Abstract: An inflatable plethysmographic cuff bladder comprising interior members for preventing the trapping of an inflating medium in the bladder when the inflating medium is rapidly evacuated therefrom. The interior members comprise members which project inwardly from facing interior walls of the bladder and members which are inserted in the bladder and extend outwardly toward the facing interior walls of the bladder. In all cases, the members cooperate to form channels assisting the flow of inflating medium from the bladder when the bladder is rapidly evacuated of the inflating medium.

Abstract: A strain gauge plethysmograph is provided comprising an elastic tubular member (2) filled with a non-mercury electrically conductive gallium-indium alloy which is fluid at room temperature. The tubular member (2) is attached to an inelastic strap member (1) at spaced points (5,6). The length of the strap (1) between the points of attachment (5,6) is limited to approximately 120% of the nominal length of the tubular member (2) for restricting stretching of the tubular member (2).