The Diagnosis Of Death
Table of Contents
Despite advances in medical technology, medical science can never achieve immortality.
Death indeed is the ultimate truth of life and we as pediatricians are quite used to facing children with acute catastrophic life-threatening diseases and terminal illnesses.
Many critically sick children are supported by artificial life-sustaining measures, like vasopressors and mechanical ventilation in whom criteria of brain death are used to declare them as dead even when their heart is beating.
Read and Learn More Pediatric Clinical Methods Notes
The prolonged and unnecessary maintenance of a “Dead” child on a life support
system is an extremely stressful experience for the parents and expensive for the state.
Accurate timing of brain death is also important to harness the organs of children, whose parents are willing, for cadaveric transplant of the heart, lungs, liver, and kidneys.
Following the enaction of the Human Organ Transplant Act by many countries, it is legally justified to remove organs from brain-dead patients who are still having heartbeats.
Death is diagnosed when a child has sustained either:
- Irreversible cessation of circulatory and respiratory functions or
- There is irreversible cessation of all functions of the entire brain including the brainstem.
- Irreversible coma and apnea must coexist, for the diagnosis of brain death.
- After the brain is dead and spontaneous respirations have ceased, the heart may continue to beat, if mechanical ventilation maintains adequate oxygenation of blood.
History
The probable cause of coma should be ascertained to ensure that there is no remediable or reversible condition.
Identify and exclude any potentially reversible toxic and metabolic disorder, use of sedative-hypnotic drugs or paralytic agents, hypothermia, drowning, hypoxia, trauma, electrocution, hypotension, and surgically correctable condition.
Cessation Of Circulation And Breathing Efforts
Vigorous cardiopulmonary resuscitation (CPR) should be continued for at least 30 minutes while continuously monitoring vital signs. The absence of heartbeats and spontaneous respiratory efforts during an appropriate period of observation (at least 30 min) is a satisfactory criterion of clinical death.
When a patient is attached to an ECG monitor, flat tracings are indicative of cellular death.The diagnosis of cessation of breathing poses practical difficulties in babies on a ventilator. The ventilator can be periodically switched off and spontaneous respiratory movements are watched.
It is essential to maintain the PaCO2 of the patient around 60 mm Hg or 20 mm Hg above the normal baseline value (so that there is enough drive for the respiratory center) before the ventilator is switched off.
Brain Death
The current legal definition of death requires clinical evidence of irreversible brainstem death. Coma and apnea must coexist to diagnose brain death. Hypotension, hypothermia, and metabolic disturbances that could affect the neurological examination must be corrected before evaluation of brain death.
Sedatives, anticonvulsants, and neuromuscular blockers should be discontinued for a reasonable time period, based on the elimination half-life of the pharmacologic agent, before conducting the neurologic examination for brain death. The clinical criteria for brain death are listed in.
In deeply comatose patients (absence of facial grimace on firm pressure over the supraorbital region), on assisted ventilation and advanced life support system, it is futile
to continue with life support measures, if neurologic functions have irreversibly ceased.
When brain death occurs, patients lose their brainstem reflexes in a rostral-to-caudal direction and the medulla oblongata is the last part of the brain that ceases to function. The cessation of neurologic functions is assessed by evaluation of
The following brainstem reflexes:
1. Pupillary response to light:
The pupils should be dilated (4 – 9 mm) at mid-position and fixed on both sides without any response to bright light. A magnifying glass with inbuilt light can be used to assess pupillary response to light.
It is mediated by components of the optic and oculomotor nerves located in the mesencephalon.
Clinical criteria for brain death in children:
- Irreversible coma
- Absence of motor responses to pain
- Absence of pupillary responses to light and pupils are fixed at mid position (4 – 6 mm)
Absence of corneal reflexes - Absence of caloric responses (vestibulo-ocular reflex)
- Absence of gag reflex or coughing in response to tracheal suctioning
- Absence of sucking and rooting reflexes
- Absence of respiratory drive at a PaCO2 of 60 mm Hg or 20 mm Hg above the normal baseline values
- Observation period between two evaluations on the basis of the child’s age. The second neurologic assessment should be done by a different attending physician but second apnea testing should be done by the same physician.
