Death occurs when a living organism (a person for example) can no longer independently maintain the essential body functions (breathing, a beating heart, etc.) that are necessary to keep the person as a whole alive. As a general rule, death occurs when the body can no longer supply its vital organs, like the heart, the lungs, and the kidneys, with enough oxygen to keep these organs going. This lack of oxygen, termed hypoxia in medicalese, can occur for multiple, multiple different reasons. For example, a person with severe lung disease might die from hypoxia because they can’t effectively breath whereas a person who has suffered a massive heart attack is at risk of dying because their heart can’t circulate oxygen (from the lungs) through the blood to reach the other vital organs –different mechanisms causing organ hypoxia, but with the same end result.
An Egyptian mummy. If only it were always so obvious when people are dead my job would be much easier…
The reason that oxygen is important to the body is because it is used to “burn” the biological fuels that we all obtain by eating to produce the energy that body tissues need to stay alive — no energy, no life. Different organs die at different rates when they don’t get enough oxygen. For instance, the brain begins to die after about 4 minutes of oxygen deprivation whereas skeletal muscle (your biceps muscles for example) can last for up to 4 hours without an adequate oxygen supply — a really big difference!
An image of human cells growing in a laboratory. These are HeLa cells, cells which were taken from Henrietta Lacks’ fatal tumor before her death in 1951 (without her consent) and have since become the standard human laboratory cell for study. No one objects to disposing of old HeLa cells, but the individual cells are very much alive, another excellent demonstration of why the distinction between life and death isn’t quite as obvious as most would think.
Okay, hang in there because I’m going somewhere important with all of this. The concept of brain death didn’t exist until the advent of mechanical ventilation, aka: life support. Since the brain controls breathing, the blood pressure, and (indirectly) the heart, before the invention of life support a person with a nonfunctioning brain rapidly progressed to a state in which none of their other organs (lungs, heart, etc.) were working either — they were either obviously dead or they weren’t. Mechanical ventilation and other advanced intensive care techniques changed all of this by enabling physicians to artificially keep a persons heart and lungs working even if the brain was damaged beyond repair. This is because the brain is the first tissue to die when a person’s body has an inadequate supply of oxygen and sometimes physicians are able to treat people only after their brain has been irreparably damaged, but before their heart, lungs, kidneys, and other vital organs have begun the irreversible dying process. This scenario is really important for several reasons and more common than you might think.
A mechanically intubated American serviceman injured overseas and being prepared for brain surgery. The tube coming out of his mouth continues down his trachea (the airway) and is attached at the other end to a mechanical ventilator. The black device on his head is used during neurosurgery to precisely localize portions of the brain in the operating room.
Because keeping a person’s body breathing on a ventilator when their brain is irreversibly destroyed makes absolutely no sense, physicians began contemplating the need for a diagnosis (that did not exist at the time) to convey to patient’s families the irreversible nature of the damage to their loved one so that they wouldn’t suffer from delusions of false hope and so that limited Intensive Care Unit beds wouldn’t be taken up by patients with no chance of recovery (and therefore possibly denied to other patients who might recover due to lack of beds). The answer to this conundrum was the development of the concept of “brain death” by the medical community, a concept that met great resistance from some quarters and which was highly controversial outside of the world of medicine until at least the mid-1970s, nearly three decades after mechanical ventilation became a common place treatment in intensive care units.
In 1954 the world’s first successful internal organ transplantation occurred (it was a kidney transplant that was performed in The United Kingdom) and over the next three decades organ transplantation became widespread, saving thousands upon thousands of lives that otherwise would have ended prematurely. Because brain dead patient’s often have little wrong with their other vital organs, at least in the first few hours-to-days, people who have suffered brain death are the source a very large proportion of donor organs. This is because many cases of brain death are caused by head trauma and many head trauma victims are young people with otherwise extremely healthy organs (you wouldn’t want a kidney transplant from a dead elderly person whose kidney’s had been damaged over the years from diabetes and high blood pressure, right!). The fact that brain dead patient’s have no chance of recovery, coupled with the fact that their internal organs can potentially save the lives of many others, led the Federal Government in The United States to finally get off its butt and propose national standards for the determination of brain death, standards which were approved in 1980 and soon thereafter adopted by an overwhelming majority of the 50 States.
