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

Surg Gynecol Obstet. 1976 Mar;142(3):373-6.


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.

MeSH terms

  • Animals
  • Blood Coagulation* / drug effects
  • Catheterization / methods*
  • Dogs
  • Dose-Response Relationship, Drug
  • Female
  • Heparin / administration & dosage*
  • Heparin / pharmacology
  • Humans
  • Injections, Intravenous*
  • Male
  • Prothrombin Time
  • Rabbits
  • Sodium Chloride / administration & dosage
  • Thromboplastin


  • Sodium Chloride
  • Heparin
  • Thromboplastin