An apparatus for use in cannulation of blood vessels which includes an ultrasonic flow sensing assembly. The assembly includes inner and outer elongated electrically conducting tubular members which are separated by an electrical insulator. A piezoelectric transducer capable of generating and receiving...http://www.google.com.au/patents/US5259385?utm_source=gb-gplus-sharePatent US5259385 - Apparatus for the cannulation of blood vessels
