The open end of a catheter is inserted in the blood vessel of a patient. The catheter is connected by hollow tubing to a physiologic pressure transducer. The tube is filled with an intermediate pressure-transmitting fluid such as a physiologic saline solution. An infusion device between the patient and...http://www.google.sh/patents/US4431009?utm_source=gb-gplus-sharePatent US4431009 - Apparatus for measuring blood pressure
