The effect of pre-versus postdilution and pore size on the clearance of mid size mocules.

In patients with severe shock caused by sepsis or SIRS, high volume
hemofiltration during 6-8 hours has a possible positive effect on stabilisation
of the circulation and on survival. This effect is found in patients with
septic shock with or without renal failure. The circulation in patients after
cardiac arrest is often unstable due to a systemic inflammatory response.
Laurent compared patients after out of hospital cardiac arrest (ROSC < 60min)
treated with the standard therapy (therapeutic hypothermia was not common
practice in the study period), treated with HVHF and treated with HVHF and
hypothermia. There was a significant better survival in both HVHF groups
compared with standard treatment.
In the mentioned studies HVHF was given in dose variable from 4-8 lietrs/hr. In
the studies with the higher dosis, the substitutionsfluid are administered in
predilutionmodus.
The are large differences in the studies in dosis and in pre- or postdilution
modus. Dosis is therefore not comparable in the different studies.

The primary goal is investigate the method to achieve the most effective
clearance od midmoecules in the first 6 hours of HVHF.
The secondary goal is to determine to wich proportion the clearance of
midmolecules due to proteinprecipitation declines in time.

Prospective randomized controlled trial with patients after cardiac arrest,
treated with hypothermia.
Patients will be randomized for HVHF with the conventional filter
(cellulose-triacetate, cut-off 60.000 D), high permeable cellulose-triacetate
filter (cut-off 100.000 D). In both groups patients will be ramdomized for
modus A, B or C

Modus Bloodflowml/min SubstitutionflowPOST ml/u SubstitutionflowPRE ml/u Extra
UF
A 240 4100
0 0
B 240 3000
1500 0
C 240 0
5900 0

Hemofiltration with one of the earlier mentioned filters in 1 of the 3 modi (A,
B, C)

The studie patients will receive a CVVH catheter in the vena femoralis or vena
jugularis. Theoretically, complications of the insertion of a CVVH catheter are:
· arterial punction and hematoma
· Pneumothorax (only in the vena jugularis position)
The chance of these complications is small in our hospital.
During the first 24 hours, there will be blood and ultrafiltratesamplings. The
arterial bloodsamples will be drawn from the arterial catheter, already in
place in this catergory of patients. The patient will not notice this at all.
The postfilter bloodsamples will be taken at he side of the hemofiltration
machine, as will be done for the ultrafiltrate monsters. There is no burden for
the patient. Everey sampling of blood will take 19 ml of bloof=d from the
patient.