Urology & Kidney Disease News - Cleveland Clinic

22 Urology & Kidney Disease News
Renal Failure
Prototype bioartificial kidney membrane – photographed at 50x
with interference contrast microscopy. Each rectangular window
consists of nearly 1,500 nano-scale slit pores measuring 9 nm
wide. The small dimension of the pore is manufactured with a
tolerance +/- 1 nm and each square centimeter holds more than
3.8 million individual pores.
A New Approach to Antibiotics in the ICU
William Fissell, MD
Acute renal failure is a common complication of severe illness
and affects patients with medical and surgical diseases.
Many patients with acute renal failure die of infection, and
almost all are treated with antibiotics at some point during
their illness. Selecting a drug dose to prescribe for a patient
in the ICU is challenging, as almost all of the physiology that
controls drug elimination is abnormal in critically ill patients
with renal failure. Plasma protein binding, blood flow to the
liver and other vital organs and kidney function are altered.
At the American Society of Nephrology’s Renal Week 2009,
we showed that present antibiotic dosing schemes may not
New Membrane for Bioartificial
Kidney Shows Improvements
Over Polymer Membranes
William Fissell, MD
Working with engineers at the University of California, San
Francisco and Pennsylvania State University, we have developed
the first entirely new membrane for renal replacement
since the high-flux polysulfone dialyser. The membrane is
made from a silicon chip, just like a microprocessor, and
has pores that are shaped like slots, rather than round holes,
mirroring the elongated slot-shaped pores that have evolved
in many animals. We tested the novel membranes and
predicted the membrane’s benefit would be in permeability
— letting salt and water through, but retaining proteins —
and the predictions were correct. In a recent paper, Andrew
Zydney, Chair of Chemical Engineering at Pennsylvania State
University and a close collaborator on the bioartificial kidney
project, demonstrated that the novel membranes also were
able to discriminate between smaller molecules and larger
molecules more effectively than membranes with round
pores. This finding was borne out by experiments showing
that the new membranes could retain albumin and other
large proteins while passing 2-microglobulin, a molecule
that accumulates in renal failure.
For references, please email the editor.
always be adequate for patients on continuous dialysis. In an
exciting innovation, we were able to use a spent dialysate —
a waste product — to measure the patient’s blood antibiotic
levels. This is an inexpensive way to bypass complicated and
expensive sample preparation for HPLC and avoids drawing
even more of the patient’s blood — always an issue in the ICU.
For references, please email the editor.