Figure 4. Flow, Drive, and Dilator Muscles in Drive-Dependent v. Classic OSA.
A) Note that drive falls in tight concordance with falling flow during events in drive-dependent OSA (right) in contrast to classic OSA where flow fails to rise when drive increases (left). B) Drive falling provides a reduced stimulus for genioglossus activity (also falls then rises during events). Note the temporal association between drive and genioglossus activity particularly in drive-dependent OSA (right). C) Multi-patient “endogram” shows flow-drive profiles for both groups. Drive-dependent patients exhibited greater loss of flow and increase in event risk (color bar) with falling drive v. classic patients. Endotypic differences can also be seen: drive-dependent patients had a greater muscle effectiveness (flow-drive slope), lower arousal threshold (green vertical line), but similar collapsibility (flow at drive=100%, “Vpassive”) compared with classic OSA. D) However, average genioglossus-drive profiles were similar between groups. EMG data presented as %eupnea (i.e. data normalized by peak EMG at drive=100%).