Abstract: A syringe for collecting a blood sample includes a cylindrical housing having a hollow needle at one end. A plunger slidably mounted within the housing defines a chamber within which blood collected by the needle is received. A hydrophilic bypass element disposed between the rim of the plunger and the inside surface of the housing forms a passageway through which air is exhausted as blood enters the chamber under arterial pressure. The passageway is automatically closed to prevent leakage from the chamber when the chamber becomes filled with blood and the bypass element is wetted. An alternate embodiment wherein the hydrophilic bypass element is in the form of an annular sleeve extending around the rim of the plunger is shown.

Abstract: A system for monitoring respiratory pressure or other pressure-variable function at a remote location develops within a transmitter terminal a carrier tone frequency-modulated according to applied pressure. The carrier tone is conveyed over a conventional telephone channel to a receiver terminal wherein an analog signal is developed from the carrier tone for application to recording or indicating instruments. The base frequency and deviation characteristic of the carrier tone is preset and non-user adjustable to avoid the necessity of setting up the system prior to use. To assure system continuity a pilot tone is generated at the receiver terminal and conveyed over the telephone channel to the transmitter terminal, and an alarm is sounded at the terminals when either but not both of the pilot and carrier tones are absent in the telephone channel. The terminals are preferably constructed within compact housings having wells for receiving the handsets of associated telephones for convenience of use.