A bag mask device, often known as a BVM or manual resuscitator, is a portable tool used to provide positive pressure ventilation to individuals experiencing inadequate or absent breathing. This device is a self-inflating bag connected to a non-rebreathing valve and a face mask, designed to deliver air or supplemental oxygen manually. It offers immediate respiratory support in emergencies when a person cannot breathe effectively. The BVM is a standard component in resuscitation kits, used frequently in both out-of-hospital and hospital settings.
Basics of Bag Mask Ventilation
Effective use of a bag mask device begins with establishing a patent airway and achieving a proper mask seal. To open the airway, a rescuer typically employs the head-tilt/chin-lift maneuver, which involves tilting the head back and lifting the chin to move the tongue away from the back of the throat. If a spinal injury is suspected, a jaw-thrust maneuver is used instead to avoid neck movement. Once the airway is open, the mask must form a tight seal over the patient’s nose and mouth to prevent air leakage. A common technique for this is the C-E clamp, where the thumb and index finger form a “C” around the mask while the remaining fingers form an “E” along the jawline to lift it into the mask.
Delivering a breath with a bag mask device involves a slow, steady squeeze of the bag over approximately one second, just enough to cause the chest to visibly rise. Avoid excessive force or rapid inflation, which can lead to complications. Over-squeezing the bag or delivering too many breaths can force air into the stomach, known as gastric inflation. Gastric inflation can compromise ventilation by pushing on the diaphragm, and in severe cases, it may lead to vomiting and aspiration, where stomach contents enter the lungs. Therefore, deliver only the necessary volume to achieve chest rise.
Breathing Rates for Adults, Children, and Infants
The number of breaths to deliver with a bag mask device varies significantly with age, particularly when the patient has a pulse but is not breathing adequately. For adults, the recommended rate for rescue breathing is one breath every 5 to 6 seconds, which translates to 10 to 12 breaths per minute.
For children (from 1 year to puberty) and infants (under 1 year), the recommended rescue breathing rate is more frequent. They should receive one breath every 3 to 5 seconds, aiming for 12 to 20 breaths per minute. These specific rates help ensure adequate oxygenation without causing hyperventilation, which can have negative effects on circulation.
Adjusting Breaths for Emergency Scenarios
Breathing rates with a bag mask device change in specific emergency situations, particularly during cardiopulmonary resuscitation (CPR) or when an advanced airway is in place. During CPR without an advanced airway, the integration of breaths with chest compressions follows a specific ratio. For a single rescuer, the guideline is to deliver two breaths after every 30 chest compressions for adults, children, and infants. If two rescuers are present for children and infants, the ratio changes to two breaths after every 15 compressions.
In cases of suspected opioid overdose where the person is not breathing but still has a pulse, initial rescue breathing with the bag mask device is critical for oxygenation. The breathing rates generally follow the standard rescue breathing guidelines for the patient’s age group until naloxone can be administered and takes effect. This immediate oxygen delivery is a priority for managing opioid-induced respiratory depression.
When an advanced airway, such as an endotracheal tube, has been inserted, breaths are delivered continuously without pausing chest compressions if CPR is ongoing. For all ages with an advanced airway, the recommended rate is approximately one breath every 6 seconds, equating to 10 breaths per minute. For infants and children with an advanced airway, a slightly higher rate of 20 to 30 breaths per minute (one breath every 2-3 seconds) may be considered. This continuous ventilation helps maintain consistent oxygen delivery to the lungs.
Recognizing Effective Ventilation
Observing specific signs during bag mask ventilation confirms effective breath delivery. The most important indicator is visible chest rise and fall with each squeeze of the bag. This confirms air enters the lungs, not elsewhere. The absence of visible chest rise suggests an ineffective seal or an obstructed airway, requiring immediate adjustment of technique or patient position.
Another sign of effective ventilation is the absence of gastric distension, meaning the stomach should not swell. Gastric distension indicates that air is entering the stomach instead of the lungs, often due to excessive pressure or improper airway management. Listening for air escaping during exhalation also helps confirm successful ventilation. Additionally, an improvement in the patient’s color, such as a reduction in cyanosis (bluish discoloration), suggests improved oxygenation. Consistent monitoring of these visual and auditory cues is essential for ongoing effective ventilation.