BAG AND MASK VENTILATION
Bag and mask ventilation (BMV) is the first step in airway management in most situations, with the exception of patients undergoing rapid sequence intubation. Rapid sequence inductions avoid BMV to avoid stomach inflation and to reduce the poten-tial for the aspiration of gastric contents in nonfasted patients and those with delayed gastric emptying. In emergency situations, BMV precedes attempts at intubation in an effort to oxygenate the patient, with the understanding that there is an implicit risk of aspiration.
As noted above, the anesthetist’s left hand sup-ports the mask on the patient’s face. The face is lifted into the mask with the third, fourth, and fifth fingers of the anesthesia provider’s left hand. The fingers are placed on the mandible, and the jaw is thrust for-ward, lifting the base of the tongue away from the posterior pharynx opening the airway. The thumb and index finger sit on top of the mask. If the air-way is patent, squeezing the bag will result in the rise of the chest. If ventilation is ineffective (no sign of chest rising, no end-tidal CO 2 detected, no mist in the clear mask), oral or nasal airways can be placed to relieve airway obstruction secondary to redun-dant pharyngeal tissues. Difficult mask ventilation is often found in patients with morbid obesity, beards, and craniofacial deformities.
In years past, anesthetics were routinely delivered solely by mask administration. In recent decades, a variety of supraglottic devices has permitted both airway rescue (when BMV is not possible) and routine anesthetic airway man-agement (when intubation is not thought to be necessary).