Bag-valve-mask (BVM) ventilation is an essential emergency skill (see the video below). 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. [1, 2, 3] In the pediatric population, BVM may be the best option for prehospital airway support.  BVM ventilation is also appropriate for elective ventilation in the operating room when intubation is not required,  but it is now often substituted by the laryngeal mask airway. 
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. 
The masks come in many sizes, including newborn, infant, child, and adult (small, medium, and large). Choosing the appropriate size helps to create a good seal and, therefore, aids 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 greater than 90% oxygen to ventilated and spontaneously breathing patients. Bags lacking this feature deliver a high concentration of oxygen during positive pressure ventilation but only deliver 30% oxygen during spontaneous breaths. 
Indications for bag-valve-mask ventilation include respiratory failure (failure of ventilation and/or oxygenation) and failed intubation.
BVM ventilation is absolutely contraindicated in the presence of complete upper airway obstruction.
BVM ventilation is relatively contraindicated after paralysis and induction (because of the increased risk of aspiration).
Anesthesia is generally not required when indication exists. Elective ventilation in the operating room may require a sedative agent (eg, propofol).
Equipment required for bag-valve-mask (BVM) ventilation include the following:
Place towels under the patient’s head to position the ear level with the sternal notch. 
Extend the patient’s head slightly.
Open the airway
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, only perform a chin-lift maneuver.
Use an airway adjunct. Note the following:
Place an OPA in unresponsive patients without a gag reflex. 
Position the mask
Place the mask on the patient’s face before attaching the bag.  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.
Hold the mask in place
The one-hand E-C technique is shown below.
Use 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 below can also be used.
If a second person is available to provide ventilations by compressing the bag, a two-hand technique can be used.
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, as shown below.
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, as shown below.
No matter which technique is being used, avoid applying pressure on the soft tissues of the neck or on the eyes.
The two-hand technique is preferred to the one-hand technique and should be used whenever possible. 
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.
Ventilate the patient
Provide a volume of 6-7 mL/kg per breath (approximately 500 mL for an average adult). For a patient with a perfusing rhythm, ventilate at a rate of 10-12 breaths per minute. 
During cardiopulmonary resuscitation (CPR), give 2 breaths after each series of 30 chest compressions until an advanced airway is placed. Then ventilate at a rate of 8-10 breaths per minute. 
Give each breath over 1 second.  If the patient has intrinsic respiratory drive, assist the patient’s breaths. In a patient with tachypnea, assist every few breaths.  Ventilate with low pressure and low volume to decrease gastric distension.
Maintain cricoid pressure consistently. Note the following:
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. 
Care must be taken to avoid excessive pressure, which can result in compression of the trachea.
Assess the adequacy of ventilation. Note the following:
Observe for chest rise, improving color, and oxygen saturation.
Monitor for air leak.
Be cognizant of increasing gastric distention.
Pearls for bag-valve-mask (BVM) ventilation are as follows:
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 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 the 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 of water 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 and spontaneous ventilation, while bags lacking this feature only deliver about 30% oxygen during spontaneous breaths.