Development of a new catheter-tip pressure transducer.

Two major disadvantages of the conventional catheter-tip transducer have been incapability to calibrate baseline pressure and to adjust sensitivity after insertion. A vast majority of conventional catheter-tip transducers are classified as gauge type. Due to their structure they are inherently incapable of recalibrating after insertion. We have overcome this problem by developing a new differential type catheter-tip transducer equipped with a lumen that connects a small chamber at the backside of the transducer to another external port. This lumen is capable of pressure passage. The output of this type depends on the difference between the two imposed pressures. This passage makes a baseline standard possible, when the end of the lumen is exposed to atmospheric pressure. When pneumatic pressure is imposed to the end of the lumen using a syringe, for example, the transducer output shifts up and down in accordance to that pressure, enabling baseline pressure recalibration and verifying the degree of sensitivity after insertion. By obtaining the following data, we confirmed the stability and availability of this transducer: Baseline drift less than 0.04 mmHg/8 hour, frequency characteristics flat up to 60 Hz, and common mode rejection ratio more than 46 dB.