An exemplary method includes acquiring impedance values over one or more respiratory cycles, determining an impedance span based on the impedance values and, based at least in part on the impedance span, determining cardiac condition or respiratory condition. Another exemplary method includes acquiring IEGMs over one or more respiratory cycles, determining evoked response measure values based on the IEGMs, determining an evoked response span based on the evoked response measure values and, based at least in part on the evoked response span, determining cardiac condition or respiratory condition. Other exemplary methods, devices, systems, etc., are also disclosed.