Ambu Bag
Synonyms
Bag valve mask
BVM
Ambu bag
Definition
A hand-held device used to provide positive pressure ventilation to a patient who is not breathing or who is breathing inadequately. The device is a normal part of a resuscitation kit
Indications for use
When a patient's breathing is insufficient (respiratory failure)
When a patient has ceased completely (respiratory arrest).
The BVM resuscitator is used in order to manually provide mechanical ventilation in preference to mouth-to-mouth resuscitation (either direct or through an adjunct such as a pocket mask).
Components
The BVM consists of
a flexible air chamber
a face mask via
a shutter valve.
Way of functioning
When the bag is squeezed, the device forces air through into the patient's lungs;
when the bag is released, it self-inflates
Drawing in air or oxygen ( O2 supplied from a regulated cylinder)
The patient's lungs deflate to the air through the one way valve.
Can also be attached to an alternate airway adjunct, such as an endo-tracheal tube or laryngeal mask airway, instead of the mask with which it is supplied.
Often a small HME filter is also used (Heat & Moisture exchanger - a Humidifying / bacterial filter )
A bag valve mask can be used without being attached to an oxygen tank to provide air to the patient, but supplemental oxygen is recommended since it increases the partial pressure of oxygen in the air, helping to increase perfusion in the patient.
Most devices also have a reservoir which can fill with oxygen while the patient is exhaling (a process which happens passively), in order to increase the amount of oxygen that can be delivered to the patient to nearly 100%.
Bag valve masks come in different sizes to fit infants, children, and adults.
Ambu bag can be cleaned and reused
Disposable ones are available
Method of operation
The bag delivers 500 to 600 ml at every squeeze
12 respirations per minute in an adult and 20 per minute in a child or infant.
The mask portion of the bag must be properly sealed around the patient's face ;
Otherwise, air escapes from the mask and is not pushed into the lungs.
While the bag is being used the patient may need cardiac massage too; for every four cardiac compressions one bag squeeze will do.
Care is taken to avoid damage to the lungs by over inflation.
An endotracheal tube can be inserted which can substitute for the mask portion of the BVM. This provides a more secure fit and is easier to manage during emergency transport, since the ET tube is sealed with an inflatable cuff in the trachea, so that any regurgitation cannot enter the lungs.
The concept for the original Ambu bag was developed in 1953 by the German engineer, Dr. Holger Hesse, and his partner, Danish anaesthetist, Henning Ruben.
