Airway Skills 2:
Bag-Valve-Mask Use
Using a bag-valve-mask (BVM) is an important skill. Following are guidelines for doing it well:
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Use an oral or nasal airway to deliver oxygen beyond the patient's tongue.
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Obtain a good mask-face seal by forming a C with your thumb and forefinger. Use your other fingers to grasp the jaw, holding the mask firmly against the face.
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In some patients, obtaining a seal may be difficult. An assistant may use two hands to obtain the seal.
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Be cognizant of the tidal volume being delivered. For both adults and (PEDS) children, tidal volume should be about 10 to 15 cc/kg. A 12 kg 1-year-old child should receive a tidal volume of 120 to 180 cc, while a 70 kg adult should receive a tidal volume of 700 to 1050 cc. Watch for rise and fall of the chest as an indication that the patient is being well ventilated.
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If possible, use a BVM with an attached pressure monitor. These disposable devices are inexpensive and may be adapted to most BVMs. Knowing how much pressure is being generated helps the BVM user deliver the correct tidal volume. These monitors measure tracheal pressure in cm of H2O. A pressure of 20 to 30 cm H2O is usually the goal. Too much pressure results in gastric distension.
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PEDS: Ventilatory rate varies from 20 ventilations per minute in small children to 12 to 15 ventilations per minute in adults. In severe asthma, a rate of only 7 to 8 ventilations per minute may be indicated.
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Cricoid pressure (Sellick's maneuver) should be optional and may not prevent gastric insufflation and regurgitation.
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It is very useful to sense the degree of resistance felt when the lungs are ventilated. Decreased lung compliance is an important component of asthma and lung contusion. Under these circumstances, it may be necessary to use unusually large amounts of pressure.
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A form of PEEP may be administered with a BVM by maintaining compression of the bag for about a second at the end of the inspiratory cycle. This is sometimes referred to as "recruitment" because it allows delayed opening of alveoli, recruiting more effective ventilation in the face of atelectasis. Oxygen saturation can sometimes be improved with this maneuver.
Reference
McGee JP, Vender JS. Nonintubation management of the airway: mask ventilation in Airway management: principles and practice. Benumof JL, Ed. St. Louis, 1996, Mosby; 228-254.