EVOLUTION OF THE CONCEPT OF BRAIN DEATH
The concept of Brain Death is very important for those involved in organ transplantation. It is a crucial as it is the first step towards organ retrieval and transplantation. Only when a patient is declared brain dead, can organ retrieval take place. Head injuries from road accidents can account for almost 50% of Brain Deaths. Other situations that can lead to brain death is a stroke or haemorrhage in the brain. Organ donation is an option for relatives of patients who are brain dead. Here is a brief history of how brain death came to identified and declared by doctors across the world.
Two French physicians in 1959 first recognized Brain Death on patients being ventilated in the intensive care units, and called it coma depasse (a state beyond coma). In 1968, an Ad Hoc Committee of Harvard Medical School defined brain death as irreversible coma with the patient being totally unreceptive and unresponsive with absence of all cranial reflexes and no spontaneous respiratory efforts during a 3 minutes period of disconnection from the ventilator. How much of brain needs to be actually dead before death can be diagnosed has been debated over the years. Experiments have shown that a few cubic centimetres of tissue called œbrainstem which is located beneath Aqueduct of Sylvius anteriorly and floor of fourth ventricle posteriorly is the vital section of the brain that determines consciousness and ability to breathe spontaneously. (This is the section of you head which is near your neck). Destruction of these tissues is what determines brain death. Once the brain stem dies, the whole brain dies.
However, in certain countries, the whole brain including the brainstem needs to die to diagnose the state of ‘irreversible death’ and requires four vessels (carotid and vertebral) angiography and Isotope studies of the cranium. This can be a cumbersome exercise to undertake in an intrinsically unstable patient. In contrast, the tests that determine brainstem death are more clinical and over the last 30 years have proven to be simple, clinical, fool proof and capable of confirmation. In 1988 the Irish working committee on Brain Death in its memorandum said, “if the brainstem is irreversibly lost, what goes on elsewhere in the brain is immaterial and Life cannot return”. In this situation the heart can continue to beat and keep the circulation of some of the essential organs, provided the patient is kept adequately ventilated and hemodynamic stable. However, this state can be only maintained temporarily and eventually cardiac a systole occurs in all the patients.
In the short time between the onset of brain death and cardiac death (when the heart also stops beating in addition to the brain being dead, which could be as less as a day or as much as 3-4 days), is the time that organs have to be retrieved and transplanted into waiting recipients. Countries around the world have developed their own systems that efficiently and transparently retrieve organs and transplant them into others. UNOS in the United States is one of them.
In India the story is different. India recognises brain death in the Transplantation of Human Organs Act of 1994. Regulatory authorities in each state are empowered to look into the whole process of organ donation for both live related (or unrelated) and cadaver organ donation and transplantation.
Unfortunately only three states – Tamil Nadu, Karnataka and Maharashtra have government run deceased organ donor networks that ensure that all hospitals are connected to a centralised waiting list and organs are distributed efficiently.
LEGAL ASPECTS IN BRAIN DEATH CERTIFICATION
According to the provisions of the Transplantation of Human Organs Act1, known as THOA, the protocol for declaration of brain death requires:
The certifying clinicians must have no interest or benefit in any way from transplantation of cadaver donor organs. The legal time of death in these circumstances is taken as the second set of brainstem death tests. The certification should be done on laid out forms as per the act. In a medico-legal case, a forensic expert is also required for the certification. The medical director or medical superintendent of the hospital should finally countercheck and sign the form. It is only after these formalities have been completed, should ventilatory support be discontinued or organs retrieved.
According to law, doctors are required to take the family members’ consent before retrieving organs, even if the brain-dead patient has pledged his or her organs. After the Transplantation of Human Organs Amendment Act, 2011 was implemented, the treating physician now has to examine the patient for being brain dead and if found so, he/she must sensitize and make the family aware about organ donation.
ESTABLISHING BRAIN DEATH DIAGNOSIS
The aim is to establish that the patient has absent brainstem reflexes and is apnoeic. 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 ventilator support. The cause of irreversible structural brain damage should be known. Functional reversible causes of a non-functioning brain stem should have been ruled out. These causes include.
Establishing loss of ‘Brainstem reflexes’ at the bedside: – Absence of brain stem function is essential for establishing the diagnosis of Brain death. In a brain stem dead patient cranial nerve reflexes are tested to observe their motor response to a sensory input.
TESTS FOR ESTABLISHING BRAIN DEATH
The absence of brain stem function is documented by conducting the following five tests:
Pupillary Reflexes: To check for absent pupillary response to light, bright pen torchlight should be used 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: Moist cotton tipped swab should be used and firm pressure should be applied to the cornea without damaging it.
Vestibulo-ocular Reflexes: 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 Reflexes Test: requires temporary disconnection from the ventilator. A 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 a painful stimulation: 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. Pin pricks should not be used to test this response.
Dolls Head 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 than other tests to establish brain death can be postponed. One may need to disconnect the patient from the ventilator for 15 to 20 second to perform this test. To do this test the physician holds the patients head between his hands and moves the head from side to side through1800. 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 noticed. 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 brain stem is still alive there will be an 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.
The plantar response: may continue to be present in brain death 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. This is the ultimate test to establish brainstem death. It demonstrates that the spontaneous respiratory response fails to occur even in the absence 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 increase at a rate of 2mm/min (0.3 kPa/min) during apnoea 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). However, a rise to 50mmHg in CO2 tension is acceptable and should provide sufficient stimulatory drive for spontaneous respiration in an intact respiratory centre. In patients with chronic airway disease or severe chest trauma, the apnoea test maybe difficult to perform.
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 brain stem death certification is required.
REQUEST FOR ORGAN DONATION
Brain death is relatively a new concept and making request for organ donation in these circumstances can be an extremely difficult task for a doctor or a nurse to undertake. If the decreased carries, a Donor Card (a card the size of a credit card expressing their desire about organ donation) the task of asking for organ donation becomes easier.
In Tamil Nadu a simple protocol was devised called Ramachandra Protocol when asking for organs. In this protocol Eyes ‘ were first requested for and only if the relatives agreed, other organs were asked for. In the tragic circumstance it was felt that by asking for the eyes first the relatives were less likely to get upset with a request for organ donation.
Usually the organ donation request is made in the time interval between the diagnosis of brain death and discontinuation of the ventilator. If the relatives are agreeable the process of organ donation is under taken and vital organ like heart, lungs, liver, pancreas and kidneys are removed for transplantation. Corneas should be kept moist and eyelids should be closed and retrieval surgery can be done for up to 12 hours after cardiac standstill. Other tissues like heart valves, skin, bone and cartilages can be removed for up to 48 hrs after death. The process of organ donation and transplantation requires co-ordination between different teams operating almost simultaneously and sometimes in different locations. It may require getting surgeons from different specialties together for both donor and recipient surgery.
Generally, there is no bar to organ donation and one or the other organ or tissues can be donated at any age. However, it is important to do some essential virology screening before accepting the donor. All potential donors will require a virology screen to prevent possible transmission of disease from donor to the recipient. The next of kin should be made aware that this is necessary; if there are any objections these should be respected. However, it does mean that donation cannot then take place.
Brain Death – Your questions answered