The fluid-filled abdomen of a man with end-stage cirrhosis. A liver transplant would likely save his life. Not all cirrhosis is caused by alcohol, by the way. Genetic diseases, drug reactions, and autoimmune diseases can all destroy the liver as well.
Before we delve deeper, let’s briefly look at the 5 categories of Altered Levels of Consciousness: Confusion, Delirium, Obtundation, Stupor, and Coma. A confused person is mildly disoriented while a delirious person is completely disoriented and also may have both hallucinations (e.g. hearing voices or seeing things that do not exists) and delusions (e.g. thinking that the nursing staff is trying to kill them). An obtunded person is sleeping but you can wake them, at least for a little whle, by talking to them or with other gentle stimuli, for instance by nudging their shoulder. Patients in a stupor can only be aroused by causing pain and a very common way to do this in the hospital is to forcefully rub the patient’s breastbone with your knuckles or to press down hard onto one of their fingernails with pen or with the metal shaft of a reflex hammer. A person who is absolutely unable to be awakened is in a coma.
An obtunded cat, greatly in need of a referral to Alcoholics Anonymous. Let’s all pray for him tonight…
Okay, returning to brain death. All brain dead people are in a coma but not all people in a coma are brain dead. Coma’s have multiple causes and some are reversible while others are not. The first thing that a physician does when they evaluate a person who is potentially brain dead is to look for a known cause (e.g. a motorcycle/”donor cycle” accident in a person who wasn’t wearing a helmet). The next step is to rule out any potentially reversible, i.e. “fixable,” conditions that might be contributing to the patient being in a coma, especially drugs/alcohol, electrolyte abnormalities, and hypothermia — “you’re not dead until you’re warm and dead” — as the ER maxim goes.
As with all maxims, there are probably some reasonable exceptions to “you’re not dead until you’re warm and dead.” This is a frozen juvenile wholly mammoth fossil.
In order to be declared brain dead in The United States a person must undergo a thorough examination by at least two physicians. Both of these physicians perform an extensive neurological examination. Brain dead patient’s are unresponsive to painful or noxious stimuli above the neck, have unresponsive dilation of the pupils, no gag reflex, and do not breath spontaneously (as determined by a specialized “apnea test”). If all of these findings are consistent with the diagnosis of brain death on both physicians’ separate physical examinations then the patient can be declared dead.
A spinal reflex — no brain required.
Interestingly, brain dead patient’s often do have a response to painful stimuli below the neck and they can even move in response to it (e.g. moving an arm when it is stimulated). This is because the reflexes below the neck are controlled via the spinal cord and sometimes the spinal cord takes longer to die than the brain. Another interesting category of patients is people who have obviously suffered a brain injury that is so severe that they are in an irreversible, permanent coma but who don’t meet the full criteria for brain death. These people are in a “vegetative state.” Vegetative states have a poor prognosis and people who have been in a vegetative state for greater then one year (like in the Terri Schiavo case) essentially have a zero percent chance of recovery.
The first take home message is to please treat your brain gently and wear a helmet, seatbelt, and other commonsense safety equipment when engaging in activities that can result in head injury such as skateboarding, riding a bicycle, and driving an automobile. The second take home message is to please consider signing an advance directive with your family and physician so that your wishes are known as to the extent of treatment that you would desire if you were to suffer a severe brain injury (would you want to be an organ donor and potentially save someone’s life?). We all live in a dangerous world full of automobiles driven by distracted drivers — think ahead and spare your family the agony of having to make difficult decisions for you without knowing what your wishes would have been.
Three people on a motorcycle without helmets, a fantastic example of a really bad idea!