- Term baby up to 30 days: 24 hours
- >30 days to <18 years: 12 hours
- >18 years: Interval is optional
- Confirmatory tests (EEG and radionuclide cerebral blood flow).
- When clinical examination and apnea testing cannot be completed safely due to the underlying medical condition.
- When there is uncertainty about the result of a neurological examination.
- If medication effect is present.
- To reduce the inter-examination observation period.
Adapted from Nakagawa TA, Ashwal S, Mathur M, Mysore MR et al. Guidelines for the
determination of brain death in infants and children. An update of the 1987 Task Force Recommendations. Crit Care Med 2011, 39:2139–2155.
2. Corneal reflex:
The corneal reflex should be absent. The corneal reflex is elicited by touching the cornea with a wisp of cotton and observing the reflex closure of the eyelids. It is mediated by sensory (5th nerve) and motor (7th nerve) components having neuroanatomic centers within the pons.
3. Oculocephalic reflex or ‘Dolls’ head-eye-movements:
Oculocephalic reflex or ‘Dolls’ head-eye movements are elicited by rotation of the patient’s head from one side to the other or up and down with eyelids held open, hi a comatose child with the intact brainstem.
When the head is turned to one side and maintained in that position for a few seconds, there are conjugate movements of both eyes to the opposite side. When the oculocephalic reflex is affected, there is either no conjugate movements of the eyeballs or there are dysconjugate movements.
4. Vestibulo-ocular reflex:
The tympanic membranes must be intact and there should be no local trauma or cerumen (wax) in the ear canal before this reflex is elicited. The head should be kept at 30° to the horizontal plane unless contraindicated by a cervical spinal injury.
About 20 ml of ice-cold water is slowly injected into each auditory canal and directed towards the tympanic membrane. When the caloric response is intact there is a tonic deviation or nystagmic movements of both eyes towards the side being stimulated.
The absence of any response is indicative of brainstem dysfunction. Both oculocephalic and oculi-vestibular reflexes are mediated by fibers from the vestibular portion of the 8th nerve with nuclei in the pons.
From these pontine centers, impulses are conveyed to the 6th nerve nucleus through internuclear synapses, causing lateral movements of the eyes towards the side of the stimulus.
Synapses exist between the 6th nerve nucleus and the 3rd nerve nucleus through the medial longitudinal fasciculus coursing through pons and men cephalon, resulting in medial deviation of the eye on the contralateral side.
5. Facial response to pain:
There is no facial grimace when firm pressure is applied over the supraorbital nerve, temporomandibular joint, or nail bed of a finger.
6. Oropharyngeal reflex:
The gag reflex and cough reflex response to the suction of the oropharynx and trachea should be absent. The tracheal catheter should be advanced up to the level of carina followed by one or two suction attempts.
7. Absence of respiratory drive:
The patient should be pre oxygenated by giving 100% oxygen for 5–10 minutes before initiating the apnea test. There is no spontaneous breathing even when PaCO2 is kept around 60 mm Hg or 20 mm Hg above the normal baseline value. The protocol for the apnea test is shown below
Protocol for apnea testing:
- Core body temperature should be >36°C
- Systolic or mean arterial blood pressure should be within the normal range for the age
- A ventilator is adjusted to provide normocarbia (PaCO2 35 – 45 mm Hg)
- The patient is oxygenated with 100% Fi02 for ≥ 10 minutes
- Draw an arterial blood sample for baseline blood gases
- Provide oxygen through T-piece with CPAP at 10 cm H2O
- Connect a pulse oximeter
- Disconnect the ventilator and leave the patient off the ventilator for 8 – 10 minutes
- Observe the patient for spontaneous respiratory movements
- Measure PaO2, PaCO2, and pH at the end of 8 –10 minutes and reconnect the patient to the ventilator
- Record your observations and comments
The diagnosis of brain death is confirmed, if there are no respiratory movements at PaCO2 of ≥ 60 mm Hg or when it is raised ≥ 20 mm Hg above the baseline PaCO2 of the patient on two occasions.
Observation Period:
It must be remembered that spinal segmental responses and deep tendon jerks may persist even in the presence of brain death. The brainstem reflexes should be elicited in all comatose children before disconnecting the ventilator.
