Face-mask ventilation is considered a fundamental procedural skill in emergency medicine. We have historically deployed it when patients are apneic, are hypoventilating, or need assistance with oxygenation. We keep bag-mask units at the head of every bed in the emergency department.
Explore This IssueACEP Now: Vol 36 – No 01 – January 2017
The world of airway management has evolved since the self-inflating bag-valve mask (BVM) was first created more than 50 years ago. In elective anesthesia, the laryngeal mask airway (LMA) has entirely replaced face-mask ventilation as a strategy for airway and anesthetic management in cases with a low risk of aspiration. In fact, the laryngeal mask is now used in the majority of elective anesthesia cases worldwide. It also has a rapidly growing presence in the world of prehospital care, especially in the United Kingdom and Europe.
The tip of the laryngeal mask wedges into the upper esophagus, behind the cricoid cartilage. It provides a wedge-shaped “stopper” to the upper esophagus; it’s not quite as effective as a tracheal tube in isolating the trachea from the esophagus but is far better than pushing gas by face mask into the shared upper aero-digestive tract of the pharynx.
LMA-type devices have replaced intubation and mask ventilation in elective anesthesia because they are better for both patients and operators. The laryngeal mask “sits” itself around the curve of the tongue and stays in position. The face mask requires continued downward pressure on the mask to maintain a seal. It can also be augmented by compressive head straps. The laryngeal mask can be easily used to bag a patient with one hand stabilizing the top of the device and the other squeezing the bag. This is not the case with a face mask. Holding the mask against the face works poorly, even with an “E-C grip” (using first and seconds digits [“C”] to hold the nasal bridge of the mask and the third, fourth, and fifth digits [“E”] to hold the lower mask).
Face-mask ventilation is as ergonomically smooth as walking in ski boots. The mask seals by being pushed onto the face, but this motion also pushes the mandible, base of the tongue, and epiglottis downward. And particularly in supine patients with no muscular tone, the base of the tongue, epiglottis, and mandible fall backward, causing “collapse” of the airway. Without continuous active lifting of the angle of the mandible, the airway obstructs. Conversely, the laryngeal mask seal is achieved by the same soft tissues falling backward onto the bowl of the device. It is not the inflation of a cuff that creates a mucosal seal; the newest and best laryngeal masks have, in fact, no cuffs at all. They mirror the laryngeal anatomy.