Chemotherapy treatment or the administering parenteral feeding requires permanent venous access during weeks, months or perhaps years. To have available an adequate venous access while treating gravely ill patients is fundamental in order to guarantee the perfusion of fluids blood transfusions administration of medicines, to supply intravenous feeding, to draw blood samples, etc. In this article, which will have a follow-up which concentrates on proper handling, the authors expose the reasons why subcutaneous venous access implants and used as well as how to deal with one of their main complications; extravasation. A bibliography will accompany the follow-up article.