LUNG TRANSPLANTATION (also see
Chapter 49
)
Since its first successful application in 1983, lung transplantation
has emerged as a relevant, effective therapy for end-stage lung disease. The combination
of modern immunosuppressive therapy and continuing advances in surgical, anesthetic,
and intensive care management has led to its current status as a realistic option
for many patients with crippling or life-threatening pulmonary conditions. Both
increased survival and dramatic improvement in quality of life are routinely achieved
by those who undergo this procedure.[285]
[366]
[367]
[368]
[369]
Nonetheless, lung transplantation continues to lag behind most other solid organ
transplantation procedures in terms of both early and late patient survival ( Table
56-5
), as well as organ availability. Perioperative complications such
as infection and primary graft failure are largely responsible for an early (30 day)
mortality rate of about 10%.[285]
[366]
[367]
[370]
The
principal obstacles to long-term survival are posed by infection and especially by
bronchiolitis obliterans, the pulmonary expression of chronic rejection.[285]
Organ Matching and Allocation
Lung transplantation for adults, as currently practiced, generally
refers to one of three different operations: heart-lung transplantation (HLT), single-lung
transplantation (SLT),
*Survival
contingent on being alive 1 year after transplantation.
†Time
at which 50% of patients are still living.
and bilateral sequential lung transplantation (BSLT). (For practical purposes, these
terms universally connote whole-lung organs from cadaveric sources, although individual
lobes may be retrieved from living donors, usually parents or other relatives of
the recipient, for cases of bilateral lobar transplantation.[371]
)
Patients with primary lung pathology typically undergo isolated lung transplantation
(i.e., SLT or BSLT), even in cases of associated secondary RV enlargement or dysfunction.
If significant comorbid LV dysfunction is present, as may be caused by CAD, patients
may instead undergo HLT. Even though patients with Eisenmenger's syndrome would
historically have undergone HLT, it is now recognized that many patients may benefit
from isolated lung transplantation provided that the cardiac defect can be surgically
repaired.[372]
In this way, the patient is not
exposed to the risk of transplant-associated CAD (see discussion in the section "Anesthesia
for Patients after Heart Transplantation"), and the use of scarce donor organs is
maximized. Nonetheless, patients with Eisenmenger's syndrome, including those with
potentially correctable cardiac defects, currently account for most patients who
undergo the relatively uncommon HLT procedure. Other typical indications include
primary pulmonary hypertension (PPH) and CF, each accounting for roughly 20% of HLT
operations performed annually.[285]
[372]
Candidates for BSLT and SLT procedures are selected on the basis
of pulmonary disease sufficiently advanced that survival beyond 2 years is unlikely
despite optimal medical management. In patients who present for isolated lung transplantation,
the most frequent underlying conditions are chronic obstructive pulmonary disease
(COPD), idiopathic pulmonary fibrosis (IPF), CF, α1
-antitrypsin
deficiency, and PPH. A variety of less common pulmonary diagnoses, including sarcoidosis
and retransplantation, as well as congenital heart diseases (i.e., those with Eisenmenger's
syndrome), are found less frequently.[285]
Certain guidelines are generally followed, with occasional exceptions,
in the selection of suitable lung transplant recipients ( Table
56-6
). In this way, the probability is optimized that transplantation
will enhance, not limit patient survival while at the same time ensure that donor
organs are used with the greatest possible benefit.
In some situations, including previous malignancy,[368]
current ventilator dependence, high-dose corticosteroid use,[373]
previous thoracic procedures (especially those involving pleurodesis or patients
with extensive
TABLE 56-6 -- Recipient selection criteria for lung transplantation
|
Recipient Selection Guidelines |
Recipient Selection Contraindications |
|
Clinically and physiologically severe disease |
Acutely ill or unstable clinical status |
|
Medical therapy ineffective or unavailable |
Uncontrolled or untreatable pulmonary or extrapulmonary infection |
|
Limited life expectancy, usually less than 2 to 3 yr |
Uncured neoplasm |
|
Ambulatory with rehabilitation potential |
Significant dysfunction of other vital organs, especially the
liver, kidney, and central nervous system |
|
Acceptable nutritional status, usually 80% to 120% of ideal body
weight |
Significant coronary disease or left ventricular dysfunction |
|
Satisfactory psychosocial profile and support system |
Active cigarette smoking |
|
Adequate coverage for the procedure and for post-transplantation
care |
Drug or alcohol dependency |
|
Age younger than 65 yr |
Unresolvable psychosocial problems or noncompliance with medical
management |
adhesion formation), and colonization with certain multidrug-resistant bacteria (mostly
a problem in CF or bronchiectasis patients), it is difficult to determine whether
a patient is a valid candidate for transplantation. The degree of contraindication
posed by each of these factors varies between transplantation centers.
Once the patient is found to be a candidate, the decision of which
specific transplantation procedure to perform (SLT, BSLT, or HLT) is frequently made
on the basis of institutional or surgeon preference. The decision is guided by the
underlying pulmonary and cardiac pathology, the degree of coexisting pulmonary hypertension,
and the presence and nature of any comorbid conditions harbored by the recipient.
These preferences are continually revised as worldwide experience evolves, and the
available data may lead to contrasting practice patterns at different transplant
centers. Certain generalizations can be made, however. Lung pathology with significant
bacterial colonization as exemplified by CF and generalized bronchiectasis is usually
managed with bilateral lung transplantation to prevent cross-contamination between
the native lung and its adjacent allograft.[367]
[368]
[374]
Children
or young adults with CF are the most common recipients of the relatively uncommon
living related bilateral lobar lung transplantation procedure. Patients with COPD
(including the subset with α1
-antitrypsin deficiency) may undergo
either bilateral or single-lung transplantation, usually the latter, yet recent data
suggest a possible survival benefit with BSLT.[285]
Unilateral transplantation is generally favored in patients with IPF because the
retained native lung's decreased compliance and increased PVR favor the distribution
of both ventilation (V̇) and flow (
) toward the allograft.[368]
PPH patients would be expected to have significant V̇/ mismatching after
SLT procedures because of high PVR and normal compliance in the native lung. The
lack of evidence makes it unclear whether SLT or BSLT affords better survival. HLT,
which had been the standard of care for PPH patients, is currently performed less
often[368]
; severe RV dysfunction resulting from
pulmonary hypertension is now recognized to improve after lung transplantation[374]
and thus less frequently prompts HLT as opposed to isolated lung transplantation
techniques.
 |
