What is the advantage of thermistors versus pressure sensors for flow sensing?
Although the trend is moving toward pressure sensing, the vast majority of labs and systems still rely on thermistors and will probably continue to do so. In general, pressure cannula is more sensitive than thermistors, specifically regarding mild hypopnea events, which demonstrate changes in the shape of the trace, rather than a decrease in its amplitude. Pressure sensing records, however, a large number of false events, again due to the very complex waveforms it generates, which are very easy to misinterpret. There is also a major problem of mouth breathing, confusing the pressure sensor located on the nose. To compensate for the thermistors’ lower sensitivity to hypopnea, we’ve designed a relatively high flow threshold in the SleepStrip algorithm, resulting in good overall sensitivity at a slightly lowered specificity (more false positives), an acceptable specification for a screening tool. Comparing SleepStrip readings to pressure cannula readings will indeed show a lower RDI, but
