A supplemental air diffusion device is shaped and configured to be attached to the body or clothing of a patient below the head and deliver supplemental air toward the mouth and nose of the patient. The supplemental air diffusion device includes a frustroconicoidal air diffusion body that has a smaller inlet opening at an inlet end and an enlarged diffusion opening at a diffusion end. An air inlet stem is integrally attached to the air diffusion body and includes a plurality of ribs and/or recesses for releasably locking a female connector of an air supply hose over the inlet stem. A pair of spaced-apart slits are provided through a flange extending laterally from an outer surface of the air diffusion device. Initially separate accessory patient attachment clamps are looped through the slits and provide for releasable attachment of the air diffusion device to a patient's clothing. A kit may include an air diffusion device, one or more accessory patient attachment clamps, and an air supply hose for establishing fluid communication between the air diffusion device and an air supply.