BT411 Lecture 3 Summer 2024 PDF

Brain Death It can be confusing to be told: Someone has brain death, because their life support machine will keep their heart beating and their chest will still rise and fall with every breath from the ventilator. But they will not ever regain consciousness or start breathing on their ow...

Brain Death It can be confusing to be told: Someone has brain death, because their life support machine will keep their heart beating and their chest will still rise and fall with every breath from the ventilator. But they will not ever regain consciousness or start breathing on their own again. They have already died.  Brain Death A person who is brain dead is legally confirmed as dead.  He has no chance of recovery because his body is unable to survive without artificial life support.  Brain Death Brain death (also known as brain stem death) is defined as: The irreversible loss of all functions of the brain. Brain Stem Death  The brainstem is the distal part of the brain that is made up of the midbrain, pons, and medulla oblongata. Each of the three components has its own unique structure and function. The brain stem is responsible for regulating most of the body's automatic functions that are essential for life. These include: 1. breathing 2. heartbeat 3. blood pressure 4. blood temperature  Also, the brain stem relays information to and from the brain to the rest of the body, so it plays an important role in the brain’s core functions. If the brain stem stops working, the person will never be able to be conscious or breathe without a machine (ventilator). A person is confirmed as being dead when the brain stem stops working. Vegetative State  What Does It Mean to Be in a Vegetative State?? A vegetative state, or “unaware and unresponsive state”, is a specific neurological diagnosis in which a person has a functioning brain stem, but no consciousness or cognitive function. A vegetative state can be caused due to acute brain damage which results from illness or injury. A person in a vegetative state has no cognitive function, or ability to think. But since his brain stem is still functioning, the person may: 1. regulate breathing and heart rate without assistance 2. open his eyes 3. has a sleep-wake cycle (sleep-wake cycle refers to our 24- hour daily sleep pattern which consists of approximately16 hours of daytime wakefulness and 8 hours of night-time sleep.) He’s not able to: 1. follow objects with his eyes 2. speak or respond to voices or verbal commands 3. interact with his surroundings 4. show signs of emotion 5. show signs of awareness How the Vegetative state is diagnosed? Diagnosis of the vegetative (unaware and unresponsive) state requires: 1. no language expression 2. no evidence of voluntary response to stimulation of sight, sound, smell, or touch 3. a functioning brain stem (detected from MRI scan) Is there a treatment for the vegetative state?  There’s no real treatment.  Rather, the focus is supportive care so the brain can heal.  Supportive care may involve: a feeding tube to provide nutrients changing positions on a regular basis to avoid pressure sores (bedsores) physical therapy to gently exercise the joints skin care and oral care Causes of brain death  Causes of brain death (brain stem death) Brain death can happen due to several causes as: 1. Heart attack 2. Cardiac arrest 3. Stroke 4. Infections (such as encephalitis) 5. Brain tumors  1. Heart attack  A heart attack occurs when an artery that sends blood and oxygen to the heart, is blocked.  The blockage is usually due to a buildup of fat, cholesterol and other substances in the heart arteries (coronary arteries).  The fatty, cholesterol-containing deposits are called plaques.  The process of plaque buildup is called atherosclerosis.  At any time, these plaques can rupture, causing the platelets in the blood stream to form a clot.  1. Heart attack  The platelets sense the plaque rupture and are confused, thinking that an injury has taken place that will cause bleeding, and instead of sealing the vessel to prevent bleeding as would occur with a cut, a clot forms in an intact blood vessel, causing a blockage of blood flow.  Without blood, a portion of the heart muscle can die, leading to a heart attack and the heart can't pump blood to the brain.  2. Cardiac arrest  Cardiac arrest isn't the same as a heart attack. A heart attack happens when blood flow to a part of the heart is blocked.  Cardiac arrest is not due to a blockage. However, a heart attack can cause a change in the heart's electrical activity that leads to sudden cardiac arrest.  2. Cardiac arrest  Cardiac arrest is defined as the sudden loss of all heart activity due to an irregular heart rhythm.  