An electronic method and apparatus for automatically determining systolic and diastolic blood pressure and heart rate by accurately detecting, verifying and evaluating the full stream of korotkoff sounds produced as electrical signals from a microphone in a cuff occluding the brachial artery of a patient....http://www.google.de/patents/US4313445?utm_source=gb-gplus-sharePatent US4313445 - Electronic sphygmomanometer
