Development and in vitro validation of a device for measuring non-shunt cardiac output by nitrous oxide throughflow

Abstract

A system has been developed for measuring non-shunt cardiac output by the throughflow technique, using nitrous oxide in patients undergoing general anaesthesia. The throughflow measurement technique is a non-invasive method based on inert gas throughflow theory. In vitro validation of the measurement system was performed using a lung gas exchange simulator. The accuracy and precision of the throughflow measurement system was assessed by comparing measured and target values for five simulated values of non-shunt cardiac output, from 2.88 to 9.86l min-1. This showed an overall mean bias of -0.03l min-1 (range -0.00 to -0.10l min-1), with a mean coefficient of variation of the difference of 1.3..