Physiological pressure measuring system

Abstract

A physiological pressure measuring system usable in conjunction with an intravascular infusion line leading to a patient whose pressure is to be monitored. The system includes a detector having a transparent chamber interposed in the line and a flexible bulb mounted therein whose exterior is subjected to the fluid pressure in the chamber, the bulb interior communicating with a flexible pipe terminating in a hollow plug vented to the atmosphere whereby the bulb is caused to collapse when the infusion fluid pressure which reflects the physiologial pressure is greater than atmospheric. Associated with the detector is a fluid pressure transducer yielding a signal as a function of the applied pressure, the transducer input port being in the form of a tubular jack adapted to telescopically receive the plug. When the plug is inserted in the jack, a seal is effected to create a closed air column which exerts pressure on the transducer. The effective length of the column depends on the relative axial position of the plug; and as the plug is advanced into the jack, the column is shortened to thereby compress the air entrapped therein. A point is reached in the course of advance when the column pressure matches the chamber fluid pressure, limited further advance resulting only in dilation of the bulb without any change in column pressure. The transducer senses the matching column pressure to provide the desired physiological pressure reading.