Methods for treating a patient and further to devices for performing such treatment, e.g., methods and devices to perturb at least one physiological system and deliver therapy to the patient based on the effects of such perturbation. For example, a method for using an implantable medical device is disclosed that involves delivering electrical stimuli to an efferent nerve associated with the selected organ. Afferent electrical activity is monitored during delivery of electrical stimuli to the efferent nerve, the monitored afferent electrical activity includes an indirect component of a compound action potential (CAP). A status of the selected organ is assessed based upon the indirect component. A determination is made as to whether to deliver therapy to the selected organ in response to assessing the status of the selected organ.