FAQ

Citra-Lock™ is a catheter lock solution for central venous catheters and is used as a lock in the catheter between two treatments to keep the catheter open and unclotted. It is placed in the catheter after a treatment and it must be aspirated before the next treatment.

The main component is high concentrated tri sodium citrate. The solution is adjusted for pH.

Citra-Lock™ replaces heparin as a catheter lock. The two main problems using (heparine locked) central venous catheters are thrombosis and infection. It is proven in in vitro and in in vivo studies, as well as in clinical practice, that a high concentrated citrate solution like Citra-Lock™ has a broad spectrum antimicrobial and antiyeast activity. Citra-Lock™ also has a thrombolitic effect. Citra-Lock™ even prevents formation of biofilm.

The clinical (harmless) side-effects which are described and mentioned from clinical practice are dysgesia and parathesias. These side-effects disappear within 1 minute and are a sign that the catheter lock volume was overdosed. Decreasing the volume with 0,1 mL for the next instillation will solve the problem in most cases. If the patient still complains, decrease the lock volume again with 0,1 mL, untill the the patient doen't complain anymore.

If Citra-Lock™ is used according the instructions in volumes suitable to catheter lumens, there is no reason to expect systemic effects from such a small volume of citrate. In relative big catheters like Ash Split, Tesio(MedComp) or Opti-Flow (Bard) the injected volume is app. 4 mL. Because citrate is metabolized to bicarbonate (1:3) this small volume of maximum 4 ml (= 6,4 mmol/l) won't even result in any acid-base disorders.

After dialysis, first the catheter is flushed with saline (5 to 10 mL per lumen). Then, both lumens are instilled with Citra-Lock™. The lock has to be injected slowly to be placed effectively in the catheter lumen (this counts for any catheter lock, also for heparine). The volume is determined by the presciption of the catheter manufacturer.

The volume of the internal catheter lumen can be decreased for several reasons:

• a thrombus in the proximal catheter tip (catheter still functions on sideholes);
• biofilm;
• a catheter is shortened (like Tesio and someother catheters).
• overdosed prescribed locking volume (see picture). It is known and tested that several catheter manufacturers overestimate the catheter lock volumes.

Citra-Lock can slowly be injected into the patient without any risk, because there is a decrease of the initial level of citrate (46,7%) in the interdialytic period, due to leakage and diffusion. This is described in several publications (see below). Therefore the concentration of the injected citrate is even more harmless. Citra-Lock™ has no systemic effects after injection (see question 5).

Citra-Lock™ has a thrombolitic effect. It chelates clottingparts and biofilm. This process may result in a pink colorization of the extensionparts of the catheter, specially in those catheters which are in situ for a relatively longer period of time.
Leakage of Citra-Lock™ is also a reason for the colorization.

According European regulations Citra-Lock™ is CE-registrated as a medical device class 2B. Therefore it can be sold in any country where CE-registration is approved. Some countries outside the EU also accept the CE mark.

Our company has contracted several distributors. Citra-Lock™ is distributed worldwide.

Each box with Citra-Lock™ contains 10 vials.

In this case first check if patients were aware of any side-effects. Clinical experiences showed that probably nobody was. That's a sign that an insufficient volume Citra-Lock™ was injected. We know from tests that prescribed locking volumes often are over- or under estimated, which will lead to inefficient locking of catheters. Especially the catheters which can be adjusted for length (for exmaple Tesio catheters) are hard to determin the right locking volume. Injecting a lock below the sufficient actual catheter volume will cause clotting and dilution of the catheter. This decreases the effect of Citra-Lock™. In cases like this, increase the injected volume by 0.1 ml every treatment untill the patient is aware of (one of) the side-effects, which are totally harmless.

A pre dialysis blood sample showing an excessive hypernatraemia shows up when the catheter, previously locked with Citra-Lock™, wasn't efficiently flushed with saline. Even very small remains will cause a disturbed outcome of a natrium analysis. To avoid this flush the catheter efficently with saline and never use syringe or needle which was also used to aspirate the lock. The publication below describes a case of hypernatraemia in combination with Citra-Lock™.