Brain Death – Identification & Certification
Dr.Sunil Shroff. Managing Trustee Mohan Foundation
Organ transplantation has been one of the greatest advances of modern science that has resulted in many patients getting a renewed lease of life. It was included in the top five medical miracles of the last century. Transplantation would not be possible but for organ donation. Organs can be donated by a living person, after natural death and after “Brain death”. Brain death is a relatively new concept of death that was first recognized in Paris in 1959. The Government of India recognized this as a legal form of death in 1994 and passed an Act called the “Transplantation of Human Organs (THO) Act”. This legislation was also enacted to streamline the activities of living transplants especially kidneys. This kind of transplant has achieved considerable notoriety in India with frequent commercial organ scandals where the brokerage for kidneys can be considerable leading to exploitation of the poor in the country. The Govt. through this act wished to wipe away this practice by making it illegal and a punishable offence.
Since this Act was passed it has been possible to undertake multi-organ transplant activity from brain dead donors in India. After natural death, only a few tissues can be donated (like cornea, bone, skin and blood vessels) whereas after brain death almost all the organs and tissues can be donated including critical organs such as kidneys, heart, liver and lungs. At any given time, there are 8 to 10 brain dead patients in different Intensive Care Units (ICUs) in any major city of the country. We have 140,000 deaths from road traffic accidents every year. 67% of these patients suffer from head injury that leads on to brain death in many instances. We hence have potentially a huge pool of brain dead donors available in India. This pool of patients can easily meet the demand for organs not only for our country but also perhaps our neighboring SAARC countries and help in wiping out the shortage of organs and hence the commerce in kidneys, which continues to haunt the country despite the legislation which has been in force now for fifteen years. Almost, 85% of all transplants done across the world originate from organs from brain dead donors.
The Critical Care clinicians and nursing staff form an important section whose input in the intensive care is essential for the success of such a programme. The brain dead patient is an intrinsically a hemodynamically unstable patient. Therefore, once the family agrees to donate the organs, it is paramount to keep these unstable patients in a state to make organ retrieval possible and keep the organs in optimum working condition to be used for a recipient. This chapter aims to provide an overall perspective of this theme and wish to sensitise these key personnel on these issues.
Establishing Brain Death Diagnosis
The aim is to establish that the patient has absent brainstem reflexes and is apneic. The testing itself is straightforward. There are certain preconditions that should have been fulfilled to make sure that the tests are performed on the right patients and at the right time. These are as follows:
Patient should be comatose and on ventilatory support.
The cause of irreversible structural brain damage should be known –
Functional reversible causes of a non-functioning brainstem should have been ruled out. These causes include.
- Primary Hypothermia
- Alcohol intoxication
- Neuromuscular blockades (like use of muscle relaxants)
- Use of central nervous system depressant drugs like use of sedatives
- Severe metabolic or endocrinal disturbances.
- Patient should have no circulating therapeutic levels of any drug that could cause coma
Establishing loss of ‘Brainstem reflexes’ at the bedside – Absence of brain stem function is essential for establishing the diagnosis of Brain death (Fig -2). In a brain stem dead patient cranial nerve reflexes (Table-II) are tested to observe their motor response to a sensory input. The absence of brain stem function is documented by conducting the following five tests:
- Absence of Pupillary reflex – response to light
- Absence of Corneal reflexes
- Absence of vestibulo-ocular reflex
- Absence of cranial nerve response to pain
- Absence of gag and cough reflexes
Pupillary Reflexes: To check for absent pupillary response to light, bright pen torchlight should be shone into each eye in a darkened room. It should be made sure that no eye drops to dilate the pupils have been used in the four hours previously. The pupils may not be necessarily fixed and dilated in the brainstem dead patients, however there should be no pupillary response to light.
Corneal Reflexes:A moist cotton tipped swab should be used and firm pressure should be applied to the cornea without damaging it.
