(kō-lŭm′nă) pl. columnae [L.] A column or pillar.
(kŏ-lŭm′năr) 1. In anatomy, shaped like a column or pillar. 2. In histology, composed of long, narrow, cylindrical epithelial cells.
[L. cum, with] Prefix meaning together or with. Com- remains com- before vowels and b, m, and p; it becomes col- before l; cor- before r; and con- before all other sounds. SEE: syn-.
(kō′mă) [Gr. kōma, a deep sleep] A state of unconsciousness from which one cannot be aroused. Coma is the most severe of the alterations of consciousness. It differs from sleep in that comatose patients will not awaken with stimulation. It differs from lethargy, drowsiness, or stupor (states in which patients are slow to respond) in that comatose patients are completely unresponsive. Finally, it differs from delirium, confusion, or hallucinosis (states in which patients' sense of reality is distorted and expressions are bizarre) in that comatose patients cannot express themselves at all. SEE: Glasgow Coma Scale.
ETIOLOGY: Two thirds of the time, coma results from diffuse brain injury or intoxication, such as may be caused by drug overdose, poisoning, hypoglycemia, uremia, liver failure, infection, or closed-head trauma. In about one third of cases, coma results from intracranial lesions, such as massive strokes, brain tumors, or abscesses. For these focal injuries to depress consciousness, the lesion must result in compression or injury to the brain's reticular activating system (the network of cells responsible for arousal). Rarely, coma is feigned by patients with psychiatric illnesses.
TREATMENT: The airway, breathing, and circulation are supported. The cervical spine is protected if there is any question of traumatic injury to the head and neck. A rapid physical examination is performed to determine whether the patient has focal neurological deficits. Simultaneously, intravenous dextrose, naloxone, and thiamine are given (to try to reverse narcotic overdose or diabetic coma). If the examination reveals focal findings, an intracranial lesion may be present and should be quickly diagnosed (with brain scans) and treated, e.g., with neurosurgery, if appropriate. If the patient is neurologically nonfocal, treatment focuses on metabolic support, the administration of antidotes for any proven intoxications, and treatment for infections. Seizures, if present, should be promptly controlled with anticonvulsants. Blood sugar levels should be tightly controlled (between 80 and 110 mg/dL). Fevers should be suppressed with antipyretics. Acid-base disturbances should be corrected.
If there is a question whether the coma is due to an overdose of insulin or to hypoglycemia, it is crucial to give glucose intravenously. Administration of naloxone is also standard care.
PATIENT CARE: A patent airway is maintained. If neck trauma is suspected, e.g., if the patient was found on the floor, the patient should not be ...