irreversible coma

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a state of unconsciousness from which the patient cannot be aroused, even by powerful stimuli. Traumatic brain injuries are the most frequent cause; other causes include severe uncontrolled diabetes mellitus, liver disease, kidney disease, and neurologic conditions. Evaluation of a patient in a coma is comprehensive. The underlying cause should be identified so that appropriate treatment can be initiated. magnetic resonance imaging, electroencephalography, and brainstem auditory evoked potentials give information about electrical activity of the brain in a patient who is comatose, although the results are not predictive of recovery. Some patients are able to emerge from a coma. In others, the coma may progress to a persistent vegetative state in which the functions of the brainstem and circulation remain relatively intact or may be supported with assistive technologies. Patients in irreversible coma may meet the criteria of brain death.
Schematic representation of major brain stem reflexes used in coma examination. From Marx et al., 2002.
Patient Care. Assessment of the patient in a coma includes an evaluation of vital signs, determination of level of consciousness, neuromuscular responses, and reaction of the pupils to light. In most hospitals a standard form is used to measure and record the patient's responses to stimuli in objective terms. The glasgow coma scale is a standardized tool that aids in assessing a comatose patient and eliminates the use of ambiguous and easily misinterpreted terms such as unconscious and semicomatose. Additional assessment data are gathered relating to the underlying cause and the patient's immobility; these include evaluation of the gag and corneal reflexes. In the absence of gag reflex, regurgitation and aspiration are potential problems.

Abnormal rigidity and posturing in response to noxious stimuli are motor responses to coma. Decorticate rigidity is abnormal flexor posturing, with the arms, wrists, and fingers drawn up. The legs may be extended with plantar flexion. This type of rigidity usually indicates a lesion in the cerebral hemispheres or a disruption of the corticospinal tracts. Decerebrate rigidity is abnormal extensor posturing: in response to painful stimuli the extremities extend rigidly and the palms turn outward. This type of rigidity is indicative of damage to the brainstem and as a rule is a sign of greater cerebral impairment than is decorticate rigidity.

Comatose patients are predisposed to all the hazards of immobility, including impairment of skin integrity and development of pressure ulcers and contractures. A multidisciplinary, coordinated plan of care is essential. Families should be encouraged to be actively involved in care of the patient. The health care team should also recognize the family's need for support; the emotional and financial impacts of coma are usually significant.
alcoholic coma coma accompanying severe alcoholic intoxication.
alpha coma coma in which there are electroencephalographic findings of dominant alpha-wave activity.
diabetic coma the coma of severe diabetic acidosis; see also diabetes mellitus.
hepatic coma coma accompanying cerebral damage resulting from degeneration of liver cells, especially that associated with cirrhosis of the liver.
hyperglycemic hyperosmolar nonketotic coma (hyperosmolar nonketotic coma) see hyperglycemic hyperosmolar nonketotic coma.
irreversible coma brain death.
Kussmaul's coma the coma and air hunger of diabetic acidosis.
myxedema coma an often fatal complication of long-term hypothyroidism in which the patient is comatose with hypothermia, depression of respiration, bradycardia, and hypotension; usually seen in elderly patients during cold weather.
coma vigil locked-in syndrome.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

ir·re·ver·si·ble co·ma

(ir'rĕ-vĕr'si-bĕl kō'mă)
A state of profound unconsciousness that cannot be reversed. Cf. brain death.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
References in periodicals archive ?
Montero, "Irreversible coma, ergotamine, and ritonavir," Clinical Infectious Diseases, vol.
As a neurologist, he or she knew exactly what the irreversible coma was and how to make judgments to the cause of the coma.
The new Act deletes the outdated reference to "irreversible coma" in the section that a principal uses to indicate his or her preferences regarding the withholding or removal of life-sustaining treatment.
CPR is a traumatic procedure, even in a successful resuscitation, the patient can suffer severe damage to the lungs, heart, or brain, so death will occur hours or days later, or survival will be in the form of an irreversible coma (Purtilo & Cassel, 1981).
Most physicians have had the personal experience of patient survival or improvement despite their initial diagnosis of terminal illness or irreversible coma. Once the patient is put to death by dehydration, it is too late for the doctor to rectify the error.
Dissolved in liquid or pudding, a 10,000-milligram dose of the barbiturate induces a deep, irreversible coma within minutes; death follows soon after.
French television station LCI quoted an anonymous French medical official as saying Arafat was in an "irreversible coma."
The French TV quoted an anonymous French medical source saying Arafat was in an 'irreversible coma' and 'intubated' - a process involving threading a tube down the windpipe to the lungs, often to connect a respirator.
Except for Mozart's La Clemenza di Tito, written after 39 other composers had had a go at the text, Metastasio's verses and their small library of opera seria settings, are now sunk in what one writer aptly called an "irreversible coma."
However, misuse of the drug poses significant health risks, due to the narrow margin between a recreational dose (desired effects) and one leading to unconsciousness or irreversible coma (detrimental effects).
Theses kids are extremely ill and require aggressive and meticulous management to save them from irreversible coma and occasionally death.
According to Ron Wilson, a partner in the Phoenix law firm of Robbins and Green, maintaining life-support systems for a patient in an irreversible coma can cost upward of $1,000 a day.