Following the advent of vascularized organ transplantation in the 1950s, improvements in the techniques of transplant surgery and in the management of patient immunosuppression have significantly increased the success of organ transplantation and the practicality of using transplantation to treat end-stage organ dysfunction. These successes have brought about an increased demand for donor organs.
The number of patients listed on transplant waiting lists has increased steadily; currently, more than 121,000 people are awaiting transplantation in the United States. [1, 2, 3, 4, 5, 6] Attempts to increase the donor supply have been insufficient to cope with this increased need. With this discrepancy, the number of patients who have died while awaiting transplantation has increased as additions to the waiting list far exceed donor availability and number of transplants performed, as demonstrated in the following image.
Significant attention has been devoted to the identification of other sources of organs for transplantation, but the mainstay of organ supply comes from deceased donor (cadaveric) donation. Nationwide, approximately 30% of all deceased organ donors come from trauma patients. The circumstances and mechanism of death in organ donors from 1999 to 2009 is shown in the images below. Evaluation of the trauma patient as a potential organ donor is critical to maximizing the availability of deceased donor organs for transplantation.
To maintain listings of potential organ recipients, the Department of Health and Human Services contracts the United Network for Organ Sharing (UNOS). Local organ procurement organizations (OPOs) are authorized by the Health Care Financing Administration and UNOS to manage the procurement of organs in their region. OPOs are responsible for organizing and overseeing the following:
Identification of donors
Evaluation of potential donors
Confirmation of diagnosis of brain death
Arranging consent from family
Clinical management of potential donor
Obtaining permission for visiting transplant surgeons to remove organs at the location of the donor
Preservation and packaging of organs for transplant
Organ allocation is decided by a complex set of guidelines that continuously evolve. UNOS maintains the lists of potential recipients divided by organ and ABO blood type. Potential recipients can be listed under multiple blood group lists as well as in multiple regions. Priority on each organ list is based upon several factors, including proximity to the donor, severity of illness, length of time on the waiting list, and special circumstances related to particular medical conditions. Objective scoring systems have been set up for the liver (MELD/PELD; see the MELD Score and PELD Score calculators) and the lung (LAS). These objective scoring systems are based upon defined physiologic and laboratory parameters. A point scale system determines the recipient's rank on each list. Organ allocation is then decided by the recipient'spoints and the following additional factors:
Location (local, regional, national)
Severity of illness (except kidneys)
ABO blood type compatibility
Length of time on waiting list
Histocompatibility leukocyte antigen (HLA) match (kidneys only)
Degree of preformed antigen sensitivity (panel reactive antibody score, kidneys only)
Other special factors (eg, pediatric patients in specific age categories, reciprocal sharing arrangements or pay back agreements, dual organ recipient, liver transplant for hepatic malignancy, acute failure of recent transplanted organ)
A study by Tsuang et al used a thoracic simulated allocation model and found that broader geographic sharing of pediatric donor lungs may increase pediatric candidate access to lung transplant. [7, 8]
Criteria for Organ Donors
Regional transplant centers have different sets of absolute and relative criteria for excluding potential organ donors. Early criteria were fairly strict, limiting evaluation to ideal donors aged 10-50 years with no comorbid conditions. With the increasing demand for organs, donation from an expanded donor pool has loosened restrictions considerably. Organs are harvested routinely from patients younger than 10 years and older than 50 years. Previously, such factors as hepatitis C or active bacterial infection were absolute contraindications. Now, such donors are often used for specific recipients. Relatively few absolute contraindications exist, and most potential donors are reviewed on a case-by-case basis. Additional absolute and relative contraindications are assessed for donation of specific organs.
Adaptations of the New England Organ Bank (NEOB) and the California Transplant Donor Network (CTDN) criteria are as follows:
- Age older than 80 years
- HIV infection
- Active metastatic cancer
- Prolonged hypotension or hypothermia
- Disseminated intravascular coagulation
- Sickle cell anemia or other hemoglobinopathy
- Malignancy other than in the central nervous system (CNS) or skin that is in remission (>5 y)
- Diabetes mellitus (DM)
- Physiologic age older than 70 years
- Hepatitis B or C
- History of smoking
Brain and Cardiac Death
Determination of brain death
No defined consensus exists on the most appropriate manner in which to determine brain death. The diagnosis is based principally on the clinical examination, but diagnostic tests often are used for confirmation. The success of organ procurement increases with a shorter interval from brain death to organ harvest; therefore, speed in diagnosis in the critically injured trauma patient is of some concern. To assist in raising the suspicion of clinical brain death for patients at risk for such, several clinical indicators augment a periodic neurologic examination, as follows:
Early indicators of brain death
- Hemodynamic lability
- Heart rate instability
- Decreased bronchial secretions
To complete the documentation of clinical brain death, the physician must demonstrate the following:
Correction of potentially reversible causes of coma
- Sedating medications
- Metabolic disturbances
- Endocrine disturbances
- Hypoxia or hypercarbia
Absence of brainstem reflexes (eg, cornea, pupillary light, oculovestibular, gag, oculocephalic)
Lack of respiratory effort (apnea test, ie, absence of respiratory movement after disconnection from respirator for sufficient duration to have pCO 2 rise to >50-60 mm Hg)
To confirm the diagnosis of clinical brain death, several additional diagnostic modalities may be employed. The confirmatory test can be repeated after an interval of 2-24 hours so that observer error can be avoided and persistence of the clinical state can be documented. Diagnostic tests include electroencephalogram (EEG), isotopic flow study, and transcranial Doppler.
