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840 PART 6: Neurologic Disorders

donors we prefer use of colloids to reduce the risk of precipitat- Hypophosphatemia is frequently observed in brain-dead patients,
ing acute heart failure, especially in patients with brain injury– and if untreated, may lead to hemolysis, rhabdomyolysis, and platelet
related myocardial abnormalities. Inotropic support is indicated dysfunction. Glucose, potassium, and ketones should also be checked
for a volume-resuscitated patient with systolic blood pressures regularly, as hyperglycemia due to relative insulin resistance, and use of
<100 mm Hg; principally, any vasopressor agent can be used; how- steroids and glucose-containing solutions is frequent in these patients.
ever, ideally use the lowest dose possible to avoid further organ Often an insulin infusion is required to maintain blood glucose levels
impairments. Consumption of blood factors and platelets due to between 150 and 200 mg/dL.
disseminated intravascular coagulation (aggravated by massive
release of brain thromboplastin) can be rapid and replacement may The proper diagnosis and management of brain death is complex and
become increasingly difficult. requires expertise and respect for the diagnosis as a real mechanism of
death. The need for proper diagnosis supersedes whether or not the
The use of a lung protective ventilatory strategy is recommended dur- patient will become an organ donor. However, the sensitive and thought-
ing the support of potential lung organ donors. Such a strategy utilizes ful management of the patient and family can at least keep the option of
a small tidal volume (6-8 mL/kg of predicted body weight), a relatively organ donation open, a decision to be finalized between organ procure-
high PEEP level (eg, 8-10 cm H O), apnea testing performed by using ment agencies and usually families. This is one situation in which proper
2
continuous positive airway pressure, and closed circuit for airway suc- management can potentially save several lives.
tioning. It has been associated with increased number of eligible and
harvested lungs compared with a conventional strategy of lower tidal
volumes, lower PEEP levels, and opening of the airway circuitry. 72
2. Manage diabetes insipidus: Posterior lobe pituitary injury and KEY REFERENCES
necrosis leading to diabetes insipidus (DI) in brain-injured and
brain-dead patients is common and should be recognized imme- • Fisher CM. The neurological examination of the comatose patient.
diately. Helpful clinical parameters supporting the diagnosis of DI Acta Neurol Scand. 1969;45(suppl 36):31-56.
include (1) hypotonic polyuria, identified by urine output >4 mL/kg • Giacino JT, Ashwal S, Childs N, et al. The minimally conscious
per hour and urine specific gravity <1.005; (2) urine osmolality state: definition and diagnostic criteria. Neurology. February 12,
<300 mOsm/L; and (3) plasma osmolality >300 mOsm/L (may be 2002;58(3):349-353.
confounded by the use of osmotic diuretics). Diabetes insipidus will • Medical aspects of the persistent vegetative state (1). The
invariably lead to dehydration, hypernatremia, and vascular collapse. Multi-Society Task Force on PVS. N Engl J Med. May 26,
Therapy is simplified by early recognition of DI and includes 1994;330(21):1499-1508.
hypotonic fluid resuscitation on a volume-to-volume basis, and
desmopressin acetate, for example, as an initial bolus of 0.3 µg IV, • Medical aspects of the persistent vegetative state (2). The Multi-Society
Task Force on PVS. N Engl J Med. June 2, 1994;330(22):1572-1579.
and then as an adjusted dose guided by clinical and laboratory
parameters (eg, titrate urine output to 2-3 mL/kg), given approxi- • Monti MM, Vanhaudenhuyse A, Coleman MR, et al. Willful
mately every 6 hours to a total 24-hour dose ranging from 1 to 4 µg. modulation of brain activity in disorders of consciousness. N Engl
Infusion of aqueous vasopressin can be used alternatively (start at J Med. February 18, 2010;362(7):579-589.
1-3 U/h); however, the infusion should be stopped prior to surgical • Oddo M, Carrera E, Claassen J, Mayer SA, Hirsch LJ. Continuous
organ recovery to diminish the dose-dependent effects on systemic electroencephalography in the medical intensive care unit. Crit
vascular constriction. Recently, the addition of thyroid hormone Care Med. June 2009;37(6):2051-2056.
replacement was shown to have a vasopressor-supporting effect. • Petty GW, Mohr JP, Pedley TA, et al. The role of transcra-
73
The management of diabetes insipidus can be complex, and is best nial Doppler in confirming brain death: sensitivity, specificity,
guided by those experienced with brain death management. and suggestions for performance and interpretation. Neurology.
3. Maintaining normothermia: Adverse effects of hypothermia are February 1990;40(2):300-303.
well known and include reduction of cardiac output and peripheral • Posner JB, Saper CB, Schiff ND, Plum F. Plum and Posner’s
vascular resistance leading to arrhythmia and hypotension, hypoxia, Diagnosis of Stupor and Coma. 4th ed. USA: Oxford University
hyperglycemia, and coagulopathy. Brain-dead patients have lost Press; 2007.
their ability to control body temperature and are hence dependent
on ambient temperature and the temperature of the infusion prod- • Wijdicks EFM. Brain Death: A Clinical Guide. Baltimore, MD:
ucts they receive. For these reasons (as well as for the establishment Lippincott Williams & Wilkins; 2001.
of the diagnosis of brain death), the core temperature should be kept • Wijdicks EFM, Varelas PN, Gronseth GN, Greer DM. Evidence-
constantly above 36°C using conventional methods. based guideline update: determining brain death in adults.
4. Maintain glucose and electrolyte balance: Hypernatremia (eg, from Neurology. 2010;74:1911-1918.
untreated DI) in excess of 155 mEq/dL may lead to a higher inci-
dence of graft loss after liver transplantation and should therefore be
treated aggressively. Certainly, electrolytes need to be evaluated and
74
supplemented as needed, at least every 2 to 4 hours, especially with REFERENCES
aggressive fluid resuscitation and treatment of DI, as hypernatremia,
hypokalemia, hypocalcemia, and hypomagnesemia are common. Complete references available online at www.mhprofessional.com/hall

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