A small, portable, constant withdrawal device is connected to tubing, including a catheter, whose internal walls are coated with heparin. The catheter is inserted intravenously through a disposal needle into a subject such as a human being. The subject may then move about for a selected period when blood...http://www.google.de/patents/US4008717?utm_source=gb-gplus-sharePatent US4008717 - System for continuous withdrawal and analysis of blood
