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Chapter 7: Functional description
7.3.2.2
Adequate anticoagulation in the extracorporeal blood circuit
Required citrate dose
Adequate citrate
anticoagulation in the
extracorporeal blood
circuit
Adjusting the citrate dose
7-22
The citrate dose is defined as the volume of citrate ions (in mmol)
infused per litre of processed blood. As a result, its unit is that of a
concentration. The citrate dose can be set within a range of
2 to 6 mmol/l.
In many patients, the required regional anticoagulation for a Ci-Ca
CVVHD is achieved with a citrate dose of 3.5 to 4.5 mmol/l.
With Ci-Ca postCVVHDF, the use of a higher citrate dose is
recommended. Here, a starting value of 5.0 mmol/l citrate dose is
appropriate. This change, in comparison to Ci-Ca CVVHD,
compensates for the effects of the haemofiltration component of Ci-Ca
postCVVHDF on the acid-base state (see chapter 7.3.2.4 on
page 7-25) and inhibits a premature increase in the concentration of
ionised calcium following infusion of the calcium-rich substitution fluid at
the postdilution stage.
The citrate ion concentration of the citrate solution used is required to
calculate the applied citrate flow from the blood flow and the set citrate
dose.
Note
The concentration of the citrate ions in the citrate solution used must be
properly set in the setup of the device.
The efficacy of the citrate anticoagulation is typically checked by
determining the ionised calcium in the extracorporeal blood circuit.
Lowering values to below 0.35 mmol/l of ionised calcium in the
extracorporeal blood circuit (downstream of the filter) is associated with
only a minor risk of coagulation in the extracorporeal blood circuit. For
Ci-Ca postCVVHDF, lowering values slightly more has the benefit of
inhibiting a premature increase in the concentration of ionized calcium
following infusion of the calcium-containing substitution fluid at the
postdilution stage.
If the ionised calcium measured in the extracorporeal blood circuit is
lower than the required value, the citrate dose should be reduced.
Accordingly, the citrate dose should be increased if the ionised calcium
in the extracorporeal blood circuit is reduced insufficiently.
The citrate dose can be set in increments of 0.1 mmol/l. This increment
enables fine adjustment in the event that there is a very small deviation
from the target range.
After the citrate dose has been readjusted, the new setting can be
checked as early as a few minutes later and readjusted if necessary.
The extracorporeal fill volume should be completely exchanged at least
once, and the required time therefore depends on the set blood flow. All
kits for Ci-Ca treatments permit a representative check after 5 minutes
even in case of a low blood flow of 80 ml/min.
Fresenius Medical Care multiFiltrate IFU-EN-UK 15A-2015
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