An esophageal transducer measures pressure due to esophageal contractions. The transducer is inserted into the esophagus at the end of a catheter. The transducer is fully contained within a housing at the end of the catheter and is capable of measuring pressure variations at all points about its entire...http://www.google.es/patents/US3939823?utm_source=gb-gplus-sharePatente US3939823 - Esophageal transducer
