What is "bag valve mask"

n. (context medicine English) A bag, used to resuscitate a patient by supplying air or oxygen directly to the trachea and into the lungs

Use of manual resuscitators to ventilate a patient is frequently called "bagging" the patient and is regularly necessary in medical emergencies when the patient's breathing is insufficient ( respiratory failure) or has ceased completely ( respiratory arrest). Use of the manual resuscitator force-feeds air or oxygen into the lungs in order to inflate them under pressure, thus constituting a means to manually provide positive-pressure ventilation. It is used by professional rescuers in preference to mouth-to-mouth ventilation, either directly or through an adjunct such as a pocket mask. The full-form of AMBU is Artificial Manual Breathing Unit.