Randomized, double-blind clinical trial to compare the efficacy of catheter sealing with saline, compared to low-dose heparin. 3,450 patients hospitalized at the Hospital Residencia Sant Camil, in Catalonia (Spain), will be randomized to each branch of study. The primary outcome will be the percentage of catheters removed due to obstruction in each branch of study. As secondary outcomes, the number of catheter-associated phlebitis, catheter-associated bacetrihemia, extravasation, and catheter loss will be measured. For the primary outcome, a superiority analysis will be carried out in terms of the percentage of obstructed catheters in each branch of the study.

Inclusion Criteria:

• Patients older than 18 yo, admitted to the Hospital Residencia Sant Camil
• Patients with at least one peripheral venous line for discontinuous treatment, which has not been channeled in a medical emergency situation.
• Written informed consent

Exclusion Criteria:

• Allergy to heparin
• Patients treated with unfractionated sodium heparin.
• Patients in dialysis
• Patients with a venous catheter indicated for diagnosis tests.
• Patients with a venous catheter indicated for blood transfusion
• Severe heparin-induced thrombocytopenia in recent months
• Active uncontrollable bleeding during admission
• Brain aneurysm or dissecting aorta, except in association with corrective surgery.
• Confirmed / suspected cerebrovascular hemorrhage
• Severe uncontrolled hypertension
• Severe alterations in platelet coagulation <30,000, TP> 1.7 APTT ratio> 1.7 ratio.
• Patient included in another clinical trial with drugs or procedures that may affect the patency of venous catheters.

IPD (without personal identification data) could be shared by requirement from other researchers after the end of the study, and only for research proposels and previous approval of promotor center of the study (CSAPG). Anyway, Spanish and European Union legal policy about data protection will strictly be followed (IPD will not be transferred outside European Union).

After publication of main results of the study

IPD will be shared only for scientific research purposes and following the Spanish and European Union normative law about data protection. The requirements will be directed to the IP of the study. The IP will evaluate the request to verify and evaluate the data that is requested and the purposes for which it is requested. Next, the IP will transfer the request to the promotor center the study for the final decision.