Physiological pressure measuring system

Claim 1

A physiological pressure measuring system comprising: (A) an intravascular infusion set having a line carrying fluid to a patient whose pressure is to be monitored: (B) a detector having a transparent chamber interposed in the line whereby the fluid carried to the patient flows through the chamber, and a flexible bulb mounted in the chamber, the exterior of the bulb being subjected to the pressure of the fluid in the chamber, the interior of the bulb communicating with a flexible pipe terminating in a hollow detector plug initially vented to the atmosphere whereby the bulb is collapsed when the chamber fluid pressure is greater than atmospheric; (C) a transducer producing an analog signal as a function of applied pressure; and (D) an input port coupled to said transducer to apply pressure thereto, said input port being defined by a tubular transducer jack adapted to telescopically receive and seal from the atmosphere said hollow detector plug which is axially advanceable into said transducer jack such that when a pressure reading is to be taken, an operator then inserts and axially advances the detector plug into said transducer jack to create in said pipe an air column whose effective length is determined by the length of the pipe and the variable length of the telescoping plug and jack and which is closed by the collapsed bulb to entrap the air therein, the effective length of the air column therefore depending on the axial position of the detector plug so that as the detector plug is advanced by the operator into the transducer jack to shorten the column, the entrapped air then is compressed to exert a pressure on the transducer, the parameters of the pipe and the telescoping plug and jack relative to the full range of pressures encountered in patients being such that a point is reached in the course of said advance where the air pressure in the column matches the pressure of fluid in the chamber, beyond which point further advance of the detector plug results in partial dilation of the collapsed bulb to relieve any increase in the column air pressure whereby the matching column pressure sensed by the transducer is maintained to provide the desired pressure reading.