Loss of consciousness

Acute benzene poisoning results in CNS depression and is characterized by an initial euphoria followed by staggered gait, stupor, coma, and convulsions. Exposure to approximately 4000 ppm benzene results in complete loss of consciousness. Insomnia, agitation, headache, nausea, and drowsiness may persist for weeks after exposure (126). Continued inhalation of benzene to the point of euphoria has caused irreversible encephalopathy with tremulousness, emotional lability, and diffuse cerebral atrophy (125). In deaths arising from acute exposure, respiratory tract infection, hypo- and hyperplasia of sternal bone marrow, congested kidneys, and cerebral edema have been found at autopsy. 

Ingestion of chloroform is followed immediately by a severe burning in the mouth and throat, pain in the chest and abdomen, and vomiting. Loss of consciousness and Hver injury may foUow depending on the amount swallowed. The tendency of chloroform to produce Hver injury is significantly augmented in alcohoHcs and persons with nutritional deficiencies. 

CNS DEPRESSANT Substanccs, e.g. anaesthetics and narcotics, which depress the activity of the central nervous system. Symptoms following exposure include headache, dizziness, loss of consciousness, respiratory or cardiac depression, death. 

OXYGEN DEFICIENCY Depletion of oxygen content in an atmosphere to below the normal 21%. Exposure to <18% must not be permitted. Concentrations 6% to 10% oxygen can lead to loss of consciousness. 

Increased respiration, slight diminution of coordination Loss of ability to think clearly Loss of consciousness, death... 

Anesthetic, general. A compound that, when given systemically, causes a reversible loss of consciousness sufficient to allow surgical procedures. 

Epilepsy, grand mal. A disorder resulting in occasional loss of consciousness and violent uncontrolled contraction of the muscles. 

Ethanol is classified for medical purposes as a central nervous system (CNS) depressant. Its effects—that is, being drunk—resemble the human response to anesthetics. There is an initial excitability and increase in sociable behavior, but this results from depression of inhibition rather than from stimulation. At a blood alcohol concentration of 0.1% to 0.3%, motor coordination is affected, accompanied by loss of balance, slurred speech, and amnesia. When blood alcohol concentration rises to 0.3% to 0.4%, nausea and loss of consciousness occur. Above 0.6%, spontaneous respiration and cardiovascular regulation are affected, ultimately leading to death. The LD50 of ethanol is 10.6 g/kg (Chapter 1 Focus On). 

Glucose is also called blood sugar. It is absorbed readily into the bloodstream and is normally found there at concentrations ranging from 0.004 to 0.008 mol/L. If the concentration of glucose drops below 0.003 M, a condition called hypoglycemia is created, with symptoms ranging from nervousness to loss of consciousness. If the glucose level rises above 0.01 M, as can easily happen with diabetics, it is excreted in the urine. 

Primary generalized seizures are also heterogeneous with respect to their clinical features. Such seizures can impose as absence epilepsy, which is characterized by a brief interruption of consciousness due to highly synchronized neuronal activity involving thalamocortical networks without increases in neuronal firing rate. On the other hand, tonic-clonic convulsions with loss of consciousness are often also primarily generalized. 

The first dose effect may be minimized by decreasing the initial dose and administering the dose at bedtime The dosage can then be slowly increased every 2 weeks until a full therapeutic effect is achieved. If die patient experiences syncope, die nurse places die patient in a recumbent position and treats supportively. This effect is self-limiting and in most cases does not recur after the initial period of tiierapy. Light-headedness and dizziness are more common tiian loss of consciousness. The section below discusses these effects and provides interventions for management. 

Generalized seizures include absence, myoclonic, and tonic-clonic. Manifestations of a generalized tonic-clonic seizure include alternate contraction (tonic phase) and relaxation (clonic phase) of muscles, a loss of consciousness, and abnormal behavior. Myoclonic seizures involve sudden, forceful contractions involving the musculature of the trunk, neck, and extremities. Absence seizures, previously referred to as petit mal seizures, are seizures characterized by a brief loss of consciousness during which physical activity ceases. The seizures typically last a few seconds, occur many times a day, and may go unnoticed by others. 

Hyperglycemia is the most common metabolic complication. A too rapid infuson of amino add-carbohydrate mixtures may result in hyperglycemia, glycosuria, mental confuson, and loss of consciousness Blood glucose levels may be obtained every 4 to 6 hours to monitor for hyperglycemia and guide the dosage of dextrose and insulin (if required). To minimize these complications the primary health care provider may decrease the rate of administration, reduce the dextrose concentration, or administer insulin. 

Phencyclidine (l-[l-phenylcyclohexyl] piperidine, PCP) was originally developed as an intravenous anesthetic in the 1950s. Used for this indication, it causes a trance-like state without loss of consciousness and was hence classified as a dissociative anesthetic. However, it was soon withdrawn from human use because it produced unpleasant hallucinations, agitation, and delirium. The product was later used in veterinary medicine. Ketamine, a chemically closely related substance, was developed to replace PCP and is stiU in use as a dissociative anesthetic in children. Ketamine is less potent than PCP, and its effects are of shorter duration. However, it may also cause hallucinations (see the section on ketamine in Chapter 7, Club Drugs ). Much of the ketamine sold on the street (special K, cat Valium) has been diverted from veterinarians offices. 

Miotto and colleagues (2001) surveyed 42 recreational users of GHB and found that 66% reported episodes of unpredictable loss of consciousness and 26% had overdosed. Forty-five percent of daily users had experienced frequent amnesia during or after use of the drug, suggestive of blackouts typically attributed to severe alcohol abuse. The rate of adverse events was greater... 

Children are affected by methyl parathion in the same manner as adults. Exposure to high levels of methyl parathion, even for short periods, may result in changes in the nervous system, leading to headaches, dizziness, confusion, blurred vision, difficulty breathing, vomiting, diarrhea, loss of consciousness, and death (see also Section 1.5 for a more complete description of how methyl parathion affects human health). It is not known whether children are more sensitive to the effects of methyl parathion than adults. There is some indication that young rats may be more sensitive than adults to nervous system effects. 

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