coma (ko´ma)

1. A state of profound unconsciousness from which one cannot be roused; may be due to the action of an ingested toxic substance or of one formed in the body, to trauma, or to disease. 2. An aberration of spherical lenses; occurring in cases of oblique incidence (e.g., the image of a point becomes comet-shaped). [G. kome, hair] 3. coma aberration [G. koma, deep sleep, trance]
c. carcinomato´sum c. occurring in the final stage of cancerous cachexia.
delayed c. after hypoxia c. that develops a few days to 3 weeks after an acute hypoxic insult; the latter was usually severe enough to cause an initial bout of coma, which cleared, and was followed by a transient interval of apparent normality.severe postanoxic encephalopathy;
diabetic c. c. that develops in severe and inadequately treated cases of diabetes mellitus and is commonly fatal, unless appropriate therapy is instituted promptly; results from reduced oxidative metabolism of the central nervous system that, in turn, stems from severe ketoacidosis and possibly also from the histotoxic action of the ketone bodies and disturbances in water and electrolyte balance.Kussmaul's c;
hepatic c. c. that occurs with advanced hepatic insufficiency and portal-systemic shunts, caused by elevated blood ammonia levels; characteristic findings include asterixis in the precoma stage and paroxysms of bilaterally synchronous triphasic waves on EEG examination.
hyperosmolar (hyperglycemic) nonketotic c. (hI´per-os-mo-lar) a complication seen in diabetes mellitus in which very marked hyperglycemia occurs (such as levels over 800 mg/dL) causing osmotic shifts in water in brain cells and resulting in coma. It can be fatal or lead to permanent neurologic damage. Ketoacidosis does not occur in these cases.nonketotic hyperglycemia;
hypoglycemic c. a metabolic encephalopathy caused by hypoglycemia; usually seen in diabetics, and due to exogenous insulin excess.
hypoventilation c. coma seen with advanced lung failure and resultant hypoventilation.CO2 narcosis, hypoxic-hypercarbic encephalopathy, pulmonary encephalopathy;
Kussmaul's c. diabetic c
metabolic c. coma resulting from diffuse failure of neuronal metabolism, caused by such abnormalities as intrinsic disorders of neuron or glial cell metabolism, or extracerebral disorders that produce intoxication or electrolyte imbalances.
thyrotoxic c. c. preceding death in severe hyperthyroidism, as in thyroid storm or thyrotoxic crisis.
trance c. lethargic hypnosis
uremic c. a metabolic encephalopathy caused by renal failure.


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