coma
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GC: n

S: BrainFoundation – https://goo.gl/JppGfP (last access: 12 November 2017); The Guardian – https://goo.gl/f83fqD (last access: 12 November 2017); NINDS – https://goo.gl/6TQXt8 (last access: 12 November 2017).

N: 1. 1640s. State of prolonged unconsciousness, from Latinized form of Greek Κῶμα, koma, (from the genitive form komatos) “deep sleep,” which is of uncertain origin. A term for “coma” in Middle English was false sleep in the late 14th Century.
2. Coma is a state of extreme unresponsiveness, in which an individual exhibits no voluntary movement or behaviour. Furthermore, in a deep coma, even painful stimuli (actions which, when performed on a healthy individual, result in reactions) are unable to affect any response, and normal reflexes may be lost.
3. There are many metabolic causes of coma, including:

  • A decrease in the delivery to the brain of substances necessary for appropriate brain functioning, such as oxygen, glucose (sugar), and sodium.
  • The presence of certain substances that disrupt the functioning of neurons. Drugs or alcohol in toxic quantities can result in neuronal dysfunction, as can substances normally found in the body, but that, due to some diseased state, accumulate at toxic levels. Accumulated substances that might cause coma include ammonia due to liver disease, ketones due to uncontrolled diabetes, or carbon dioxide due to a severe asthma attack.
  • The changes in chemical levels in the brain due to the electrical derangements caused by seizures.

4. A diabetic coma is a life-threatening diabetes complication that causes unconsciousness. If someone has diabetes, dangerously high blood sugar (hyperglycemia) or dangerously low blood sugar (hypoglycemia) can lead to a diabetic coma.
5. Depending on the cause of a coma, people who are in a persistent vegetative state for more than one year are extremely unlikely to awaken.
6. A medically induced coma is when a patient receives a controlled dose of an anesthetic, typically propofol, pentobarbital or thiopental, to cause a temporary coma or a deep state of unconsciousness. This type of coma is used to protect the brain from swelling by reducing the metabolic rate of brain tissue, as well as the cerebral blood flow. Throughout a medically induced coma, a patient’s critical life functions are constantly monitored by an anaesthesiologist or other physician in a critical care setting only.
7. It is also important to add the difference between induced coma and sedation. While a medically induced coma puts a patient in a very deep unconscious state, sedation puts a patient in a semi-conscious state. Sedation is often given to allow a patient to be comfortable during a surgical or medical procedure and is administered through an intravenous catheter, with minimal side effects. A medically induced coma is only administered in intensive care units, whereas sedation can be administered not only in hospitals, but ambulatory surgery centres and doctors’ or dentists’ offices.
8. Cultural Interrelation: We can mention the bestseller thriller novel Coma (1977) written by Robin Cook. This novel has inspired the film Coma (1978) by the director Michael Crichton and a TV serial of 2 episodes named Coma (2012).
In relation to the real cases where people suffered from coma we can find:

  • Kurt Cobain, an American singer-songwriter, best known as the lead singer and guitarist of the grunge band Nirvana, suffered from semi-coma in Rome because of a combination of champagne and legal painkillers.
  • Stevie Wonder, an American singer-songwriter and activist, suffered from a coma after a car accident in 1973.

S: 1. OED – https://www.etymonline.com/word/coma (last access: 12 November 2017). 2 & 3. MEDICALDICT – https://goo.gl/T1Hz3x (last access: 12 November 2017). 4 & 5. MAYO – https://goo.gl/xx94Vd (last access: 12 November 2017). 6 & 7. ASAHQ – https://goo.gl/8C92Cb (last access: 12 November 2017). 8. INDEP – https://goo.gl/eJUdbH (last access: 12 November 2017); LISTVERSE – https://goo.gl/TAsP28 (last access: 12 November 2017).

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CR: brain death, symptom, traumatic brain injury.