b'ChapterResuscitation SystemsA minimum of 2 trained rescuers are required to provide ventilation for a nonbreathing patient (one to manage the airway, mask and seal and the second to operate the soft bag). There are two main groups:Oxygen powered - manual or demand valve resuscitation systems.Hand poweredsoft bag and mask resuscitation systems.Non-rebreathing circuits include a non-return valve which exhausts the expired gas (carbon dioxide, nitrogen) into the atmosphere. A high oxygen flow rate of 8 to 15 litres per minute is required.Partial rebreathing circuits (semi closed systems) are valve systems that enable a portionof the expired gas to be re-breathed and a portion to be exhausted into the atmosphere. The gradual build up of carbon dioxide is thereby prevented by a flushing effect by using oxygen flow rates of 7 to 10 litres per minute.Rebreathing circuits (closed systems).An example is a crystal soda lime absorption system that filters carbon dioxide from the expired gas.The purified gas is then returned to the patient and supplemented with additional 100% oxygen that is equivalent to that which is metabolised within the body.Oxygen flow rates are quite low (0.5 to 2.5 litres per minute) and only carbon dioxide is removed, therefore the rebreathing circuit is not used for overcoming poisonous gas inhalation.Mechanical ResuscitatorsOxygen powered resuscitatorsA demand valve oxygen powered resuscitator system is where a non breathing circuit with a demand valve assembly is connected to an oxygen supply.A breathing patient will trigger the demand valve and oxygen will automatically flow until inhalation is finished. Expired gases will then pass into the atmosphere.In a non breathing patient, a manual override system is used to inflate the lungs.This is activated by manually pressing a button valve lever. Any excess pressure into the lung will be prevented by a pressure relief valve.Hand powered resuscitatorsA.Dependant on oxygen supplyFirst aiders prefer the soft bag mask system because the movement and feel of the bag helpindicate the presence or absence of breathing and also the general condition of the airway.There are two main systems:Soft bag and mask partial rebreathing system.This is where high oxygen flow rates in a partialre breathing circuit flush out expired carbon dioxide.Soft bag and mask closed circuit system.This works on rebreathing low flow rates of oxygen ina closed circuit with soda lime crystals that absorb expired gases by combining with a chemical.B.Non dependant on oxygen supplyIn the event of respiratory arrestpocket maskSelf inflating soft bag and mask resuscitation systems. The self inflating bag and mask system isidentical to the other systems but there is no oxygen supply cylinder.244 Advanced Resuscitation'