Study Design:

This study has a prospective, open, randomized, unblinded, group-sequential design. Study initiation will be proceeded by a program of education and training for all the nurse participants to ensure proper handling of both systems and standard insertion and maintenance techniques for both catheter systems. This standardization will include disinfection of the skin and access ports as well as fixation of the catheter using a standard transparent dressing. Also training will be given on best practice procedures for removing the catheter, on sterile technique for culture of the catheter tip and on proper data capture methods using the Clinical Report Form (CRF). All the nurses participating in the study will certify their attendance to all trainings, their acceptance of the present protocol and their voluntary participation by signing the Participant Registry at the conclusion of the trainings. They must give their full names as well as personnel and unit numbers, which will then be used to constitute the Investigating Group as well as to protect identities while providing a traceable record of participants.They must have passed a training examination consisting of 10 questions related to the study with a passing mark of at least 80% questions correct. The study will be preformed in three medical and surgical units of the University Clinical Hospital San Carlos of Madrid, which is affiliated with the Madrid Health Service, and is an integral part of the Autonomous Region (Community) of Madrid.Trainings and other activities related to the study will not begin until formal approval of the protocol by the Ethics Committee (abbreviated CEIC in Spanish) of this hospital. In order to reduce variability in the study, all catheters will be inserted using only 70% alcohol for disinfection of the skin and access ports.

Following manufacturer recommendations, all three-way taps (in USA, 'stop cocks') with extension tubes will be changed every 72 hours and split-septum connectors will be changed every 8 days. In order to calculate colonization rates in both catheter systems and the correlation of colonization with clinical complications, tip cultures will be taken of a representative sample of catheters in each arm. This process will be randomized and will coincide with catheter withdrawal. Additionally all catheters removed because of pain, phlebitis or suspected infection will have their tips cultured. Our sample size target for cultured tips is 380 in total. During the study, six nurse-coordinators, with experience in intravenous therapy and special training in study procedures, will actively supervise all aspects of catheter management and will report to the Principal Investigator (PI) on a regular basis. They will ensure the randomization processes are followed and that all procedures established by the Protocol, as well as of the correct filling out of the CRF, are rigorously adhered to. In order to accomplish this they will make daily inspections of all catheters included in the study, will check each item on each CRF daily to ensure all are properly and promptly filled out and will follow the catheter tip cultures to certify that the results are registered on the CRFs. The coordinators will not otherwise intervene in patient care. Any decision related to placing or removing a peripheral catheter for any cause, all decisions on the care and maintenance of the catheter system, and all treatment decisions related to the patients will be the sole responsibility of the doctors and nurses caring for the patient. Nurse-coordinators and/or the PI will not intrude in any way in these decisions. An intermediate analysis will be done when each unit reaches 166 catheters inserted. This analysis will allow us to confirm the power calculation of the study and determine final sample size targets. All patients admitted to one of the three participating units, who needs a peripheral venous catheter of gauge size18 G, 20 G or 22 G, will be evaluated for potential inclusion in the study. Using the CRF a determination of eligibility will be made and then study purpose and requirements will be explained in layman's terms to the patient by his primary nurse. If accepted into the study patient informed consent will be obtained. Informed consent may be verbal on the condition that it is witnessed by one of his or her relatives and is documented in the CRF. After this the patient will be randomized to the experimental group (closed system) or to the control (open system).