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Chapter 7: Functional description
Adjusting the calcium
dose if measured values
are outside the target
range
Delayed effect in case of
changed calcium dose
High calcium dose:
possible citrate
accumulation
Low calcium dose:
possible evidence of a
clogged membrane
7-24
Note
The concentration of the calcium solution used must be set correctly in
the System parameters / Select Ci-Ca data menu.
If the systemic ionised calcium measured is undesirably low, the
calcium dose should be increased. Accordingly, the calcium dose
should be reduced in case of elevated systemic ionised calcium values.
Even if the calcium dose can be adjusted in increments of 0.1 mmol/l,
the effect of such a change is so low that double increments, i.e., of
0.2 mmol/l, can also be used for fine adjustment. In the event of major
deviations of the measured systemic ionised calcium concentration, the
calcium dose can be readjusted in even greater increments,
if necessary.
Note
Unlike changes to the citrate dose, the effect of a change to the calcium
dose can be assessed only after some time has passed.
This is caused by the fact that the systemic distribution volume must first
develop a new balance. Depending on the efficacy of the CRRT
treatment and the size of the patient (or his / her distribution volume for
calcium), the first effects can already be seen after a few hours. The full
effect can, however, only be assessed after approximately one day.
This is particularly important to bear in mind if several equivalent
changes are made within short intervals because, in this case, there
may be an excessive response (e.g., hypercalcemia if the calcium dose
is increased repeatedly within short intervals).
If the calcium dose necessary for stabilising the systemic ionised
calcium is higher than 2.1 mmol/l, this might be indicative of a citrate
accumulation. The device alerts the operator to this fact when setting
the respective calcium doses and suggests a measurement of the total
calcium. For more information on citrate accumulation
(see chapter 7.3.2.5 on page 7-27).
If a calcium dose of less than 1.3 mmol/l is sufficient for the stabilisation
of the systemic ionised calcium, this may be indicative of a clogged
membrane with reduced permeability for calcium-citrate complexes.
Alongside the reduced elimination of calcium and a correspondingly
lower requirement for calcium substitution, an increased systemic
infusion of citrate and, after metabolism, alkalosis are to be expected. A
combination of low requirements for calcium substitution and metabolic
alkalosis can also be indicative of a clogged membrane. A clogged
membrane has severely restricted functionality and must be replaced
(restart treatment following replacement of the multiFiltrate kit).
Fresenius Medical Care multiFiltrate IFU-EN-UK 15A-2015
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