BACKGROUND:

Central venous catheters (CVCs), originally introduced for short-term dialysis, have become an acceptable form of permanent vascular access.CVCs evolved as a bridge to optimal management in hemodialysis (HD) patients who await arterio-venous fistula (AVF) maturation as well as a solution for patients who have no alternate access.Despite great advances, two major causes of catheter loss continue to plague sustained effective HD treatment due to catheter-related bloodstream infection (CLABSI).

The colonization of the intraluminal space through the catheter hub or following a bacteremia episode is accepted as the more likely pathogenesis of CLABSI for long-term catheters (intraluminal hypothesis) . Biofilms that harbor

microorganisms are demonstrated on external and internal surfaces of indwelling catheters for both cuffed and uncuffed catheters as early as 24 h after their insertion . These biofilms are mostly responsible for the treatment failures in CLABSI, because their protein–fibrin ultrastructure prevents optimum antibiotic exposure, providing a niche for the microorganisms.

Infection related to central venous catheters is also associated with adverse health outcomes and high health care costs.Indeed, catheter-related sepsis is one of the

most common causes of death in patients undergoing hemodialysis.

PURPOSE OF THIS STUDY:

To prevent CLABSI, various pharmacological agents are instilled into the arterial and venous ports of hemodialysis catheters. Heparin has been the traditional locking solution  widely used.

Recombinant tissue plasminogen activator (rt-PA) has been used primarily to treat catheter thrombosis. Although the relatively high cost of rt-PA and its theoretical potential to cause bleeding ,it has advantage of significantly improved blood flow rates, lower venous pressures, and fewer complications. Antibiotic locks demonstrated a reduction in CLABSI; however, there is growing concern that their overuse enables the development of antibiotic resistance., Wong et al.studied the effects of bicarbonate on blood coagulation. They suggested that removing bicarbonate chelated calcium ions from the coagulation pathway

required calcium as a cofactor. In doing so, the bicarbonate-mediated chelation of calcium ions indirectly inhibited the  conversion of fibrinogen to fibrin, leading to decreased clotting.

Sodium bicarbonate is inexpensive, safe and effective method in preventing HD catheter loss due to clot formation . NaHCO3 has been shown to inhibit bacterial proliferation by decreasing bacterial adherence and preventing biofilm formation.

However, evidence supporting the use of various locking solutions in HD catheters-mainly in non tunnelled non cuffed type - to achieve these objectives is limited.