Mouthpiece with a tongue retractor

Abstract From the Canadian patent

A mouthpiece comprising a tubular member about which a person may voluntarily place his lips in an air-tight manner for preventing a passage of air between the lips and the mouthpiece, said tubular member having a principal and a side air passageway and a blade-like member extending from one edge thereof, forming a tongue retractor for restricting the movement of the person's tongue and preventing it from obstructing a flow of air through the principal air passageway is described. For evaluating respiratory processes the cross-sectional area, of the principal air passageway of the tubular member is large enough so as not to significantly affect the then current physiology of the respiratory …