An artificial implantable lung that uses tiny hollow fibers and
the heart's own pumping power to oxygenate blood is showing promise
in pre-clinical studies, and may reach clinical trials in about
a year for lung failure patients awaiting a lung transplant. Meanwhile,
a new survey of lung transplant program directors shows that such
a device is badly needed.
update on the new device's progress and prospects, and results from
the survey, will be presented here on June 13 by University
of Michigan surgeon and life support pioneer Robert Bartlett,
M.D., at the annual meeting of the American
Society for Artificial Internal Organs. Bartlett developed the
lung with colleagues from the U-M Health System, the U-M College
of Engineering, the University of Texas, Northwestern University
and MC3 Corp. of Ann Arbor, MI.
At the ASAIO
meeting, he will discuss recent design advances that have improved
blood flow through the compact chamber, and encouraging results
from week-long tests in sheep. He will present plans for the next
phase of testing, supported by a new $4.8 million federal grant,
which will evaluate the device's ability to totally support sheep
lung function for 30 days or more. And he will present results from
the survey that shows that the majority of major lung transplant
centers would want to participate in an initial clinical trial once
pre-clinical testing is complete.
presentation will be part of a larger ASAIO session on artificial
lung technology that he will chair. The session will also focus
on a University of Pittsburgh device, called IVOX, that is placed
within a vein and supports 50 percent of lung function. The U-M
lung attaches to the pulmonary artery, can be used in or outside
the body, and replaces 100 percent of lung function.
generation of long-term, bridge-to-transplant implantable artificial
lungs is on the verge of reaching the patients who need it most,
and have no other options," says Bartlett, a professor of surgery,
director of critical care and head of the extracorporeal life support
team at UMHS. "We've overcome the technical hurdles and now
must confirm that it can truly take over for failing lungs for a
longer time, and with less risk, than current life-support technology.
As transplant program leaders tell us, we've never needed these
More than 13
million Americans have chronic respiratory diseases, such as pulmonary
fibrosis and emphysema, for which the only effective treatment is
lung transplant. But the shortage of donated lungs means that patients
sick enough for a transplant wait an average of two years for an
organ, and 80 percent die before receiving one. Currently, 4,000
Americans are waiting for a lung or heart-lung transplant, a number
that rises sharply each year. About 1,000 lungs are transplanted
in the U.S. each year, alone or in tandem with a heart transplant.
to keep lung failure patients alive during a crisis has steadily
improved. But the search for a long-term option to "bridge"
lung disease patients to transplant has been frustrating.
In the 1980s,
Bartlett led the team that developed the extracorporeal
membrane oxygenation, or ECMO, machine now used in intensive
care units worldwide to circulate and oxygenate the blood of desperately
ill trauma, burn, infection and organ failure patients. Though he
and his UMHS colleagues have built the world's most experienced,
successful ECMO team, they still realize that ECMO is best for short-term
use to get patients through a crisis.
use can be risky and costly, as can long-term use of mechanical
ventilators, which have been used for decades to help patients whose
own lungs are damaged. Half of all patients put on ventilators for
acute lung problems die before their crisis is over. And those who
survive ventilator or ECMO use have a higher risk of dying before
or after a lung transplant.
The U-M artificial
lung was recently shown to produce better survival and less lung
injury than a conventional ventilator in five-day tests on damaged
sheep lungs. The study was led by Bartlett, UMHS pediatric surgeon
Ronald Hirschl, M.D., and surgery fellow Jonathan Haft, M.D.
results have been improved by a new design for the device, based
on sophisticated computer modeling and prototyping done by a team
led by U-M bioengineering professor James Grotberg, Ph.D.
have reduced the device's size, made it more flexible, and improved
the flow of blood, thereby enhancing the lung's performance and
reducing the risk of clotting and infection.
lung uses no mechanical pump, instead relying on the heart's own
pumping force to send blood from the pulmonary artery into the chamber,
past the hollow fibers with tiny micropores that exchange oxygen
from the air with carbon dioxide from the blood. The lack of a pump
cuts costs and reduces damage to blood cells.
can then flow back to the pulmonary artery and circulate through
the lungs for clot-filtering and other benefits, or directly into
the heart's left atrium before being sent to the body," explains
his colleagues envision that the device could eventually help lung
transplant candidates stay alive and mobile for six months or more,
outside the hospital, and allow them to stay healthy enough to remain
at the top of the transplant list. It may also prove suitable for
burn and smoke inhalation patients, victims of near-drowning, and
those with traumatic injuries.
A $4.8 million,
five-year grant from the National Institutes of Health's new Institute
of Biomedical Engineering will support further development of the
device, and pre-clinical and clinical trials.
are made by Michigan Critical
Care Consultants, Inc., or MC3, a firm founded by U-M bioengineering
alumni. Pre-clinical studies are being done by Bartlett's team at
UMHS, and a team led by Joseph Zwischenberger at the University
of Texas Medical Branch in Galveston. Northwestern engineers have
contributed to the design.
for clinical trials, Haft led a survey of transplant program directors
at some of the nation's largest lung transplant centers. The findings
suggest widespread interest and anticipation, with the vast majority
saying they'd want to participate, and a majority saying that animal
trials of one month or less, in a few dozen animals, would be sufficient
as final pre-clinical testing.
overwhelmingly said that patients with idiopathic pulmonary fibrosis,
a mysterious and deadly scarring of the lungs with no known cause,
would be the best candidates for the first clinical trials. They
typically have the highest waiting-list death rate, and their disease
progresses rapidly without responding to therapy. A Phase I trial
of less than 30 participants was considered reasonable, with a goal
of bridging 60 percent of participants to transplant.
the lung transplant system currently allocates organs based only
on waiting time, size of organ needed and blood type, a clinical
trial of an artificial lung as a bridge to transplant would require
a change to allocation policy for participants. The survey found
support for this shift, which would prioritize transplants for those
on the artificial lung, among 67 percent of transplant program directors.
Still others voiced partial support.
use for the artificial lung would be in patients who receive a sub-optimal
lung transplant, and need lung support after their transplant to
determine if the new lung will function.
on this release
Thanks for your interest in artificial lung research at the University
of Michigan Health System. The device developed by U-M doctors and
engineers still needs to be tested further in animals, before any
clinical trial involving human participants can take place.
If the long-term
animal studies are successful, the U-M team will then ask the U.S.
Food and Drug Administration for permission to do a trial involving
people. But, they have not decided which lung diseases to study
in the initial clinical trial, nor which patients with those diseases
will qualify. Neither have they established a list of patients who
want to be considered for the first clinical trial. If you are interested
in learning more about the progress of the U-M artificial lung,
please check back at the UMHS web page, www.med.umich.edu,
later this year.
If you would
like to learn about the UMHS lung transplant program, or be evaluated
for possible lung transplant listing at UMHS, please call (734)
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