An electronic simulator for testing infant apnoea monitors that uses actual physiologic data

An electronic simulator of physiologic signals used in infant monitoring ha s been designed, constructed and applied in the Collaborative Home Infant M onitor Evaluation (CHIME). A unique feature of the simulator is that it con tains actual physiologic waveforms recorded From infants rather than artifi cial, idealized signals. The simulator stores breathing waveforms that can be used to test transthoracic-impedance- and inductance-plethysmography-bas ed monitors, and heart rate channels are tested by playing a neonatal QRS c omplex at preset fixed rates or a variable rate as determined from infant r ecordings. The transfer characteristics of the simulator ate constant over frequencies ranging from 0.5 to 8 Hz for the respiration channels. Data sto red in memory are divided into 60 second epochs that can be presented to th e monitor, being tested in a programmable sequence. A group of 66 CHIME mon itors was tested using a simulator programmed with 17 apnoea and bradycardi a waveforms. The agreement between monitors as to the duration of detected apnoea decreases as the amount of artefact in the signal increases. Discrep ancies between monitors in detecting apnoea duration were found to be simil ar to inconsistencies between CHIME investigators manually scoring similar waveforms.