The criteria for brain death are not well-defined in preterm babies, hi newborn babies, two EEGs taken 24 hr apart should show electrocerebral silence or dynamic scan (133 xenon CT or PET) should demonstrate the absence of cerebral blood flow for more than one hour.
The cessation of all brain functions must persist for at least 24 hours, and 12 hours for infants up to one month, and older than one month, respectively.
The observation period may be reduced, if the EEG demonstrates electrocerebral silence or the cerebral radionuclide study does not visualize cerebral arteries.
The children with potentially reversible conditions, such as hypoxia, narcotic poisoning, carbon monoxide exposure, electrocution, exposure to severe cold, neuromuscular blockade, metabolic conditions, drowning, and trauma should be watched for a longer period of time.
Hypothermia following drowning or exposure to cold may be associated with a state of “Suspended animation” and is the commonest cause of erroneous diagnosis of death.
Confirmatory Tests:
The diagnosis of brain death is primarily clinical by evaluation of coma, apnea, and brainstem reflexes. No ancillary tests are required if clinical tests of brain death are unequivocal. Rarely, confirmatory laboratory tests are undertaken to confirm the diagnosis of death.
Brainstem evoked responses, radioisotope (technetium Tc 99m hexametazime) scintigraphy, bolus cerebral angiography, xenon CT, digital subtraction angiography, visualization of cerebral arterial pulsations by real-time transcranial ultrasonography are reliable criteria of brain death but they are of limited practical utility.
Four-vessel intracranial angiography is diagnostic of cessation of circulation to the brain but is cumbersome. Electroencephalography with a minimum of 8 electrodes should demonstrate electrical silence for at least 30 minutes.
Doppler determination of cerebral blood flow velocity and evoked potentials are being investigated for the diagnosis of ‘brain death’.
The treating physician must, however, satisfy himself with reasonable certainty that the patient’s vital functions pertaining to heart, lungs and even brain have irreversibly ceased before the tragic news of death is communicated to the parents.
The possible cause of death including predisposing or underlying conditions should be recorded in the death certificate.
Confirmatory tests for diagnosis of brain death:
- Electroencephalography:
- Recordings are obtained for at least 30 minutes with a 16- or 18-channel instrument.
- Interelectrode impedance should be between 100 and 10,000 Ω.
- The integrity of the entire recording system should be tested.
- The distance between electrodes should be at least 10 cm.
- The sensitivity should be increased to at least 2 μV for 30 minutes with the inclusion of appropriate calibrations.
- The high-frequency filter setting should not be set below 30 Hz, and the low-frequency setting should not be above 1 Hz.
- Electroencephalography should demonstrate a lack of reactivity to intense somatosensory or audiovisual stimuli.
- Cerebral angiography:
- The contrast medium should be injected under high pressure in both anterior and posterior circulation.
- No intracerebral filling should be detected at the level of entry of the carotid or vertebral artery to the skull.
- The external carotid circulation should be patent. The filling of the superior longitudinal sinus may be delayed.
- Transcranial Doppler ultrasonography (TCD):
- There should be bilateral insonation.
- The probe should be placed at the temporal bone above the zygomatic arch or the vertebrobasilar arteries through the suboccipital transcranial window.
- The abnormalities should include a lack of diastolic or reverberating flow and documentation of small systolic peaks in early systole.
- A finding of a complete absence of flow may not be reliable owing to inadequate transtemporal windows for insonation.
- Cerebral scintigraphy or radionuclide brain scan (technetium Tc 99m hexametazime):
- The isotope should be injected within 30 minutes after its reconstitution.
- A static image of 500,000 counts should be obtained at several time points, i.e. immediately, between 30 and 60 minutes later, and at 2 hours.
- A correct intravenous injection may be confirmed with additional images of the liver demonstrating uptake (optional).
- Brain death is confirmed, if there is no radionuclide localization in the middle cerebral, anterior cerebral and basilar artery territories of the cerebral hemispheres (Hollow skull phenomenon).
- No tracer is seen in the superior sagittal sinus although minimal tracer may come from the scalp.
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