Organ Donation
Kristen L. Nelson Mcmillan
Thomas A. Nakagawa
Ivor D. Berkowitz
KEY POINTS
Options for organ donation include donation after brain death (DBD), donation after cardiac or circulatory death (DCD), and living donation.
The demand for organs currently far exceeds the available supply for several reasons. Approximately 50% of family members currently refuse to give consent for organ donation from their deceased loved ones. Other reasons include the failure to identify eligible donors and failure to give families the option of donation.
Request for organ donation should be a collaborative process between the ICU team and the organ procurement organization (OPO) ensuring the family is approached in a professional and compassionate manner to inform the family of the death of their loved one and request donation.
The option of donation should be preserved for all patients.
In cases of DCD, the decision to withdraw life-sustaining medical therapies must always have been made prior to discussing organ donation.
Relatively few absolute contraindications exist to rule out organ donation, and often these absolutes become relative based on the individual recipient.
Many OPOs and ICUs utilize standardized donor management protocols.
Donor management of the brain-dead patient requires a change in goals of care from cerebral-protective strategies to organ-donor-supportive strategies.
Several hemodynamic changes occur in brain-dead patients that may ultimately affect the potential transplantability of organs.
Brainstem ischemia results in uncontrolled sympathetic stimulation commonly referred to as “catecholamine storm,” which ultimately results in catecholamine depletion and hemodynamic collapse from myocardial dysfunction and poor vascular tone. As many as 25% of potential donors are lost due to this hemodynamic instability.
Hypotension is the most common problem encountered by physicians who care for pediatric organ donors; it can be caused by vasodilation, hypovolemia (due to diuretic use, diabetes insipidus [DI], osmotic diuresis, and hypothermia), and myocardial dysfunction.
Optimal central venous pressure (CVP) for managing brain-dead organ donors is often between 8 and 10 mm Hg.
Myocardial dysfunction is multifactorial and may be due to altered loading conditions, ischemia, acidosis, hypoxia, and massive cytokine release, which results in a systemic inflammatory state and abnormal function of the hypothalamic-pituitary axis resulting in pituitary hormone depletion.
Dopamine has been the vasopressor most commonly used in pediatric organ donors, because renal and splanchnic blood flow can often be maintained at levels <10 µg/kg min.
The vasoconstriction associated with α-adrenergic agents, such as phenylephrine, epinephrine, and norepinephrine, must be taken into account, because perfusion to organs may be compromised, particularly the kidneys, liver, and heart.
Vasopressin acts synergistically with catecholamines and may result in a much-reduced requirement for catecholamines.
Intractable hypotension should raise the suspicion of hormone deficiency, and replacement with thyroid hormone and corticosteroids should be strongly considered.
Currently, most transplant centers and OPOs routinely administer T3 or T4, in addition to methylprednisolone, vasopressin, and, often, insulin to brain-dead donors to improve or prevent the deterioration in myocardial function and restore normal physiologic parameters.
