Condition category
Injury, Occupational Diseases, Poisoning
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Dialysis removes substances from the blood to avoid uremia - a syndrome that intoxicates the patient by the accumulation of compounds that are usually excreted in the urine. There are more than 4000 of such substances but we currently measure only a few of them. Special filters in dialysis machines that allow those substances to be removed from the blood to the dialysate, the ‘water’ that is used to wash the blood. These dialysis membranes usually only allow small substances to travel from the blood of the patient to the dialysate, such as urea, sodium, potassium and phosphorus. Bigger molecules can only be removed from the blood by dialysis membranes with a larger pore size. Hence, there might be a disadvantage in using large pores as the patient would lose important proteins like albumin. The aim of our study was to compare two dialyzers (the AV 1000S and the EMiC2) in their ability to eliminate small and bigger molecules. Both dialyzers are equal in membrane surface area and membrane material, but differ in their membrane pore size. The EMiC2 dialyzer has a larger pore size than the AV 1000S. We further aimed to investigate whether the dialyzer with the larger pore size would leak albumin.

Who can participate?
Every critically ill patient over the age of 18 with acute kidney injury undergoing extended dialysis with the GENIUS 90 system.

What does the study involve?
Every patient received two consecutive extended dialysis sessions starting in a random order with either the EMiC2 or the Ultraflux AV 1000S filter, followed by a treatment with the other dialyser. Levels of the molecules beta2-microglobulin, cystatin c, albumin, creatinine and urea were measured before and after 0.5, 5.0 and 10 hours of dialysis.

What are the possible benefits and risks of participating?
Dialysis with highly permeable membranes could lead to a mild protein loss which in itself does not present an increased medical risk. We monitored every patient’s nutritional status carefully and tailored the individual nutrition to the patient’s need. There might be a benefit of removing larger substances from the blood of critically ill patients but the potential effect, if existent, will not be of clinical importance for the individual patient.

Where is the study run from?
The intensive care units of the Hannover Medical School (Germany).

When is the study starting and how long is it expected to run for?
Patients were enrolled between May 2009 and May 2012.

Who is funding the study?
Investigator-initiated trial.

Who is the main contact?
Jan T Kielstein

Trial website

Contact information



Primary contact

Prof Jan T Kielstein


Contact details

Department of Nephrology and Hypertension
Medical School Hannover
Carl-Neuberg-Str. 1

Additional identifiers

EudraCT number number

Protocol/serial number

Hannover Medical School, Germany, protocol # 5307

Study information

Scientific title

Comparison of middle molecule clearance and removal between a new high cut-off dialyzer to an established dialyzer - a clinical cross-over comparison in extended dialysis


Study hypothesis

We aimed to evaluate the efficiency of a new dialyzer comprised of a new polysulfone membrane and a bigger pore size in regard to its ability to eliminate beta-2 microglobulin (molecular weight 11.8 kDa), an excellent surrogate for middle molecules as well as its properties in terms of albumin (molecular weight 65 kDa) loss.

Ethics approval

Hannover Medical School, Germany, 27/04/2009, ref: 5307

Study design

Randomized cross-over comparison

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Acute kidney injury, renal replacement therapy


In this prospective randomized cross-over trial every participating patient received two consecutive extended dialysis sessions starting in random order either with the EMiC2 or the Ultraflux AV 1000S dialyser followed by a treatment with the other dialyser. The duration of treatment for each patient was two days.

Intervention type



Not Applicable

Drug names

Primary outcome measures

1. Dialyser clarance of middle molecules
2. Total amount of middle molecules in the combined spent dialysate and ultrafiltrate dialyzer clearance measured 30 min after start of treatment for the quantified substances according to equation 1 using the patients’ hematocrit level (Hct) at the time of clearance sampling.
Eq. 1: Kplasma = QB x (1 – Hct/100) x ((Cart – Cven)/Cart)
3. Reduction ratio (RR) determined for beta2-microglobulin, creatinine, cystatin c and urea. Therefore, blood samples will be collected right before the start (Cpre) as well as at the end (Cpost) of the treatment. Calculations of RR executed according to equation 2.
Eq. 2: RR = (Cpost – Cpre)/Cpre x 100
Samples of the total spent dialysate will be drawn at the end of the treatment.

Secondary outcome measures

Albumin loss
Total loss of albumin by adding the albumin values in the total spent dialysate and ultrafiltrate. For concentrations below the detection limit of 1.1 mg/dl, an albumin concentration of 1.1 mg/dl was assumed.
Eq. 3: Alb = Calb(dialysate) x Vdialysate + Calb(ultrafiltrate) x Vultrafiltrate

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Males and females
2. Aged > 18 years
3. Patients in the intensive care unit suffering from acute kidney injury [stage Acute Kidney Injury Network (AKIN) III], i.e. need for renal replacement therapy
4. Treatment using the 90 L GENIUS batch dialysis system
5. Signed consent

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Pregnant and nursing patients
2. Patients participating in a different study (other than observational)
3. All conditions deemed to justify exclusion by the recruiting physician

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Department of Nephrology and Hypertension

Sponsor information


Medical School Hannover (Germany)

Sponsor details

c/o Prof Jan T Kielstein
Department of Nephrology and Hypertension
Carl-Neuberg-Str. 1

Sponsor type




Funder type


Funder name

Fresenius Medical Care (Germany)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes