CARE OF CADAVERIC ORGAN DONORS

Potential cadaveric donors are previously healthy or relatively healthy people who have experienced brain death and do not have an extracranial malignancy or untreatable infection. Less than 5% of deaths satisfy these criteria, and only 10% to 20% of these eligible subjects actually become organ donors. In addition, a significant proportion of potential organ donors are lost to either medical failure or an inability to obtain consent for donation.^{[10] [11]} Significant ethical conflicts surrounding the definition of brain death in different social and cultural constructs had been an obstacle in transplantation.^{[12] [13] [14]} In the United States and Western Europe, a consensus has been achieved among the scientific community with regard to the definition of brain death. However, there is and will continue to be considerable discussion about concepts and definitions of death and the legal definition of death.^[15] Furthermore, these issues are colored by the effects of cultural differences; concepts and definitions of death are not easily transferred from one culture to another. Many Western cultures have committed to cadaveric organ donation, and the emphasis of discussion is quite different from that in Japan or Taiwan, for example.

Determination and Declaration of Brain Death (also see Chapter 79 )

Worldwide, there is uniform agreement on the neurologic examination of adult brain-dead subjects, with the

TABLE 56-1 -- Brainstem reflexes that should be absent in brain death

Pupillary response to light

Corneal reflex

Oculocephalic reflex (doll's eye response)

Oculovestibular reflex (caloric response)

Gag and cough reflex

Facial motor response

exception of the apnea test. However, standardization of the procedures for diagnosing brain death is quite different among countries.^[16] Criteria promulgated by the American Academy of Neurology in 1995 are generally applied in North, Central, and South America.^{[16] [17]} These criteria grew out of the landmark Harvard criteria published in 1968.^[17] In Europe, criteria for the clinical evaluation of brain death are also fairly uniform, with the principal difference being the number of physicians needed to confirm the diagnosis. Several criteria have to be fulfilled to declare brain death. At the time of examination, the patient must be comatose with neither spontaneous movement nor response to painful stimuli. A lack of brainstem activity should be confirmed by assessment of the brainstem and the apnea test ( Table 56-1 ). Possible causes of reversible cerebral dysfunction should be excluded (e.g., hypothermia, residual drug effects). For the apnea test, the patient is preoxygenated with 100% oxygen for 10 minutes, PCO₂ is confirmed to be in the normal range (35 to 45 mm Hg), and the patient is administered 100% oxygen for 10 minutes. Subsequently, the patient is disconnected from the ventilator, and blow-by oxygen is administered with a T-piece. After 7 to 10 minutes, blood is drawn for arterial blood gas measurement. A PCO₂ value greater than 60 mm Hg confirms lack of brainstem control of ventilation and represents a positive apnea test. No signs of spontaneous respiratory effort should be observed during this procedure. Confirmatory tests such as transcranial Doppler, electroencephalography, and auditory evoked potentials may also be used.