The<unk> , also known as an air-entrainment<unk> , is a medical device to deliver a known oxygen concentration to patients on controlled oxygen therapy. The<unk>  was invented by Moran Campbell at McMaster University Medical School as a replacement for intermittent oxygen treatment. Dr. Campbell was fond of quoting John Scott Haldane description's of intermittent oxygen treatment; "bringing a drowning man to the surface – occasionally". By contrast the<unk>  offered a constant supply of oxygen at a much more precise range of concentrations.
Venturi mask
Gas mask
N95 respirator
Oxygen mask
Pocket mask
Nasal cannula
Oxygen tent
Elastomeric respirator