A bag valve mask (BVM) is sometimes known by it’s proprietary name Ambu bag (Artificial manual breathing unit) or generically as a manual resuscitator or ‘self-inflating bag’. It 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 as well as in hospitals as part of standard equipment found in emergency rooms or other critical care settings. Ref 1.
Yes, a bag mask device can be used in an ICU setting. Indeed, bag mask devices are the most common method that healthcare providers use to give positive-pressure ventilation during CPR. However, the bag mask ventilation technique is not recommended for a lone rescuer during CPR (the AHA guidelines recommend the use of a face mask to deliver breaths in a lone rescuer scenario). Furthermore, compressions-to-breaths ratios are not determined by the use of an AMBU bag or not but by the age/maturity of the patient and if the CPR is being administered by a lone rescuer or by multipe rescuers i.e. a compressions-to-breaths ratio of 30:2 is recommended for adults in both lone and multiple rescuer situations (i.e. 2 or more rescuers). Additionally, the lone rescuer utilizes the universal compressions-to-breaths ratio of 30:2 when administering CPR to victims of all ages except newly born infants. For children and infant CPR, a lone rescuer utilizes a 30:2 compressions-to-breaths ratio while 2 or more rescuers employ a compressions-to-breaths ratio of 15:2.
Rescuers administer ‘rescue breathing’ by providing breaths without compressions. Rescue breathing is indicated when an adult, child or infant has a pulse but is not breathing effectively. 10 -12 breaths are given per minute for adults and 12 -20 breaths per minute for children and infants.
Compressing the AMBU bag causes the gas inside the inflatable bag portion to be force-fed to the patient via a one-way valve. The gas is then delivered through the mask and into the patient’s trachea, bronchus and into the lungs. In order to be effective, a bag valve mask must deliver between 500 and 800 milliliters of air to a normal male adult patient’s lungs but if supplemental oxygen is provided, 400 ml may still be adequate. Compression using 2 hands will typically deliver more air than if one hand is used. However, the AHA guidelines recommend that excessive ventilation be avoided (only breaths sufficient to elicit a chest rise per breath are recommended). Ref 2.
Ref 2; American Heart Association. BLS for Healthcare Providers Student Manual. 2011. Part 2 to 4. Pgs 7 – 38.
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