An apparatus for vascular access devices such as syringes and guidewires placement devices capable of differentiating type of blood vessel penetrated by a cannula, including a chamber in flow communication with the cannula, the chamber being adapted to house a vacuum pressure to accelerate backflow of...http://www.google.se/patents/US6217558?utm_source=gb-gplus-sharePatent US6217558 - Apparatus for blood vessel type differentiation for syringes and guidewires placement devices
