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BRAIN DEATH PREPARED BY: NASIF YUSOPH ICU STAFF NURSE
Thursday, July 21, 2011 Definition of Brain Death: Brain death is the irreversible cessation of all functions of the entire brain including the brain-stem. . Permanent brain damage resulting in loss of brain function, manifested by cessation of breathing and other vital reflexes, unconsciousness with unresponsiveness to stimuli, absence of muscle activity, and a flat electroencephalogram for a predetermined length of time. Patients who are brain-dead may still exhibit normal function of the heart, lungs, and other vital organs if they are receiving artificial life support.
The diagnosis is made by clinical examination and objective investigations. The diagnosis of brain death can be made in every hospital with a well-functioning ICU and must be done as a part of the general management of any patient fulfilling the criteria of brain-death, irrespective of the issue of organ donation
Who is responsible for thediagnosis of brain death? It is mandatory that a neurologist, a neuro-surgeon, an internist, an ICU physician, an anesthesiologist, a pediatrician or a consultant physician with experience in evaluation of brain-dead patients performs the examinations. Neither a nephrologist nor a transplant surgeon should be involved in the establishment of diagnosis of brain death.
CAUSE OF BRAIN DEATH BRAIN OEDEMA Swelling can occur in specific locations or throughout the brain. It depends on the cause. Wherever it occurs, brain swelling increases the pressure inside your skull. That's known as intracranial pressure, or ICP. This pressure can prevent blood from flowing to your brain, which deprives your brain of the oxygen it needs to function. Swelling can also block other fluids from leaving your brain, making the swelling even worse. Damage or death of brain cells may result.
Traumatic brain injury (TBI): deceleration of the head can cause the injury. The most common causes of TBI include falls, vehicle crashes, being hit with or crashing into an object, and assaults. The initial injury can cause brain tissue to swell. In addition, broken pieces of bone can rupture blood vessels in any part of the head. The body's response to the injury may also increase swelling. Too much swelling may prevent fluids from leaving the brain.
Ischemic strokes Ischemic stroke is the most common type of stroke and is caused by a blood clot or blockage in or near the brain. The brain is unable to receive the blood and oxygen it needs to function. As a result, brain cells start to die. As the body responds, swelling occurs.
Brain (intracerebral) haemorrhages Haemorrhage refers to blood leaking from a blood vessel. Hemorrhagic strokes are the most common type of brain haemorrhage. They occur when blood vessels anywhere in the brain rupture. As blood leaks and the body responds, pressure builds inside the brain. High blood pressure is thought to be the most frequent cause of this kind of stroke. Haemorrhages in the brain can also be due to head injury, certain medications,
Brain abscesses commonly occur when bacteria or fungi infect part of the brain. Swelling and irritation (inflammation) develop in response to this infection. Infected brain cells, white blood cells, live and dead bacteria, and fungi collect in an area of the brain. Tissue forms around this area and creates a mass. While this immune response can protect the brain by isolating the infection, it can also do more harm than good. The brain swells. Because the skull cannot expand, the mass may put pressure on delicate brain tissue. Infected material can block the blood vessels of the brain
Thursday, July 21, 2011 Preconditions for the Diagnosis of Brain Death: Patient is in coma and the cause of coma has been firmly established. Patient has no spont. respiration and is supported by a ventilator. The event causing brain-death occurred at least six hours previously and the cause of death has been clearly determined (i.e., head trauma, brain hemorrhage, etc). Patient is not in cardiovascular shock. Obvious metabolic and endocrinal derangements have been corrected. No response to any kind of stimuli. Complete areflexia. However, simple spinal cord reflexes may be present.
Thursday, July 21, 2011 Exclusions: Patient should not be hypothermic. The core temperature must be above 35.5 C before testing for brain death. Patient is not receiving any sedatives, muscle relaxants, anticonvulsants, hypnotics, narcotics or anti-depressants. Blood levels of these drugs should be nil or insignificant if the patient was on any of these drugs previously or an interval of five days should lapse before testing for brain-death. Patients with metabolic and endocrine causes of coma should be excluded. Patient should not have any signof cerebral activity like decerebrate or decorticate posture and seizure activities.
Brain stem reflexes test to be done for potentially brain death patient These test have to be done in the following order If anyone of these reflexes is preserved there is no need to proceed further. Re-assessment to be done after 6 hours for adult,12 hours for children and 24 hours for infant Because as we grow older our brain tissue tolerance is decreasing
Brainstem - The lower extension of the brain where it connects to the spinal cord. Neurological functions located in the brainstem include those necessary for survival (breathing, digestion, heart rate, blood pressure) and for arousal (being awake and alert). Most of the cranial nerves come from the brainstem. The brainstem is the pathway for all fiber tracts passing up and down from peripheral nerves and spinal cord to the highest parts of the brain.
Medulla Oblongata - The medulla oblongata functions primarily as a relay station for the crossing of motor tracts between the spinal cord and the brain. It also contains the respiratory, vasomotor and cardiac centers, as well as many mechanisms for controlling reflex activities such as coughing, gagging, swallowing and vomiting.
Midbrain - The midbrain serves as the nerve pathway of the cerebral hemispheres and contains auditory and visual reflex centers.
Pons - The pons is a bridge-like structure which links different parts of the brain and serves as a relay station from the medulla to the higher cortical structures of the brain. It contains the respiratory center.
Thursday, July 21, 2011 Tests for Brain-stem reflexesa) Pupillary Response to light:Shine a bright beam of light from a suitable source, e.g., a pen flashlight, on to the open eyes. In a brain-dead patient, no response, neither direct nor consensual, is seen to the stimulus in either eye.Both eyes must be tested. Make sure that mydriatic or meiotic eye drops or drugs have not been used in the recent past prior to carrying out the test.
Thursday, July 21, 2011 Tests for Brain-stem reflexes b) Corneal Reflex:Touch the cornea with a wisp of cotton wool. If the brain stem is dead, no blinking response is noted on either side. The test should be performed on both sides.
Thursday, July 21, 2011 Tests for Brain-stem reflexes c) Oculo- Cephalic Reflex: Normally when the head is rotated from side to side, the eyes move in the opposite direction. However, in brain death the eyes move with the head in the same direction.
Thursday, July 21, 2011 Tests for Brain-stem reflexes d) Vestibulo- Ocular Reflex (Caloric Test): in normal caloric test, injection of 20 ml of iced cold water into the external auditory meatus leads to nystagmus of the eye into the other side. The test should be done on both sides. In brain death, no nystagmus.
Thursday, July 21, 2011 Tests for Brain-stem reflexes e) Upper and Lower Airways Stimulation (Gag and Cough Reflexes): Normally, stimulation of the pharynx, larynx and trachea by catheter leads to gagging or coughing. In brain death, no response.
Thursday, July 21, 2011 APNEA TEST - The patient is preoxygenated with 100% O2 for 5 min before disconnecting from ventilator. - During the period of apnea 4-6 lr /min of O2 is supplied via ETT suction catheter to avoid hypoxemia. - The test is considered +ve if no respiratory attempts were found while reaching a Pco2 of > 60 mmHg. - The test should be aborted if there was any hypoxemia during the test.
Thursday, July 21, 2011 Confirmatory Tests ELECTROENCEPHALOGRAPHY (EEG) - A minimum of eight scalp electrodes and ear lobe references covering the major brain areas shall be used - Should be tested for reactivity to loud noise Recording will be done for at least 30 minutes - Electromyographic artifacts can be seen sometimes in a patient with isoelectric EEG, neuromuscular blocking agents like pancuronium may be used, but during the recording only.