Artificial Lung Closer to Clinical Trial
Long-Term Problems continued...
The BioLung, however, does not use a mechanical pump, nor does
blood ever leave the body. A little larger than a soda can, it is implanted in
the chest. The patient's own heart pumps blood into the device, which is packed
with hollow plastic fibers perforated with holes so tiny that only gas
molecules can pass through them. As blood filters through the fibers, carbon
dioxide escapes through the holes and is replaced by oxygen from the
surrounding air. Then the blood may go directly back to the heart to be pumped
to the rest of the body, or it may take a spin through the patient's lungs
There are advantages and drawbacks either way: Directing blood
through the lungs may help filter out blood clots, because the lungs have a
natural ability to do so. Also, the fresh supply of oxygen to the lung tissue
may help heal it. But that puts a heavier load on the heart, raising the risk
for heart failure. By sending the blood directly to the heart instead, it is
possible for the artificial lung and the natural lungs to share in breathing.
But that could let clots enter the bloodstream.
The BioLung is not meant to be a lifelong replacement for
diseased lungs. At best, researchers hope to buy time for those awaiting a
transplant and let them live relatively normal lives while they wait, rather
than be tethered to a heavy life-support unit.
After nearly a decade at the drawing board, "We are looking
at what we consider final design changes," Merz says. Clinical trials may
get under way in one to two years. The National Institutes of Health recently
granted Bartlett $4.8 million to continue the research.
Early animal studies have been promising. In the latest study,
University of Texas researcher Joseph Zwischenberger, MD, tried out the BioLung
on sheep whose lungs had been badly burned by inhaling smoke. Six of the eight
sheep on the BioLung survived five days, whereas only one of six sheep on an
external breathing machine survived that long.