In June, Ottawa Hospital in Canada announced its first organ
transplant in recent history from a patient who hadn't been
classified as brain-dead, but whose heart had stopped - so-called
"donation after cardiac death" (DCD). By switching
to this definition of death for transplant purposes, doctors
hope to increase the number of healthy organs available and
the number of potential donors from which they can be harvested.
For example, the Australian Health Ethics Committee (AHEC) is
considering recommending legislation to enable more DCDs, as
part of a drive to turnaround Australia's flagging organ donation
rates. A similar shift is taking place in the US, where a limited
number of DCDs already take place. There, the number of DCD
kidney transplants has increased fivefold since 1995 to over
500 in 2004, and numbers are expected to increase sharply over
the next decade.
http://www.newscientist.com/article/mg19125633.400-not-braindead-but-ripe-for-transplant.html
On a cold Canadian night, Janet, a 20-year-old aspiring athlete,
rolled her car. Her seat belt slipped up around her neck, adding
to a plethora of injuries, including brain damage so severe
that she had to be kept permanently anaesthetised, and spinal
damage that would likely lead to quadriplegia.
For 25 days Janet (not her real name) lay in intensive care.
One specialist declared her case hopeless, and recommended switching
off life support. Had that happened, first her heart would have
stopped, and several minutes later her brain activity would
have ceased. Yet although Janet was a card-carrying organ donor,
in many countries her organs wouldn't be used. This is because
doctors would normally wait to confirm that she was brain-dead
(see "Redefining death"). In the time it takes to
do that her organs would have been irreparably damaged.
For this reason, organs for transplant usually come from patients
with brain injuries so severe that brain death is determined
before the life support that keeps their hearts and lungs functioning
is removed, enabling their organs to be kept in good condition
until the moment they are harvested. Such organs are in critically
short supply.
Now, however, this situation is changing. In June, Ottawa Hospital
in Canada announced its first organ transplant in recent history
from a patient who hadn't been classified as brain-dead, but
whose heart had stopped - so-called "donation after cardiac
death" (DCD). By switching to this definition of death
for transplant purposes, doctors hope to increase the number
of healthy organs available and the number of potential donors
from which they can be harvested.
For example, the Australian Health Ethics Committee (AHEC) is
considering recommending legislation to enable more DCDs, as
part of a drive to turnaround Australia's flagging organ donation
rates. A similar shift is taking place in the US, where a limited
number of DCDs already take place. There, the number of DCD
kidney transplants has increased fivefold since 1995 to over
500 in 2004, and numbers are expected to increase sharply over
the next decade.
The driving force behind this change is the worldwide shortage
of organs (see "The crisis in organ donation"). Last
week, doctors at the World Transplant Congress in Boston, Massachusetts,
heard how the pool of available organs in the US could increase
by up to 20 per cent if DCD was adopted more widely - enough
to treat many of the estimated 6000 people in the US who die
each year while on organ waiting lists. In the UK, strong government
support has helped swell numbers of DCDs more than sixfold in
the last 15 years, to 120 in 2005.
“The pool of available organs in the US could increase
by 20 per cent if donation after cardiac death was widely adopted”
In light of this, it is all the more surprising to discover
that the medical community is divided about the ethics of DCD.
What's more, donor-card holders, far from consenting to the
new practices, are blissfully unaware of the seismic shift in
organ collection procedures.
"Doctors are very pragmatic," says Christopher Doig,
a critical care specialist at Canada's Foothills Hospital in
Calgary, Alberta. "But there is something inherently bothersome
about changing the way we are going to determine death so that
we can increase the numbers of organs for donation."
For many doctors, harvesting organs only after brain death draws
a clear line in the sand, removing any conflict between patient
care and the interests of organ recipients. Often too, the decision
to withdraw life support is a subjective one. In the case of
Janet, a second specialist advised against ending life support,
and after almost a year in hospital, she is now wheelchair-bound
but happy to be alive. One concern is that if DCD becomes routine,
doctors caring for critically ill people may have their judgement
swayed by the needs of those on transplant waiting lists.
