DEATH CRITERIA AND BRAIN DEATH

The issue that ‘when to declare a PICU baby dead' is highly complex with ethical and medicolegal dimensions. Death is defined as permanent cessation of organism as a whole (and not of the whole organism, i.e.

Brain death denotes irreversible cessation of all functions of the entire brain, including the brainstem with no chances of revival and survival without external support. The concept of the Brain death is important for the purpose of organ retrieval in cadaveric donations and organ transplant. In children, brain death usually occurs following traumatic brain injury and asphyxia.

Criteria: Brain death is primarily a clinical diagnosis based on at least two evaluations at least 24-hours apart, preferably supported by flat isoelectrical EEG or other

TABLE 27.19: Criteria for brain death*

(All of the following for gt;24 hours)

• Presence of definite coma

- No spontaneous movements or communication

- No response to external, even noxious, stimuli**

- No decerebrate or decorticate posture

• Absence of brain-stem reflexes, e.g.

- Fixed dilated pupils

- No oculocephalic, vestibular, corneal, gag reflex

• Positive apnea test

• Flat or isolectric EEG

• Absence of reversible causes, e.g. drugs, toxins, shock, etc. *Based on American Academy of Pediatrics, et al. Guidelines 2011. **Presence of spinal reflexes do not preclude diagnosis of brain death.

ancillary tests (Table 27.19). Potentially reversible causes of coma, e.g. metabolic disorders, drugs and toxins, hypothermia, hypoxia, shock, etc. must be excluded.

Apnea test is used to confirm the inability of the medulla to drive ventilation in cases of brain death, i.e. absence of respiratory efforts despite controlled stimulus, i.e. critical hypercarbia.

Considering the potential risk of destabilizing the patient, apnea test must be performed only if the first two criteria for brain death (irreversible coma and absence of brain-stem reflexes) are fulfilled, along with—(a) core temperature gt;35°C, (b) normal blood pressure, (c) not on sedatives or neuromuscular blocking medications,

(d) absence of severe electrolyte, blood gas or metabolic abnormalities.

For this test, patient is first ventilated with 100% oxygen to achieve a pCO₂ of ~40 mm Hg on baseline blood gas analysis. Subsequently, ventilatory support is withdrawn and blood gas analysis is repeated every 5 minutes until the target pCO₂ is surpassed. Absence of respiratory efforts even after pCO₂ has crossed gt;60 mm Hg or gt;20 mm Hg above baseline, indicates positive apnea test. Patient should be closely monitored during the test for hemodynamic status and oxygen saturation and the test should be aborted, if patient becomes hypoxic or hypotensive.

According to Indian human organ transplant act 2014, two apnea tests are required at minimum 6 hours interval to declare brain death. Some ancillary tests, e.g. EEG, transcranial Doppler USG in young infants and cerebral angiography may also be required in infants lt;1 year.

Following a diagnosis of brain death, supportive care must continue till the family accepts it and makes final decision about potential organ donation.