A Computer Monitored, Recirculating, Equilibrium Test Circuit for Artificial Blood Oxygenator Gas and Heat Transfer Characterization

Abstract

An In Vitro test circuit that features continuous direct monitoring of blood gases, pH, temperature, hemoglobin O2 saturation, blood flow, gas flow and pressure is presented. Previous test circuit designs and features are presented. A microcomputer monitors the directly measured parameters, presents the investigator with test control variables and allows the user to collect gas and heat transfer data with a single key stroke. Control parameters and test results are presented immediately and stored in a data file for statistical analysis and graphic presentation. The microcomputer is employed to present the technologist with AAMI Standard test condition parameters and variables that quantitate oxygenator "stress" to allow rapid control of the deoxygenator loop. The computer assisted ability to control test conditions facilitates testing, improves the statistical consistency of the data and minimizes time to collect, analyze and compare device data. Employing the computer test circuit decreased study time for a single device characterization from 8 hours to 2-3 hours. Additionally, hemoglobin P50, mixed venous blood conditions, the forcing function for O2 and CO2 transfer, the test oxygenator respiratory quotient and failure conditions are easily monitored, eliminating the recording of invalid data.