Fig. 2
From: Non-acid reflux and sleep apnea: the importance of drug induced sleep endoscopy
Multichannel impedanciometry (Z1-Z6) 24 h recording with multiple episodes of GER due to non acid reflux (gas). Ph1 showed peaks of non acid reflux (Ph > 4). Channels Z1 to Z6 showed the chapters where there is an increase of the impedance due to gas