This can be caused due to several abnormal heart conditions. With its pumping action disrupted, the heart can't pump blood to the brain and other organs. When this occurs, a person loses consciousness and has no pulse. Death occurs within minutes if the victim doesn't receive treatment.  3. Stroke A stroke can occur when blood flow to the brain is blocked or there is sudden bleeding in the brain.  There are two types of strokes: 1. A stroke that occurs because blood flow to the brain is blocked is called an ischemic stroke. The brain cannot get oxygen and nutrients from the blood. Without oxygen and nutrients, brain cells begin to die within minutes. 2. A stroke that occurs because of sudden bleeding in the brain is called a hemorrhagic stroke. The leaked blood results in pressure on brain cells, damaging them.  The most common type of stroke is ischemic stroke.  4. Encephalitis  Encephalitis is an inflammation of the brain. There are several causes, including viral infection, autoimmune inflammation, bacterial infection, insect bites and others.  When inflammation is caused by an infection in the brain, it's known as infectious encephalitis.  And when it's caused by your own immune system attacking the brain, it's known as autoimmune encephalitis.  Sometimes there is no known cause.  5. Brain Tumors A brain tumor (known as an intracranial tumor) is an abnormal mass of tissue in which cells grow and multiply uncontrollably.  Brain tumors can happen in the brain tissue.  Brain tumors also can happen near the brain tissue; Nearby locations include nerves, the pituitary gland, the pineal gland, and the membranes that cover the surface of the brain. Brain death diagnosis  Brain death diagnosis Brain death diagnosis requires the presence of 3 conditions: 1. persistent (irreversible) coma. 2. absence of brainstem reflexes. 3. lack of ability to breathe independently (i.e.: Apnea).  1. Coma A coma is a state of unconsciousness, where a person is unresponsive and cannot be woken, even with stimulation such as the pressure on the supraorbital nerve.  Causes of Coma  It can have a variety of causes, including traumatic head injury, stroke, brain tumor, or drug or alcohol intoxication.  A coma may even be caused by illness, such as diabetes or an infection.  A coma doesn't usually last longer than several weeks (i.e., 3 weeks).  People who are unconscious for a longer time might transition to brain death.  2. Absence of brain stem reflexes (Lazarus sign)  The Lazarus sign or Lazarus reflex is a reflex movement in brain-dead patients, which causes them to briefly raise their arms and drop them crossed on their chests (in a position like some Egyptian mummies).  Like the knee jerk reflex, the Lazarus sign is an example of a reflex mediated by a neural pathway which passes via the spinal column but not through the brain.  Consequently, the movement is possible in brain-dead patients whose organs have been kept functioning by life-support machines.  3. Apnea Apnea is defined as the inability of the patient to breathe unaided (i.e., with no life support systems like ventilators). Apnea can be assessed by disconnecting the ventilator. If respiratory movements are absent, the apnea test supports the diagnosis of brain death. Lazarus Sign demonstrating video: https://www.bing.com/videos/search?q=lazarus+sign&& view=detail&mid=ADA46D8618C7DA8ACF5CADA46D86 18C7DA8ACF5C&&FORM=VRDGAR&ru=%2Fvideos%2Fse arch%3Fq%3Dlazarus%2Bsign%26FORM%3DHDRSC4 Cardiopulmonary resuscitation (CPR)  Cardiopulmonary resuscitation (CPR)  Is an emergency procedure consisting of chest compressions often combined with artificial ventilation in an effort to manually preserve intact brain function, until further measures are taken to restore spontaneous blood circulation and breathing, in a person who is in cardiac arrest.  It is recommended in those who are unresponsive with no breathing or abnormal breathing.  The rescuer provide artificial ventilation by either exhaling air into the subject's mouth (mouth-to- mouth resuscitation) or using a device that pushes air into the subject's lungs (mechanical ventilation).  The main purpose of CPR is to restore partial flow of oxygenated blood to the brain and the heart.  The objective is to delay tissue death.  Administration of an electric shock to the subject's heart, is usually needed to restore the viable heart rhythm.  CPR is continued until the person has a return of spontaneous circulation or is dead.  Defibrillators  Defibrillators are the devices which produce electric shocks that can restore the normal heart function of the victim. CPR demonstrating video: https://www.youtube.com/ watch?v=-NodDRTsV88