Source:http://linkedlifedata.com/resource/umls/id/C1138873
UMD: Instruments designed to measure the quantity of energy per unit of time (i.e., power), usually in watts. Power meters typically include detectors, electronic circuitry, and displays with characteristics appropriate to measure a particular type of energy (e.g., direct-current, alternating-current, and/or radio-frequency electric power; ultrasonic power) within a range of power values. Power meters are typically used to measure the power output of medical devices (e.g., diathermy units, warmers, ultrasonic physiotherapy units) or to determine the strength of radiation at a given point.