In what situation is bag-valve-mask (BVM) ventilation most effective?

Bag-valve-mask (BVM) ventilation is most effective in apneic patients without airway obstruction because these patients are unable to breathe on their own, yet the airway is clear, allowing for successful delivery of air to the lungs. In this scenario, placing a well-fitting mask over the patient’s face and providing positive pressure ventilation effectively fills the lungs with oxygen-rich air, which is crucial for maintaining oxygenation in the absence of spontaneous respiration.

When using a BVM, it's essential that the airway is unobstructed to ensure that the delivered breaths can flow freely into the lungs. Additionally, establishing a good seal with the mask and employing the appropriate technique to squeeze the bag helps maximize the efficiency of ventilation. In cases where the airway is obstructed, such as with a foreign body or severe edema, or when the patient still has some respiratory drive, the effectiveness of BVM is significantly hindered. This highlights why the best application for BVM is in those who are apneic but have a patent airway.