Dr. Leonardo Noto
Physician and Author of Medical School 101, Intrusive Memory, The Life of a Colonial Fugitive, and The Cannabinoid Hypothesis. Amazon Link to Doc’s Writing: http://www.amazon.com/Leonardo-Noto/e/B00ATVOMCW/ref=ntt_dp_epwbk_0
NOTE: The Life of a Colonial Fugitive — my dark historical thriller — is free for your ereader at http://www.smashwords.com/books/view/215272. Thanks for reading!
Author Bio: Dr. Leonardo Noto is the nom de plume of a former airborne battalion surgeon who is now in civilian practice. Dr. Noto is the author of four books and he also writes for a medical education corporation that assists medical students, interns, and residents as they prepare for the medical board examinations. Dr. Noto is the proud father of an extremely spoiled 16-month-old American Bulldog who enjoys slobbering everywhere and tearing up things that he is not supposed to! Dr. Noto is an amateur practitioner of muay Thai and Brazilian jiu jitsu and he recently began learning to play the guitar (but he is currently a quite terrible musician, as his neighbors will readily attest).
Remember to discuss all health concerns with your personal physician (I don’t count!) before making any medical decisions. www.leonardonoto.com is intended to present general medical information for entertainment purposes and not as specific guide to any medical treatment. The author has made every effort to present accurate information; however, due to the ever-changing nature of medicine and the intrinsic caveats that are inherent in any particular case, no medical decisions should ever be made based on information gleaned from the internet (duh!). The internet and self-education are great, but they don’t replace your Doc!
The opinions voiced on this medical blog are solely the author’s own and they do not reflect the opinions or values of Dr. Noto’s employers, past or present. Dr. Noto’s medical blogs should never be used as supporting evidence for legal testimony — this is of course obvious to anyone who isn’t a complete moron, but some people are rather stupid.
Reynolds, NC. Special Issues in Medicolegal Neurology. In emedicine. http://emedicine.medscape.com. Sept. 16, 2009.
Young, BG. Diagnosis of Brain Death. In UpToDate. http://www.uptodate.com. May 17, 2012.
Determination of Death Act Summary. Uniform Law Commission. http://www.uniformlaws.org. 2013.
Loss of Consciousness. In PDR Health. http://www.pdrhealth.com/diseases/loss-of-consciousness.
First Successful Kidney Transplant Performed in 1954. In: A Science Odyssey — People and Discoveries. http://www.pbs.org.
The Multi-Society Task Force on PVS. Medical Aspects of the Persistent Vegetative State. N Engl J Med 1994; 330:1572-1579.
HeLa (Henrietta Lacks) Cells: http://en.wikipedia.org/wiki/File:HeLa_Cells_Image_3709-PH.jpg
Ventilated Head Trauma Patient: http://en.wikipedia.org/wiki/File:US_Navy_040723-N-8977L-008_Navy_Hospital_Corpsmen_and_Medical_Officers_assess_the_treatment_and_prognosis_of_a_patient_with_a_gunshot_wound.jpg
Hepatic Cirrhosis: http://en.wikipedia.org/wiki/File:Hepaticfailure.jpg
Burns, M. Cat with a Drinking Problem: http://www.flickr.com/photos/mike-burns/35538355/sizes/m/in/photostream/
Frozen Wholly Mammoth: http://en.wikipedia.org/wiki/File:Mamut_enano-Beringia_rusa-NOAA.jpg
Patellar Reflex: http://www.google.com/imgres?imgurl=&imgrefurl=http%3A%2F%2Fmeded.ucsd.edu%2Fclinicalmed%2Fneuro3.htm&h=0&w=0&sz=1&tbnid=TbeJEv9WUMdqNM&tbnh=259&tbnw=194&zoom=1&docid=pBB_SrdVm0_2QM&hl=en&ei=Rhs1Usm1GZPEqQGP4oH4CA&ved=0CAEQsCU