Donation after cardiac death
Under some circumstances, the family of a trauma patient may wish to withdraw care from a critically injured patient who is unlikely to make a meaningful recovery. Although these patients may not meet criteria for brain death, the family may wish for donation. In these cases, procuring organs from the non–heart-beating donor is possible. Exact guideline protocols are established regionally or at individual institutions but involve the withdrawal of mechanical support followed by rapid organ procurement after the clinical pronouncement of death. The manner in which this occurs is of great ethical and practical debate.
Countries like the United States and Europe have been using donation after cardiac death (DCD) organs for many years. Canada, on the other hand, has only just begun to use DCD organs. Previously, the country had been almost exclusively using brain death organs for donation. In 2006, the Canadian Council for Organ Donation and Transplantation released DCD recommendations, and, by 2009, DCD donations had occurred in 30 Ontario hospitals. The establishment of a DCD program has led to a significant increase in deceased donation activity in Ontario. The province now has one of the highest organ donation rates in Canada. 
Donation after circulatory determination of death
Such donations can potentially increase the number of donor organs, but consent must occur before death. A multidisciplinary body consisting of representatives from the American Thoracic Society, the Society of Critical Care Medicine, the International Society for Heart and Lung Transplantation, the Association of Organ Procurement Organizations, and the United Network of Organ Sharing issued an ethics and policy statement that discussed such issues as the consent process, interventions, how death is determined, and end-of-life care. 
Consent for Organ Donation
The Uniform Anatomical Gift Act of 1968 requires explicit consent for organ donation. This act was revised in 1987 and then again in 2006 to better reflect current practices and encourage organ donation. [11, 12] In its current form, this act reaffirms that if a donor has gifted organs, their wishes should be honored and the family need not give additional consent. It also expanded the list of people able to consent for organ or tissue donation if a potential donor has not registered their wishes before death.
The Uniform Anatomical Gift Act requires that hospitals notify organ procurement organizations of patients who have died or are near death. In 2003 the Organ Donation Breakthrough Collaborative was formalized by the US Department of Health and Human Services in response to the organ shortage. The goal of this collaborative is to achieve donation rates of 75% or greater where possible.
Evaluation of the Potential Organ Donor
Evaluation of the potential donor continues after the determination of brain death with both general and organ-specific testing. The exact set of laboratory and diagnostic tests used varies from center to center, but an outline is presented, as follows:
- Basic laboratory values (eg, CBC, electrolytes, glucose, arterial blood gas [ABG])
- ABO blood typing
- HLA typing
- Blood cultures
- Sputum Gram stain, culture, and sensitivities
- Urinalysis, culture, and sensitivities
- HIV, Epstein-Barr virus (EBV), cytomegalovirus (CMV), human T-cell leukemia virus type 1 (HTLV-1), and hepatitis B and C virus serologies
- Venereal disease research laboratory (VDRL) test or rapid plasma reagent (RPR) test
- Inguinal lymph nodes tested for evaluation of recipient sensitivity
- Chest radiograph
- Cardiac catheterization (male >40 y or female >45 y, or younger if other cardiovascular risk factors present)
- Creatine kinase (CK), isoenzyme of CK with muscle and brain subunits (CK-MB), and troponin levels
- ABG on 100% FiO2; then, serial ABGs
- Chest radiograph
- Serial blood glucose determinations
- Amylase and lipase levels
- Liver function tests (LFTs)
- Liver biopsy - For patients with body mass index (BMI) of greater than 32, age older than 70 years (>60 y if DM), past medical history suggestive of liver disease, significant history of alcohol abuse, radiographic studies suggestive of fatty liver infiltration, or positive hepatitis serologies
- Prothrombin time (PT)
- Activated partial thromboplastin time (aPTT)
- Blood urea nitrogen (BUN)
- Creatinine (Cr)
Management of the Potential Organ Donor
Treatment of the trauma patient continues in the manner deemed optimal for the injuries sustained, until the determination of brain death. After this determination, treatment is directed at maintenance of organ function, while familial consent for organ donation is sought or until mechanical support is withdrawn.
The donor is managed with intensive care unit (ICU)–level care as the evaluation proceeds. Care is directed at preservation of the donor's hemodynamic state, protection of the donor organs, and avoidance or treatment of complications that are observed in the brain-dead donor. In addition to common problems observed in patients who are critically ill, many pathologic states are observed frequently in the patient who is brain dead. As the time from brain death to organ procurement increases, so does the number and severity of complications. Common complications present in these patients are noted in the image below.
