Heparin-lock maintenance with ten units of sodium heparin in one milliliter of normal saline solution.

A rapid increase in use of heparin-lock to maintain patency of established intravenous pathways for intermittent and emergency intravenous injections of drugs has given rise to questions concerning the necessary heparin-saline solution concentration to prevent coagulation and minimize or avoid systemic effects of heparin on blood clotting. A series of experimental and clinical studies followed by clinical observations and evaluation have shown that a concentration of 10 U.S.P. units of sodium heparin per milliliter of normal saline solution will maintain patency of heparin-locks without affecting the clotting time, prothrombin time or activated partial thromboplastin time. A procedure of flushing the heparin-lock with 1 milliliter of the recommended heparin-saline solution following each intravenous injection of medication or every eight hours, if medications are not given more frequently, is suggested.