An ambu bag is used by nurses or respiratory therapists. It forces air inside the lungs similar to mouth to mouth resuscitation. Ambu bags are available in different sizes for adults, children and infants. Every patient requires different tidal volume of air depending upon his or her age. An ambu bag consists of one way valve, bag and adapter. The bag could be attached directly to an endotracheal tube or to a mask with the help of the adapter provided. The one way valve in the device allows the flow of oxygen to the patient and also prevents backward flow of exhaled air. Te latest version of ambu bags come with a reservoir which helps in enhancing the oxygen flow rate entering the patient.