Michael Nicholson, a transplant surgeon at Leicester General
Hospital, a leading centre for DCD in the UK, thinks the potential
for conflict is overplayed. "Intensive care doctors have
to inevitably withdraw treatment from some people, irrespective
of whether the transplant team exists. When that happens the
least they can do is have the family talk with a transplant
coordinator," he says.
However, some critical-care doctors believe the problems go
even deeper. They argue cessation of heartbeat and breathing
are not necessarily irreversible, and point to cases where patients
whose hearts didn't respond to cardiac resuscitation later came
back to life - in one case a full 7 minutes later. By contrast,
this so-called "Lazarus phenomenon" has never been
documented in brain-dead patients.
Transplant surgeons who perform DCD point to a key safeguard
in their protocols - a waiting period between cessation of heartbeat
and allowing the transplant team to get to work. However, even
this may be being eroded by the need to retrieve organs before
they become too damaged. Originally, a 10-minute waiting period
was chosen because after this time the patient would likely
be brain-dead too. In many transplant centres this has now dropped
to 5 minutes, while three US transplant centres use a 2-minute
interval - before loss of brain function is total and when the
heart could start beating again, albeit only rarely.
The most controversial aspect of DCD is the practice of giving
patients drugs such as anticoagulants to preserve organs before,
or just as, life support is removed. This is banned in the UK
because it is deemed not to be in the interest of the patient,
but it is routine in many centres in the US, despite concerns
that it may hasten the death of the patient.
In Australia, where the ethics of DCD are still being considered,
"the consensus is that it's reasonable [to use drugs] but
only if it does not harm the donor and there has been prior
consent," says Peter Joseph, chair of AHEC's working party
on the ethics of organ donation. "We want the current consent
form changed so that you tick a box to specifically consent
to such interventions if you are on life support and your death
is imminent."
This is a step in the right direction, says Doig, but much more
needs to be done before DCDs become widespread. "Like any
other major healthcare issue, be it euthanasia or abortion,
what's important is that society debates the issue and comes
up with a position," he says. "Then, and only then,
individual practitioners can decide whether they want to partake."
From issue 2563 of New Scientist magazine, 04 August 2006, page
6-7
Redefining death
Using cessation of heartbeat as a sign of death before organ
removal was abandoned in most western countries in 1968 in favour
of "brain death", a more absolute sign that the lack
of consciousness is permanent.
By default that means that organs for transplant usually now
come from patients with severe head injuries who are brain dead,
but whose hearts and lungs have been kept functioning by machines,
keeping their organs in good condition.
One key reason for the switch from cardiac to brain death was
to assuage public fears that organs were being taken from people
who might otherwise have pulled through. It also got around
the problem of "dead" patients being kept alive by
life support, although this is unrelated to organ donation.
The criteria for brain-death include absence of brain-stem reflexes,
no evidence of breathing, and total lack of consciousness. Cardiac
death is defined by irreversible loss of heartbeat, breathing
and responsiveness. In the US, most states accept both definitions
of death, but in many countries there is no legal definition
of death.
Alternative sources of kidneys
The critical shortage of kidneys will worsen as numbers of patients
with renal failure caused by obesity-related diabetes and high
blood pressure soar. As a result, transplant centres are looking
at innovative ways of securing kidneys. These include:
Donation after cardiac death (see Main story).
Living donors, usually relatives or friends of the recipient.
The number of living kidney donors is set to overtake dead ones
in some countries.
Relaxing the criteria for donor kidneys to include kidneys that
are more likely to fail because the donor is older or has a
history of hypertension, for example. Patients waiting for a
transplant may get one sooner if they agree to take one of these.
En bloc kidneys: using two kidneys from a child in place of
an adult organ.
"Give and you shall receive": a proposal whereby if
you register as a donor, you would get priority should you ever
need an organ.
Organ procurement agents who closely monitor emergency departments
for potential donors, then approach their relatives for consent.
This has proved extremely successful in Spain.
