Chapter 13: Transplant Surgery

Brain death (core), Organ donation (advanced)

May present after stroke, TBI, anoxic brain injury, etc

All patients with severe brain injuries who are brain dead or likely to progress to brain death should be considered potential organ donors → referral to local organ procurement organization

Brain death = irreversible, catastrophic brain injury causing total cessation of brain function

Criteria for brain death declaration:

• - Irreversible, unresponsive coma with known cause

• - Exclude potentially reversible medical conditions (ie, acid-base or electrolyte derangements, endocrine function, paralytic or CNS depressant meds, hypothermia, etc)

• - Brain death exam

  • Fixed and dilated pupils

  • Absence of brainstem reflexes—corneal, oculocephalic, oculovestibular, gag, cough

    • Spinal reflexes are NOT a sign of brain activity

  • No motor response to noxious stimuli

  • No spontaneous respirations

  • Some states require two brain death exams by different physicians with defined time interval between the two

• - Confirmatory apnea test—the most definitive finding supporting the diagnosis of brain death

  • PaCO₂ normalized to 40 mm Hg, patient preoxygenated with 100% FiO₂ and then disconnected from ventilator and placed on 100% FiO₂ delivered passively to ETT via T-piece

  • ABG drawn after ~10 min

  • If there is no evidence of spontaneous respiratory activity, PaCO₂ ≥ 60 mm Hg, and pH is acidotic, this is considered evidence of brain death

  • If there is any evidence of respiratory activity, patient is not brain dead, return to vent immediately

  • Apnea test not valid for patients with cervical fracture above C4 or on substances that depress respiratory drive

• - Adjuncts: Cerebral angiography (gold standard), cranial doppler, CTA, MRA, and nuclear cerebral blood flow scan

  • Can be obtained to evaluate for brain death if brain death exam and/or apnea test cannot be performed

Donation after cardiac death—a way for patients with severe brain injury who do not technically meet the criteria for brain death to be donors

Must have family consent before patient can be an organ donor

Patients with severe brain injury develop physiologic derangements that must be treated to prevent cardiovascular collapse and loss of useable organs

• - Autonomic dysregulation → profound vasodilation and hypotension

  • Increased ICP initially causes catecholamine storm, but patient eventually loses sympathetic tone causing peripheral vasodilation and hypotension

• - Depletion of ADH → diabetes insipidus → inappropriate diuresis, hypovolemia, hyperosmolality, and hypernatremia

Without intervention, brain death is usually followed by severe injury to all organs and circulatory collapse within 48 h

Renal transplant (advanced)

Patient may have ESRD due to a variety of different ...