electromyogram , temperature and heart rate measurements , which correlate to the dermatomal level and density of neural blockade , are obtained in a passive manner , i . e ., the patient is not stimulated or exposed to any sensor that requires an active conduction in order to make a measurement and no active patient participation or response is required . the measurements obtained provide objective and quantitative indications of , for example , epidural blockade with local anesthetics , thus , allowing objective real - time assessment of density and level of neural blockade .