BRAIN DEATH IN NEONATES Behnaz Basiri Neonatologist Associated Professor- Hamadan University of Medical Science

Brain death (BD) is the defined as the final cessation of activity of the central nervous system, especially as indicated by a flat electroencephalogram (EEG) for a predetermined length of time. Brain death (BD) is the defined as permanent and irreversible loss of brainstem and cortical function Definition

Unfortunately, the accepted medical standards that apply for adults, such as EEG and cerebral blood flow (CBF) measurements, are not reliable in newborns because of the open fontanel and lack of increase in intracranial pressures as seen in adults. Therefore, it has been suggested that in newborns, we may need to consider 'brainstem death' rather than brain death3 in the evaluation of coma.

Development of cardiorespiratory support in neonatal intensive care units (NICU's), arouse the need to define BD criteria in newborns.BD diagnosis is vital for parents and medical staff to help them decide if a newborn should be supported further or not

In neonatal units, the percentage of BD among deaths has been found 1 – 6.3%.BD newborns are comatose, apneic with their brainstem reflexes absent. It is of great importance to confirm BD in newborns with serial clinical neurologic examinations and ancillary tests.

BD criteria for infants <2 months remain controversial while in older children and adults have been well established BD criteria

1987's BD guidelines for children younger than 1 year of age in United States, were recently revised in 2011 by Nakagawa et al. These guidelines are based in definition of coma cause, irreversible cessation of entire brain's function (specifically brain stem), exclusion of reversible causes, clinical neurological examination criteria, neurodiagnostic tests and suggestion of specific observational periods according to age

Brain death guidelines in children (modified form from Ad Hoc Task Force guidelines for the determination. of brain death in children).

Brain dead patients supported on mechanical ventilation, are comatose, apneic and lack brain stem reflexes. BD diagnosis requires clarification of: Etiology, clinical examination, apnea and ancillary testing. Before determination for BD diagnosis, reversible conditions such as hypothermia, fluid and electrolyte abnormalities, altered metabolic status, hypotension, surgically curable conditions and exposure to toxins / medications should be treated and excluded. Diagnosis

causes Common causes of BD in neonates are: perinatal asphyxia birth trauma central nervous system (CNS) infection malformations severe intracranial hemorrhage (intraventricular hemorrhage grade IV) metabolic diseases causes

Tests for brain death in newborns Neurological examination Apnea testing Duration of the observation period Diagnostic studies Tests for brain death in newborns

Neurological examination A careful neurological examination should be performed to document complete lack of responsiveness rather than subtle conscious behaviors. Assessment of brainstem function and absence of brainstem reflexes should be documented. Brain-stem reflexes are generally present in infants by 32 weeks gestational age. Neurological examination

oculocephalic (Doll's eye) reflex and oculovestibular (Caloric) reflex should both be examined. While performing neurological examination, it is essential to ensure that the examination is not compromised by pharmacologic effects of anticonvulsants such as phenobarbital or other sedatives.

Typically, oxygen should be preadministered for 10 minutes while the infant is on the ventilator, then the ventilator should be discontinued allowing the CO2 to rise. Oxygen supplementation should be continued while the infant is weaned from the ventilator. The threshold for CO2 is 60 torr for newborn infants. At this point, there should be a lack of sustained respiratory effort. Few ineffectual respiratory efforts should not be considered reversible brain defect.Carbon dioxide accumulates slowly in brain dead infants owing to lack of production of CO2 by the brain.Generally, this test should take five to 15 min to reach the CO2 threshold of 60 torr Apnea testing

Duration of the observation period The average duration to confirm brain death in infants less than seven days would be 24 to 48 hours. Duration of the observation period

The diagnostic studies commonly performed are electroencephalogram (EEG) and cerebral blood flow (CBF) studies. Diagnostic studies

Determination of brain death in the newborn requires repeated clinical examination with particular attention given to determine the cause of coma. Neurological examination is also pertinent, particularly with regard to brain-stem reflexes. Apnea testing should be performed as described earlier. EEG and CBF studies may not show abnormalities that are described in older patients. An observation period of 24 to 48 hours is recommended. If the EEG is isoelectric or if CBF is absent, the observational period can be shortened. Consideration should also be given to religious, cultural, legal and ethical issues when determining brain death in the newborn Conclusion