Bag-Valve-Mask Ventilation

Bag-valve-mask (BVM) ventilation[1] is an essential emergency skill. This basic airway management technique allows for oxygenation and ventilation of patients until a more definitive airway can be established and in cases where endotracheal intubation or other definitive control of the airway is not possible. For the emergency medical technician, basic BVM ventilation is most often the only option for airway management.[2, 3, 4]

In the pediatric population, BVM may be the best option for prehospital airway support.[5, 6]  BVM ventilation is also appropriate for elective ventilation in the operating room (OR) when intubation is not required,[7]  but it is now often replaced in this setting by the laryngeal mask airway.[8]

BVM ventilation requires a good seal and a patent airway. Practice with this important skill increases the clinician’s ability to provide effective ventilation. Adjuncts such as oral and nasal airways can aid with ventilation by relieving physiologic obstruction and by opening up the hypopharynx. Certain factors predict difficult BVM ventilation. These include the presence of facial hair, lack of teeth, a body mass index (BMI) greater than 26, age older than 55 years, and a history of snoring.[9]

Masks come in many sizes, including newborn, infant, child, and adult (small, medium, and large). Choosing the appropriate size helps create a good seal and thereby facilitates effective ventilation.

Bags for BVM ventilation also come in different types. Newer bags are equipped with a pressure valve. Some bags have one-way expiratory valves to prevent the entry of room air; these allow for delivery of more than 90% oxygen to ventilated and spontaneously breathing patients. Bags lacking this feature deliver a high concentration of oxygen during positive-pressure ventilation (PPV) but deliver only 30% oxygen during spontaneous breaths.[8]

Indications for BVM ventilation include respiratory failure (failure of ventilation, oxygenation, or both) and failed intubation.

BVM ventilation is absolutely contraindicated in the presence of complete upper-airway obstruction. It is relatively contraindicated after paralysis and induction (because of the increased risk of aspiration).

Equipment required for bag-valve-mask (BVM) ventilation include the following:

• BVM with reservoir (see the image below)
• Oxygen connector tubing
• Oxygen source
• Suction
• Nasopharyngeal airway (NPA)
• Oropharyngeal airway (OPA)

Anesthesia

Anesthesia is generally not required when an indication exists. Elective ventilation in the operating room may require a sedative agent (eg, propofol).

Positioning

Place towels under the patient’s head to position the ear level with the sternal notch.[2] Extend the patient’s head slightly.

Bag-valve-mask (BVM) ventilation (see the video below) is an essential emergency skill.[10] This basic airway management technique allows oxygenation and ventilation of patients until a more definitive airway can be established and may be used in cases where endotracheal intubation or other definitive control of the airway is not possible.

In the setting of the COVID-19 pandemic, BVM ventilation should be performed with caution and avoided if possible; when indicated, it must be performed in accordance with recommendations from national and international organizations.[11]  Because BVM ventilation is an aerosol-generating procedure, the addition of high-efficiency particulate air (HEPA) filtration to filter expired air is warranted. All reusable patient-care equipment must be cleaned and disinfected before use on another patient, according to the manufacturer’s instructions.

Airway placement

Perform the head-tilt chin-lift maneuver or the jaw thrust. In patients with suspected cervical spine injury, do not perform a head-tilt; rather, perform only a chin-lift maneuver.

Use an airway adjunct. Note the following:

• Place an oropharyngeal airway (OPA) in unresponsive patients without a gag reflex ^[12]
• If the patient is awake, place one or two nasopharyngeal airway (NPA) devices instead, which may be better tolerated; however, because of the risk of intracranial placement, avoid the use of a NPA in patients with significant  head and  facial trauma ^[12]

Mask positioning

Place the mask on the patient’s face before attaching the bag.[8]  Cover the nose and the mouth with the mask without extending it over the chin. Change the size of the mask, as appropriate, to create a good seal.

Various methods of mask positioning have been described. The one-hand E-C technique is shown in the images below. Using the nondominant hand, create a C-shape with the thumb and index finger over the top of the mask, and apply gentle downward pressure. Hook the remaining fingers around the mandible, and lift it upward toward the mask, creating the E.

The alternative one-hand technique shown in the image below can also be employed.

If a second person is available to provide ventilations by compressing the bag, a two-hand technique can be used (see the image below). Create two opposing semicircles with the thumb and index finger of each hand to form a ring around the mask connector, and hold the mask on the patient’s face. Then lift up on the mandible with the remaining digits.

Alternatively, place both thumbs opposing the mask connector, using the thenar eminences to hold the mask on the patient’s face, while lifting up the mandible with the fingers (see the image below).

No matter which technique is used, it is essential to avoid applying pressure on the soft tissues of the neck or on the eyes.

Place the web space of the thumb and index finger against the mask connector. Push downward with gentle pressure. Wrap the remaining fingers around the mandible and lift it upward.

The two-hand technique is preferred to the one-hand technique and should be used whenever possible.[13, 14]  The National Association of EMS Physicians (NAEMSP) has recommended that a two-person approach be followed for prehospital BVM ventilation whenever feasible.[10]

Ventilation

Provide a volume of 6-7 mL/kg per breath (~500 mL for an average adult). For a patient with a perfusing rhythm, ventilate at a rate of 10-12 breaths/min.[12]

During cardiopulmonary resuscitation (CPR), give two breaths after each series of 30 chest compressions until an advanced airway is placed. Then ventilate at a rate of 8-10 breaths/min.[12, 15]

Give each breath over 1 second.[12]  If the patient has intrinsic respiratory drive, assist the patient’s breaths. In a patient with tachypnea, assist every few breaths.[16]  Ventilate with low pressure and low volume so as to minimize gastric distention.

Maintain cricoid pressure consistently, keeping the following considerations in mind:

• This pressure is meant to compress the esophagus and reduce the risk of aspiration; however, it does not completely protect against regurgitation, especially in cases of prolonged ventilation or poor technique ^[2]
• Care must be taken to avoid excessive pressure, which can result in compression of the trachea

Assess the adequacy of ventilation, taking care to do the following:

• Observe for chest rise, improving color, and oxygen saturation
• Monitor for air leakage
• Be cognizant of increasing gastric distention

Although the evidence is not conclusive, some have found capnography to be a feasible and potentially useful means of assessing BVM ventilation in the context of CPR, particularly in neonates.[17]

Pearls

The following tips and comments may facilitate the performance of BVM ventilation:

• Lift the mandible up to the mask rather than pushing the mask down onto the face
• An adequate seal can more easily be made with a mask that is too big than with one that is too small
• Leave dentures in place, when possible, to improve mask seal
• If the patient's facial hair makes a seal difficult to obtain, apply a water-soluble lubricant over the beard to improve the contact between the face and the mask
• If one-handed mask ventilation is not effective, switch to the two-handed technique
• Insert NPA devices bilaterally if necessary
• The best way to prevent aspiration is with good technique, including low-pressure, low-volume ventilation with slow insufflation; newer bags have built-in pressure valves; the green zone includes pressures up to 20 cm H ₂O and corresponds to the lowest risk of gastric distention
• Note the type of bag being used; bags with one-way expiratory valves allow greater than 90% oxygen delivery during both positive-pressure ventilation (PPV) and spontaneous ventilation, whereas bags lacking this feature deliver only about 30% oxygen during spontaneous breaths

Potential complications of BVM ventilation include the following:

• Aspiration
• Hypoventilation
• Hyperventilation