Critical Care of Organ Transplant Recipients: Overview
Christoph Troppmann
I. GENERAL PRINCIPLES
A. The increased number of organ transplants (28,051 transplants in the United States in 2012, compared with 12,623 in 1988) has been paralleled by significant improvements in both patient and graft survival. These improvements can be attributed to several factors.
1. The availability of polyclonal and monoclonal antibody preparations (antithymocyte globulin, anti-CD 52-directed alemtuzumab, and anti-IL-2 receptor-directed basiliximab) to prevent and treat rejection episodes.
2. The introduction in the 1980s of a powerful immunosuppressant agent, cyclosporine, followed a decade later by tacrolimus and mycophenolate mofetil. More recently, additional new drugs have become available (e.g., sirolimus, everolimus, belatacept), augmenting the immunosuppressive armamentarium considerably and allowing for more individualized immunosuppression of organ recipients.
3. Improvements in organ preservation (e.g., introduction of the University of Wisconsin preservation solution in the late 1980s).
4. Thorough preoperative patient screening.
5. Increasing sophistication in postoperative intensive care, allowing also for transplantation in high-risk recipients with significant medical comorbidities.
6. Availability of potent, yet nontoxic antibacterial, antifungal, and antiviral agents has allowed for more effective prevention and treatment of opportunistic infections.
7. Refinements in surgical techniques.
B. Transplantation has therefore become the treatment of choice for many patients with end-stage failure of kidneys, liver, endocrine pancreas, heart, lungs, and small bowel. Criteria for potential recipients have been expanded to include infants, children, and individuals thought to be at higher risk for complications (e.g., patients with diabetes, elderly patients).
C. Current absolute contraindications to transplantation include malignancy (untreated, metastatic, or at high risk for recurrence); uncontrolled infection; and medical-surgical contraindications to undergo, or inability to recover from, a major surgery.
D. The gap between available organs and patients awaiting transplantation is widening. As a result, mortality on many transplant wait lists is increasing.
II. THE ORGAN DONOR SHORTAGE: POTENTIAL SOLUTIONS
A. Live donors.
1. Owing to the lack of deceased organ donors, and the development of a noninvasive (laparoscopic) nephrectomy technique, the number of live donor kidney transplantation has significantly increased. In 2001, for the first time, live kidney donors outnumbered deceased kidney donors in the United States. Current initiatives (e.g., wider implementation of paired kidney exchange for incompatible live donor-recipient pairs) aim at increasing live donor transplant rates even further.
2. Live donor liver, small bowel, and lung transplants are also performed but continue to represent only a very small proportion (<4%) of each of those transplants.
B. Deceased organ donors.
1. The overall number of deceased organ donors in the United States has increased by 36% over the past decade (5,985 donors in 2000 vs. 8,143 donors in 2012).
2. Brain dead donors: still by far the most common deceased donor type (88.3% of all deceased donors in the United States in 2011).
3. Donation after cardiac death (DCD) donors: an increasingly used donor type. In a typical scenario, families of unconscious patients who do not fulfill the formal criteria of brain death (e.g., patients with severe, irreversible terminal brain injury or neurological disorders), decide to forego any further treatment and then decide to donate the organs. In 2011, DCD donors represented 11.7% of all deceased organ donors in the United States.
