The LSP Demand/Resuscitator Valve is designed to provide 100% oxygen to breathing or non-breathing patients in an emergency situation. The valve can be used in conjunction with a portable oxygen cylinder equipped with a pressure regulator or with a central oxygen source. The valve operates on a regulated oxygen supply of 40-60 psig and reduces this pressure to a physiologically acceptable Level with a pressure limit of 60±5 cm H2O. The slight negative pressure created by a spontaneously breathing patient's inspiratory effort triggers the valve from a non-flow state to a flowing state. The non-breathing valve permits it to be used as a resuscitator in combination with a manually operated button located on top of the valve. The valve can be utilized with a mask, endotracheal tube or tracheotomy tube.