Supplemental oxygen therapy is used to aid patients in need of respiratory help. Traditionally, patients with depressed 

breathing are prescribed 1) compressed oxygen or 2) oxygen concentration systems. Most commonly, compressed oxygen is delivered through medical air supply from a wall outlet or portable oxygen tanks. In a hospital setting where depressed breathing monitoring is critical, the oxygen source is from the wall. A schematic of a typical oxygen delivery system is shown below. Oxygen is delivered through the wall into a pressure reducing valve. The pressure of the inlet air is shown through the pressure gauge. A safety valve is placed in the path of the air to prevent high pressure air. Safe pressures of air then flow through the flow meter where they can be further adjusted. The flow meter has a ball indicator that moves with respect to a manual flow regulating valve on the flow meter. The air travels through a humidifying cup and then out into an outlet. Finally, oxygen is delivered through eight types of cannulas, 1) nasal cannula, 2) simple mask, 3) nonrebreather mask, 4) Venturi mask, 5) face tent, 6) manual resuscitation bag, 7) tracheostomy mask and 8) oxygen hood.