Respiratory effort sensors

This is the channel that tells a central apnoea from an obstructive one: no effort means central. Two technologies coexist. The piezoelectric sensor on a belt is simple and robust and gives a qualitative waveform. Inductance plethysmography, the RIP bands, follows the real expansion of the ribcage and abdomen, and that is the method the AASM recommends when you want to quantify.