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Treatment parameters
CVVHDF
Blood flow
Ultrafiltration
UF goal
Cont. heparin adm.
Substituate
Dialysate
Temperature
Efficacy of CRRT
treatments
Effluent
Coagulation risk in CRRT
treatments
Fresenius Medical Care multiFiltrate IFU-EN-UK 15A-2015
13
Substituate pump
14
Scale 2
15
Substituate
16
Heater
17
Dialysate pump
18
Scale 1
19
Dialysate
Min.
10
Off / 10
Off / 50
Off / 0.1
Off / 600
Off / 600
Off / 35
The efficacy of CRRT treatments depends largely on the total volume of
formed filtrate.
In practice, the efficacy is determined by the applied volume or the
selected flows of substituate and dialysate. With the Pre CVVHDF,
Post CVVHDF, and Pre-Post CVVH combined treatments, the total
dose is distributed to both pumps that are used (e.g., the intended total
dose in Post CVVHDF 2000 ml/h is applied as 1000 ml/h substitution in
postdilution and 1000 ml/h dialysate).
It may be necessary to increase the prescribed total dose in treatments
with predilution to compensate for the reduction of efficacy caused by
predilution (see above).
Depending on the filter used, a reduction of the middle-molecular
clearance is possible if dialysate is used (see above).
The risk of coagulation in the extracorporeal blood circuit is different in
the individual CRRT treatments.
With postdilution, there is a haemoconcentration of the blood at the filter
outlet, depending on the ratio of the filtrate flow to the blood flow, and
on the patient's haematocrit. This is assumed to be the reason for the
shorter operating lives of the filters in Post CVVH compared to
Pre CVVH.
There is evidence that the coagulation activity is lower in dialysis than
in haemofiltration in predilution. It was revealed that the filter operating
lives are significantly longer in CVVHD than in Pre-Post CVVH, even if
the limitation of the filtration fraction to 20% in Pre-Post CVVH was
observed.
Chapter 7: Functional description
Max.
Resolution
500
10
1200
10
10,000
50
25
0.1
4800
50
4800
50
39
0.5
Unit
ml/min
ml/h
ml
ml/h
ml/h
ml/h
°C
7-9
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