Also known as a bag valve mask or BVM. It is a hand-held device which is used to provide ventilation to a patient who is not breathing or who is breathing inadequately. After it is squeezed, the bag is self-inflating. A BVM is a normal part of a resuscitation kit for trained professionals. It is commonly used by ambulance crews and hospitals, and is an essential part of a crash cart. It is also extensively used in extensively in the operating room to ventilate an anesthetized patient in the period of time before a mechanical ventilator is attached.