Original Article

A Technique for Computerized Monitoring and Analysis of a Pulsed Doppler System to Count ECC Gaseous Microemboli

Extracorporeal Technologies, Inc., Indianapolis, IN

^* Direct communications to: J.B. Riley, 9210 Golden Oaks West, Indianapolis, IN 46260

Abstract

A computer with analog to digital conversion capabilities is employed to monitor the peak signal from a pulsed doppler system designed to non-invasively count microbubbles. The bubble detector has two probes for measuring ECC component inlet and outlet gaseous microemboli (GME) counts. The detector selectively processes signals from reflected targets with the impedance of gas.

An indirect calibration procedure employing screen filters is outlined. The peak signal output of the bubble detector is linear in response to GME expected diameter and the GME detector measurement system is subject to coincidence error.

The multiple GME size frequency distribution samples measured at ECC test device inlet and outlet are passed to a statistical software package. The measured GME size frequency distributions fit a normal curve. The increase in the number of smaller GME at the outlet of certain ECC components suggests a coincidence error in the bubble detector or that the ECC device is breaking larger bubbles into smaller bubbles.

Consistent, small standard deviation, and useful GME profiles may be rapidly collected for statistical analysis and comparison by a microcomputer. This data collection system is capable of quantitating ECC component GME production or removal, debubbling process times, necessity for CO₂ gas flush and routine clinical maneuvers.