irreversible coma


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coma

 [ko´mah]
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.

irreversible coma

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.

coma

a state of unconsciousness from which the patient cannot be aroused, even by powerful stimuli.

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
results from reversible biochemical abnormalities of the cerebrum, caused by elevated blood levels of toxic substances such as ammonia, amino acids, short-chain fatty acids and beta hydroxylated biogenic amines that accumulate in severe liver disease. See also hepatic encephalopathy.
irreversible coma
coma in which for a period of 24 hours there is complete nonreceptivity and nonresponsivity even to the most intensely painful stimuli, no spontaneous movement or breathing, absence of elicitable reflexes, and a flat electroencephalogram. Called also brain death.
myxedema coma
the mental stupor caused by severe hypothyroidism; seen most often in Doberman pinchers, it is associated with hypoventilation, hypothermia, hypotension and bradycardia. Death may occur.
References in periodicals archive ?
Little did the court know that the judgment ordering the removal of all life support systems would, in fact, draw national attention to the little girl who defied the medical experts who had opined that she was in an irreversible coma and in a PVS.
At about the same time, in 1968, medical researchers published the Harvard Criteria for Irreversible Coma.
The problem is that he goes into an irreversible coma, leaving police helpless to find his latest victim - that is, of course, unless Lopez's character can root around his mind to find the location of the cell.
The previous state-governed, over-centralized system, which was proved to be hopelessly inefficient, is now in a state of irreversible coma.
Second, the concept of 'terminal condition' would be expanded to include patients who, in the written determination of two physicians, "have no reasonable probability of recovery from an irreversible coma or persistent vegetative state.
Nutrition is customarily provided as an element of comfort care, and hydration is expected to be given until the end, except when there is cerebral death or irreversible coma.
Unfortunately, enormous conceptual and scientific confusion persists concerning the characteristics of these new syndromes, which include brain death (whole brain death), persistent vegetative state (PVS), permanent unconsciousness, coma, dementia, irreversible coma, chronic and irreversible coma, neocortical death, and locked-in syndrome.
In another, an impaired anesthesiologist on drugs was finally exposed after causing two women to lapse into irreversible comas.
THE NETHERLANDS--Health officials in the Netherlands are considering guidelines for euthanasia that doctors could follow for terminally ill patients with "no free will," such as children, the severely mentally retarded, and patients in irreversible comas.
At least four people using it for this purpose have died in irreversible comas since 1995.
The hospital also asked several smaller hospitals throughout the country to notify it of patients in irreversible comas so that it could negotiate with their families for buying organs, Supachai said.