The Bag-Valve-Mask (BVM) is a handheld medical device used to provide positive pressure ventilation to a patient who is not breathing or is breathing inadequately. Often known as an Ambu bag, this resuscitator is required in emergency kits for trained professionals. The device consists of a flexible bag connected to a face mask via a valve, allowing a rescuer to manually force air into the patient’s lungs. Effective use of the BVM is fundamental for oxygenation and survival in cases of respiratory failure or cardiac arrest.
The Optimal Two-Person Approach
The gold standard for BVM ventilation involves two operators. This technique significantly increases the likelihood of achieving an effective seal and delivering adequate air volume. The two-person method allows for a clear division of labor: one person focuses entirely on maintaining the airway and mask seal while the second concentrates on squeezing the bag. This two-rescuer approach delivers higher tidal volumes and provides a more effective seal compared to a solo attempt.
The operator positioned at the patient’s head uses both hands to secure the mask and maintain an open airway, employing the two-hand C-E grip. The thumbs and index fingers form two “C” shapes over the mask, pressing it firmly against the face. The remaining fingers form two “E” shapes, lifting the patient’s jaw (mandible) up toward the mask. This action maintains an open airway and prevents the tongue from obstructing the throat, creating a superior, air-tight seal.
The second operator stands to the side and focuses on compressing the bag at the correct rate and volume. For adults, this means delivering one breath every five to six seconds (10 to 12 breaths per minute). The bag should be squeezed slowly, over approximately one second, only until a visible rise of the chest is observed. This measured delivery prevents over-ventilation, which can push air into the stomach and increase the risk of regurgitation and aspiration.
Techniques for Solo Operation
In emergency situations, a single person may be required to operate the BVM, necessitating a compromise in technique. The single operator must manage both the critical mask seal and the bag squeeze simultaneously with only two hands. This often results in a less effective seal, as one hand must perform the work typically done by two hands in the optimal method.
The most common technique for solo use is the one-handed C-E grip, a modified version of the two-person method. The thumb and index finger of one hand form a “C” shape over the mask. The remaining three fingers form an “E” shape under the mandible to lift the jaw and secure the mask. The rescuer uses their other hand to squeeze the bag, delivering the ventilation.
This solo technique is inherently difficult because the single hand must apply enough pressure to maintain a seal while also lifting the jaw to open the airway. This simultaneous action is physically demanding and often leads to air leakage. The single-person technique is considered inferior due to the diminished seal quality, which reduces the amount of air successfully delivered to the lungs.
Confirming Successful Ventilation
The effectiveness of BVM ventilation must be confirmed to ensure the patient is receiving adequate oxygenation. The most direct sign of successful ventilation is observing a visible, gentle rise and fall of the patient’s chest with each squeeze of the bag. The volume delivered should be just enough to cause this chest movement, requiring only a partial squeeze of the bag. This helps prevent gastric inflation.
Maintaining a clear path for air delivery is necessary for success, often involving basic airway adjuncts. Devices such as an oropharyngeal airway (OPA) or nasopharyngeal airway (NPA) are inserted to hold the tongue and soft tissues away from the back of the throat. These adjuncts help ensure the airway remains open, allowing the delivered air to reach the lungs.
The rate of delivery must also be monitored closely, as ventilating too quickly or too often can be detrimental. For an adult with a pulse but who is not breathing, the target rate is one breath every five to six seconds. Advanced monitoring tools like capnography measure carbon dioxide in the patient’s exhaled breath, providing real-time objective data on the adequacy of ventilation.