FAQs:
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 thrombolytic effect. It chelates clotting parts and
biofilm. This process may result in a pink colorization of the extension
parts of the catheter, especially 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 20 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 example Tesio catheters) are hard to determine
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 until the patient is aware of (one of) the
side-effects, which are totally harmless.
A pre dialysis blood sample showing an excessive hypernatremia 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 efficiently
with saline and never use syringe or needle which was also used to
aspirate the lock. The publication below describes a case of hypernatremia
in combination with Citra-Lock™.