In particular, donors who are brain dead are vulnerable to the effects of diabetes insipidus, cardiac arrhythmia, and endocrine dysfunction. Diabetes insipidus and its resultant sequelae (ie, hypovolemia, hypernatremia, hypokalemia, hyposmolarity) are managed with pitressin or desmopressin acetate (DDAVP). This treatment has been shown to delay asystole following brain death from 2 days to 3 weeks. Brain death is associated with disruption of the hypothalamic-pituitary axis. Donors can display adrenal insufficiency, lack of glycemic control, and hypothyroidism. Empiric steroids often are used, and management of other conditions follows clinical presentation.
Previously, ultrarapid progression from declaration of brain death to procurement was advised. Currently, there is a shift toward greater optimization of donor physiology prior to procurement. This also enables more precise coordination with recipient institutions and lessens cold-ischemia time.
Guidelines for donor management are prepared by each OPO. Specific areas of management concern, as adapted from NEOB and CTDN, are as follows:
- Lines - Central venous and radial artery lines, often pulmonary arterial catheters
- Vitals - Monitor blood pressure, pulse, central venous pressure (CVP), and pulse oximetry hourly or more frequently as needed.
- Temperature - Monitor every 2 hours and use cooling or warming blankets to maintain temperature at 97-100°F.
Blood pressure and vent management (rule of 100s)
- Maintain systolic blood pressure greater than 100 mm Hg with minimal inotropic support (eg, dopamine, neosynephrine, Levophed).
- Ensure the urine output is at least 100-300 cc/h.
- Ensure that pO2 is at least 100 mm Hg on the least amount of FiO2.
- Adjust intravenous (IV) fluid to maintain CVP of 4-12 mm Hg and urine output of 1-3 cc/kg/h.
- Treat diabetes insipidus (DI) - Suspect DI if urine output is greater than 3 cc/kg/h with urinary specific gravity of less than or equal to 1.005. Treat with DDAVP or vasopressin. Do not administer within 4 hours of procurement.
- Maintain CVP at 4-12 mm Hg, as tolerated by patient hemodynamics.
- Electrolytes - Correct electrolyte abnormalities as observed; elevated sodium is associated with adverse outcomes in liver transplantation.
- Steroids - Administer 15-30 mg/kg Solu-Medrol every 8-12 hours; this has been shown to increase the number of organs transplanted from each donor.
- Thyroxine (T3/T4) replacement - The role of thyroxine replacement in donor management is controversial; consider this in cases of refractory hypotension, arrhythmia, or cardiac dysfunction. Donor thyroid replacement has been shown to reduce 30-day mortality in heart transplant recipients. 
- Correct coagulopathy and transfuse blood to hematocrit (HCT) of 30 or greater.
- Administer empiric cefazolin or equivalent.
The organ procurement procedure requires careful coordination of several surgical teams. Commonly, teams are sent from each of the institutions of the designated recipients to the location of the donor. Separate teams for heart, lung, and abdominal organs participate. The harvest operation is conducted in defined steps to minimize the warm ischemic time of removed organs, and the organs are removed in the order of their susceptibility to warm ischemic damage. Because of the short time available for transplanting the preserved organs, particularly for heart and lungs, the preparation of the potential recipients and transplant teams also must be coordinated. The recipient operation often commences prior to the actual arrival of the organ at the recipient institution.
Prior to the operation, the donor must be adequately volume resuscitated and prepared for surgery. The management of intracerebral edema prior to brain death and resulting diabetes insipidus often results in a hypovolemic state that must be corrected prior to harvesting organs. The donor is volume resuscitated and brought to the operating room where appropriate positioning, monitoring, and ventilation are ensured prior to incision. Following this preparation, and when each team is in attendance, the procedure can begin. The outline of the surgical procedure is summarized below.
Steps in organ procurement
See the list below:
An incision from the suprasternal notch to the pubis is made; then, the chest is opened via median sternotomy, and the abdominal cavity is entered.
The thoracic and abdominal cavities are examined by respective teams for evidence of occult pathology and gross suitability of organs for transplant.
The small bowel is retracted, the right colon is mobilized, the posterior peritoneum is incised, and the duodenum and pancreas are reflected, allowing exposure of the inferior vena cava (IVC) and aorta.
Attachments of the heart, lung, liver, kidneys, and pancreas are incised; the organs are readied for removal.
The aortic arch, IVC, abdominal aorta, and portal vein or tributaries are cannulated for infusion of the preservative solution.
The aortic arch and supraceliac abdominal aorta are cross-clamped.
A cold preservative solution (typically University of Wisconsin solution) is infused through the inferior aortic, portal, and cardiac cannulae, with drainage of effluent via the IVC. The thoracic and abdominal cavities are packed with ice.
The organs are removed to the back table for initial preparation and packaging for transport.