to less than ten seconds for the two breaths. Each squeeze of the bag should be delivered over approximately one second. For pediatric patients (infants and children), the ratio often changes to 15 compressions followed by two breaths when two trained rescuers are present.
The rescuer must focus on minimizing the “hands-off” time, as pauses in compressions significantly reduce the pressure needed to perfuse the heart and brain. Delivering the two breaths in quick succession, each lasting one second, achieves the balance between oxygenation and preserving continuous circulation.
Ventilation Timing with a Continuous Compression Rate
When an advanced airway (such as an endotracheal tube or a supraglottic device) has been successfully placed, compressions do not need to be interrupted for breaths. The rescuer performing compressions continues at a rate of 100 to 120 per minute without pausing.
The rescuer managing the airway delivers breaths asynchronously, meaning the bag is squeezed without attempting to coordinate with the chest compressions. The recommended rate is one breath every 5 to 6 seconds, which equates to 10 to 12 breaths per minute. This lower, steady rate prevents hyperventilation, which can reduce the amount of blood returning to the heart.
The goal is to maximize the time spent compressing the chest while still providing adequate oxygenation. The simultaneous nature of the compressions and ventilations is possible because the advanced airway secures the passage of air directly into the trachea.
Delivering an Effective Bag-Mask Breath
The technique for squeezing the bag is standardized to ensure the breath is effective and safe. Each breath must be delivered slowly over approximately one second. Rapid or forceful compressions of the bag are discouraged because they increase the risk of air being pushed into the stomach rather than the lungs.
To prevent gastric inflation, the rescuer should only squeeze the bag enough to cause a visible, gentle rise of the patient’s chest. This visual confirmation is the primary indicator of sufficient volume.
Achieving a proper mask seal against the face is paramount for effective ventilation. A common technique involves a two-rescuer approach where one provider secures the mask tightly to the face using the EC-clamp method. The second rescuer then squeezes the bag.