WHAT SORT OF CONDITIONS NEED LUNG TRANSPLANT?
Patients with a variety of diagnoses may be treated
with a transplant when the lung disease is in its most extreme form and
their very survival is threatened. Many of them have chronic infection
of the lungs from either cystic fibrosis or other conditions such as
bronchiectasis. Some may have destruction of the lungs from emphysema
which in some patients is as a result of smoking. In some older
patients pulmonary fibrosis, scarring of the lung from an unknown cause
may be the reason they need a transplant. Patients with lung cancer
are not suitable for transplant: the cancer would rapidly return in the
situation of immunosuppression after a transplant.
HOW AM I REFERRED FOR A TRANSPLANT?
Patients with lung disease are looked after by chest
physicians at hospitals all around the UK. Those with cystic fibrosis
are managed in specialised centres. All of these hospitals will have
links to their local lung transplant centre and will make a referral if
it is felt that you are suitable for a lung transplant. Patients are
admitted for a period of assessment. The multidisciplinary team,
consisting of chest physicians, surgeons, physiotherapists, social
workers and co-ordinators together with specialist nurses will decide
if there is any alternative for transplant and whether you are
otherwise for transplant. If accepted you will be placed on the
waiting list: the average wait is currently about a year. Because of
the relative shortage of lungs currently 20-30% of patients will not
survive to receive their new one.
WHAT HAPPENS IN A LUNG TRANSPLANT?
Lungs suitable for transplant, organ donor, are
allocated to recipients on the basis of size and blood group. In each
centre a decision will be made about the sickests patients and they
receive priority for a transplant. There is no national system to give
lungs to the most urgent patients. A detailed assessment is made of
the lungs in the donor and if suitable they are removed and flushed
with cold preservation solution. They should be transplanted into the
recipient within 8 hours so are taken directly back to the lung
transplant centre. In the meanwhile the recipient will be
anaesthetised, and once the lungs are known to be satisfactory, the
chest is opened. The old lung or lungs are removed and the new lungs
sewn into place. Removal of the old lungs, particularly if there is a
lot of scarring related to infection, is one of the most difficult
parts of the operation. Immunosuppression is started immediately after
the transplant and the lungs are carefully monitored for any evidence
of rejection. It is relatively common and requires prompt treatment.
Both of the lungs need relatively high amounts of immunosuppression,
and because they are exposed to the outside air, infection is
relatively common and this again needs to be treated aggressively.
WHAT ARE THE RISKS OF LUNG TRANSPLANTATION?
The surgery itself can be long and difficult
particularly for the bilateral lung transplant operation. However the
commonest cause of early death is failure of the new lungs to work
properly. This is unpredictable but happens in about 10% of patients
and is the cause of death in about 5%. In general, about 90% of
patients survive the transplant and most of those will go on to still
be alive a year later.
The body does tend to attack the new lungs through
the immune system and in a number of other ways that are only just
being understood. For this reason the new lungs often fail after a few
years. However the success rate is not such that more than 50% of
patients will survive 10 years and a number will reach 20 years after a
transplant.
All the results from the centres in the United
Kingdom are monitored by the
Thoracic Transplant Audit, which is run by
the Royal College of Surgeons.
An annual report
is sent to the National Commissioning Group (NCG). In addition the UK
provides figures for the International Society for Heart and Lung
Transplantation. This publishes an international registry. Much
interesting information is available on the
ISHLT website
NEW DEVELOPMENTS IN LUNG TRANSPLANTATION
With the consent shortage of donor lungs for
transplantation, a number of research avenues have been explored. Two
of these are potentially very exciting.
Lung transplant after non heart beating donation:
Removal of organs from the donor after the circulation has stopped has
made a lot of progress in kidney transplantation. However the lung may
be the most suitable for transplantation from this sort of donor. In
contrast with other solid organs such as the liver or the kidney, the
lung can be kept alive by simple inflation. Oxygen contained within
the lungs air sacs enables the metabolism to continue and therefore the
tissues can remain intact. The inflated lung remains alive and
suitable for transplant for up to an hour after the circulation has
stopped. The UK has been a leader in this field. At one centre in
2008, lungs from non heart beating donors increased activity by 15%.
Ex vivo lung perfusion: A lot of damage may occur
to the lung while it is still in the organ donor. Some of this damage
is caused by the processes involved in brain stem death. Because of
this damage only about 15% or 20% of potential donor lungs can be used
for transplant. A new technique has been pioneered in Sweden and in
Canada. After removal from the donor and transport back to the
transplant centre, the lung is placed on a special perfusion rig
whereby blood and a special solution is pumped through the arteries of
the lung whilst it is gradually rewarmed. This process has the
function of “reconditioning”, reversing much of the pre-existing
injury. This technique has been used no more than 20 times around the
world but all of the patients have done well. It would seem that the
number of lungs that can be used from donors might go from 20% to even
30% or 40%. Two centres in the UK have preliminary experience with
this technique which is perhaps the most exciting development in the
field for 20 years.
