<P> A bag valve mask, abbreviated to BVM and sometimes known by the proprietary name Ambu bag or generically as a manual resuscitator or "self - inflating bag", is a hand - held device commonly used to provide positive pressure ventilation to patients who are not breathing or not breathing adequately . The device is a required part of resuscitation kits for trained professionals in out - of - hospital settings (such as ambulance crews) and is also frequently used in hospitals as part of standard equipment found on a crash cart, in emergency rooms or other critical care settings . Underscoring the frequency and prominence of BVM use in the United States, the American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiac Care recommend that "all healthcare providers should be familiar with the use of the bag - mask device ." Manual resuscitators are also used within the hospital for temporary ventilation of patients dependent on mechanical ventilators when the mechanical ventilator needs to be examined for possible malfunction, or when ventilator - dependent patients are transported within the hospital . Two principal types of manual resuscitators exist; one version is self - filling with air, although additional oxygen (O) can be added but is not necessary for the device to function . The other principal type of manual resuscitator (flow - inflation) is heavily used in non-emergency applications in the operating room to ventilate patients during anesthesia induction and recovery . </P> <P> 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 . </P>

When can a bvm (bag-valve-mask) be used