Support in Solid-Organ Transplantation
Darrell J. Triulzi, M.D.
transplantation continues to grow as a treatment modality. Currently
more than 74,000 patients are waiting for an organ transplant. However
in 1999 only 21,990 transplants were performed, limited primarily by the
availability of organs. Transfusion support remains an integral part of
solid-organ transplantation, imparting demands on the transfusion
service not only quantitatively in terms of blood product support, but
also due to the unique requirements for specialized blood components,
the complex serologic problems, and the immunologic effects of
transfusion on both the allograft and the recipient.
BLOOD COMPONENT UTILIZATION
typical requirements for blood components for each type of organ
transplant in adults are shown in Table 1.
Liver transplant procedures require the most blood components
despite the fact that blood use in liver transplantation has declined
dramatically over the last decade.
The multiple factors contributing to the reduction in blood usage
include: improved surgical technique, organ preservation, and anesthetic
management, as well as better intraoperative monitoring of coagulation
status and pharmacologic treatment of fibrinolysis. Heart
transplantation is associated with lower blood requirements that
approximate blood usage observed in complex cardiopulmonary bypass
procedures. Blood usage in
lung transplantation varies by the type of lung transplant procedure.
More than 2/3 of single-lung transplant recipients do not require any
transplant procedures typically require more red cells than heart
transplant procedures. The
majority of patients receiving kidney transplants do not require blood.
STRATEGIES FOR SELECTION OF COMPATIBLE COMPONENTS
solid-organ transplant procedures other than liver, transfusion
requirements are generally not sufficient to require deviation from
traditional selection criteria of ABO identical/compatible red cells.
However, in liver transplantation, transfusions frequently exceed
the available supply of ABO identical red cells, antigen-negative red
cells, or compatible plasma, and thus require blood bank blood group
switching protocols to optimally use available blood resources.
with Clinically Significant Alloantibodies
potentially clinically significant red cell alloantibodies are found in
approx 6% of liver transplant candidates.
Usually at least 8-10 units of antigen compatible blood can be
found for surgery. In order to minimize the risk of hemolysis, these patients
are ideally managed by using antigen-negative units for the first 5-10
units, switching to antigen-unscreened units in the middle of the case,
and then switching back to antigen-negative units for the last 5-10 U
transfused. This strategy
requires close communication between the anesthesiologist and blood
COMPONENTS (Table 2)
infection is the most frequent infectious complication following solid
organ transplantation. In
seropositive solid organ recipients, reactivation of latent virus
represents the major risk for CMV infection. Thus, there is no
documented benefit to providing blood CMV neg/safe components to
patients who are CMV seropositive.
In seronegative patients, the major source for primary CMV
infection is the seropositive transplanted organ and, to a lesser
extent, transfused blood components. Published data indicate that
although the overall rate of CMV transmission by transfusion is low
(5-15%), the morbidity associated with this complication would support
the use of methods to prevent CMV transmission from blood components.
Historically, this was accomplished by using blood components
from donors who lack antibodies to CMV. Published data suggest that
leukocyte reduction by filtration is equally effective in reducing the
risk of CMV transmission from blood.1 It appears that this
method would also be effective in solid-organ transplant recipients.2
Irradiated Blood Components
Graft vs host disease (GVHD) is a rare complication of organ
transplantation (59 cases) reported most frequently in liver recipients
and is almost always due to the donor organ. Transfusion associated GVHD
is very rare in solid organ transplant recipients with only 4 published
cases. Only two of these had convincing supportive evidence, and one of
these had an under-lying hematologic abnormality.
These few cases do not support a policy of routine irradiation of
cellular blood components for organ transplant recipients.
to HLA antigens is of considerable importance in organ transplantation. A sensitized patient presents problems in identifying a
crossmatch-compatible donor and, for some organs, the outcome of
transplantation is inferior. However,
white cells in blood components may be beneficial in inducing tolerance
and prolonging allograft survival.
Thus, the decision to provide leukocyte-reduced components must
weigh the risks and benefits of these opposing effects.
HLA alloimmunization has clearly been shown to be associated with
decreased graft survival in renal transplantation and more recently in
heart and/or lung transplantation.
However, liver allograft survival is not adversely impacted by
HLA alloimmunization. Thus, leukoreduction to prevent alloimmunization
provides benefit to kidney, heart, and lung recipients.
The beneficial immunomodulatory effect of non-leukoreduced
transfusions on allograft survival has only been demonstrated for renal
transplant recipients. This effect is only apparent when the blood donor
shares an HLA haplotype with the recipient.
The magnitude of the effect has become less apparent with
currently available immuno-suppressive drugs, and thus transfusions are
not routinely used for this indication.
BLOOD GROUP SYSTEM IN ORGAN TRANSPLANTATION
ABO system is clinically important in two aspects of solid-organ
transplantation: first, as a transplantation antigen that influences
graft survival, and second as an antigen-antibody system implicated in
immune hemolytic anemias in ABO non-identical organ transplant
System as a Transplantation Antigen
across ABO lines will typically cause hyperacute rejection of kidney and
heart transplants, although exceptions do exist.
Successful transplantation of kidneys and hearts across ABO lines
has been accomplished by removing ABO antibodies in the recipient or by
taking advantage of the variable expression of ABO antigens such as in
A2 individuals or neonates. In
general, ABO-incompatible organs are avoided in kidney and heart
transplantation. ABO major mismatch liver allografts are used in 6.9% of
pediatric and 2.4% of adult liver recipients due to organ shortages.
Liver allografts are felt to be resistant to hyperacute rejection
when transplanted across ABO barriers although reports of hyperacute
rejection do exist. ABO-incompatible
liver transplants are commonly associated with acute graft failure with
a 46% graft failure rate reported within 30 days of the transplant.
Plasmapheresis to remove recipient isohemagglutinins and/or
splenectomy may be of benefit. Currently,
ABO-incompatible liver allografts are reserved for patients with
fulminant liver failure in whom death is imminent without
transplantation and when an ABO-compatible organ is not available.
ABO compatible but non-identical (minor mismatch) liver
transplants are associated with modest reductions in 1- and 3-yr
lymphocytes transplanted with the donor organ are capable of producing
ABO antibodies and hemolysis in ABO mismatched organ recipients. A
positive Coombs test +/- hemolysis is typically observed 7-10 days after
transplantation. Blood Bank protocols for optimal component selection
are required to minimize hemolysis.
Bowden RA, et al. Blood 1995; 86:3598-3603.
Lopez-plaza I, et al. Transfusion 1999;39:S385.
DJ et al. Transfusion 2001;41:419-26.
Blood Use (Units) in Organ Transplantation
for use of specialized blood components in CMV seronegative
solid-organ transplant recipients
*CMV-negative pairs only.
Components rendered CMV-safe by filtration are a
Copyright © 2001, The Institute For Transfusion Medicine