ABSTRACT

A self-inflating bag with a non-rebreathing valve and mask is found on a cardiac arrest trolley. This is a compact and portable ventilating system that does not require a pressurised gas supply to work. The main component in a self-inflating resuscitation bag is the non-rebreathing valve. Their function is to ensure that gas flows out of the self-inflating bag and into the patient during inspiration and that exhaled gases pass out through the expiratory port and do not re-enter the self-inflating bag. During positive pressure ventilation, as the bag is squeezed, the bobbin is pushed across and closes the expiratory port, allowing fresh gas to enter the patient. During expiration, as the bag relaxes, the bobbin shifts to the opposite side and closes the inspiratory port, allowing exhaled gases to escape through the expiratory port.