Vestibulo-ocular Reflexes: This testing involves instilling 20ml of ice-cold water into the external auditory canal and looking at eyeball movements of either eye for about a minute. No eyeball movement indicates absence of reflex. Presence of ruptured eardrums or discharge from the ear prevents this test from being performed.
‘Gag and Cough Reflex’ Test: This requires temporary disconnection from the ventilator. Cotton tipped swab can be used to stimulate the posterior pharynx to look for a response. Experienced ICU staff usually notice a progressive loss of response during the evolution of brainstem death when performing the routine suction of airways and oropharynx.
Grimacing of the face to painful stimulation: This is a normal response and this is absent in brainstem death situation. A firm supra-orbital pressure (trigeminal nerve) should be used to check this cranial reflex. Pinpricks should not be used to test this response.
Doll’s Eye Phenomenon (testing for oculo-cephalic reflex): This is one test that can be done to know if the brainstem is still alive. If this test is positive then other tests to establish brain death can be postponed. One may need to disconnect the patient from the ventilator for 15 to 20 seconds to perform this test. To do this test the physician holds the patient’s head between his hands and moves the head from side to side through 180 degrees. The clinician should hold the head to one side for 3 to 4 seconds and look at the simultaneous eye movement to that side. A similar movement is done to the opposite side and eye movement is observed. In a normal fully alert individual and in a cadaver the eyes move with the head and there is only a very fractional delay. If the cerebral hemispheres are damaged but brainstem is still alive there will be a obvious deviation of the eyes to the opposite side for a second or two followed by a “release phenomenon” when the eyes will get realigned to the side of the head. This test should not be done if cervical fracture is suspected.
Plantar response:Thismay continue to be present in brain dead patients along with spinal reflexes and should not be tested. The decorticate and decerebrate posturing is absent, however on occasions it may be difficult to differentiate these from complex spinal reflexes.
Apnoea Test:The aim of apnoea test is to establish death of the respiratory centre in the brainstem (Table III). This is the ultimate test to establish brainstem death. It demonstrates that the spontaneous respiratory response fails to occur even in the presence of stimulatory drive from CO2. For this test the patient is disconnected from the ventilator for 10 minutes. However, to avoid hypoxia to vital organs, 100% oxygen is given for 5 minutes before disconnection from the ventilator. Even during the test period, 100% oxygen is given through a tracheal catheter. In the patient who is brain dead the carbon dioxide tension increases at a rate of 2 mmHg/min (0.3 kPa/min) during apnea testing. If the initial CO2 tension before testing is about 40mmHg (5.3 kPa) then arterial CO2 tension after 10 minutes is likely to be 60mmHg (8 kPa). In patients with chronic airway disease or severe chest trauma, the apnoea test may be difficult to perform.
Role of Cerebral Angiography & EEG for brain death testing:Four-vessel angiography is used to show absence of cerebral blood flow and confirm death of whole brain. However, this test is not done routinely as it is a cumbersome investigation to undertake in an unstable patient. Nor is it necessary to use EEG to diagnose the condition. If there is any doubt in the diagnosis of brain death one should not proceed for a request for organ donation and ventilatory support should be continued. In case of severe facial trauma or presence of paralyses or severe chest trauma, routine tests may not be possible and one may be required to do special tests like isotope scanning or Colour flow duplex scanning of the cranium to confirm brain death. All these tests can have limitations and can sometimes be inconclusive. In these inconclusive situations, if organ donation is being contemplated, the patient’s relatives should be told about it and the ventilator should only be disconnected in the operation theatre and organ retrieval started only after cardiac standstill. The Transplantation of Human Organ act does not require investigations like cerebral angiography or EEG for brain death certification, however they may substantiate the diagnosis of brain death in special circumstances.
In children, there remains uncertainty about the reliability of clinical brainstem testing. In neonates especially, organs for transplantation should not be removed in the first seven days of life with beating hearts. Radioisotope brain scanning has been recommended under the age of one year when brainstem death certification is required.