Venturi mask

[1][2] The mask 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's description of intermittent oxygen treatment; "bringing a drowning man to the surface – occasionally".

[3][4] By contrast the venturi mask offered a constant supply of oxygen at a much more precise range of concentrations.

Other brands of mask have a rotating attachment that controls the air entrainment window, affecting the concentration of oxygen.

Administration of too much oxygen may lead to a reduction in their respiratory rate and retention of carbon dioxide, and ultimately to reduced consciousness or even death.