Level of consciousness, decreased
A decrease in the level of consciousness (LOC), from lethargy to stupor to coma, usually results from a neurologic disorder and may signal a life-threatening complication, such as hemorrhage, trauma, or cerebral edema. However, this sign can also result from a metabolic, GI, musculoskeletal, urologic, or cardiopulmonary disorder; severe nutritional deficiency; the effects of toxins; or drug use. LOC can deteriorate suddenly or gradually and can remain altered temporarily or permanently.
Consciousness is affected by the reticular activating system (RAS), an intricate network of neurons with axons extending from the brain stem, thalamus, and hypothalamus to the cerebral cortex. A disturbance in any part of this integrated system prevents the intercommunication that makes consciousness possible. Loss of consciousness can result from a bilateral cerebral disturbance, an RAS disturbance, or both. Cerebral dysfunction characteristically produces the least dramatic decrease in a patient's LOC. In contrast, dysfunction of the RAS produces the most dramatic decrease in LOC—coma.
The most sensitive indicator of a decreased LOC is a change in the patient's mental status. The Glasgow Coma Scale, which measures a patient's ability to respond to verbal, sensory, and motor stimulation, can be used to quickly evaluate a patient's LOC.
Action stat!
After evaluating the patient's airway, breathing, and circulation, use the Glasgow Coma Scale to quickly determine his LOC and to obtain baseline data. (See Glasgow Coma Scale.) Insert an artificial airway, elevate the head of the bed 30 degrees and, if spinal cord injury has been ruled out, turn the patient's head to the side. Prepare to suction the patient if necessary. You may need to hyperventilate him to reduce carbon dioxide levels and decrease intracranial pressure (ICP). Then determine the rate, rhythm, and depth of spontaneous respirations. Support his breathing with a handheld resuscitation bag, if necessary. If the patient's Glasgow Coma Scale score is less than 9, endotracheal intubation and resuscitation may be necessary.
Continue to monitor the patient's vital signs, being alert for signs of increasing ICP, such as bradycardia and a widening pulse pressure. When his airway, breathing, and circulation are stabilized, perform a neurologic examination.
History and physical examination
Try to obtain history information from the patient, if he's alert, and from his family. Did the patient complain of a headache, dizziness, nausea, vision or hearing disturbances, weakness, fatigue, or other problems before his LOC decreased? Has his family noticed changes in the patient's behavior, personality, memory, or temperament? Also ask about a history of neurologic disease, cancer, or recent trauma or infections; drug and alcohol use; and the development of other signs and symptoms.
Because a decreased LOC can result from a disorder affecting any body system, tailor the remainder of your evaluation according to the patient's associated symptoms.
Medical causes
Adrenal crisis.A decreased LOC, ranging from lethargy to coma, may develop within 8 to 12 hours of the onset of adrenal crisis. Early associated findings include progressive weakness, irritability, anorexia, a headache, nausea and vomiting, diarrhea, abdominal pain, and a fever. Later signs and symptoms include hypotension; a rapid, thready pulse; oliguria; cool, clammy skin; and flaccid extremities. The patient with chronic adrenocortical hypofunction may have hyperpigmented skin and mucous membranes.
Brain abscess.With a brain abscess, decreased LOC varies from drowsiness to deep stupor, depending on the abscess size and site. Early signs and symptoms—a constant intractable headache, nausea, vomiting, and seizures—reflect increasing ICP. Typical later features include ocular disturbances (nystagmus, vision loss, and pupillary inequality) and signs of infection such as a fever. Other findings may include personality changes, confusion, abnormal behavior, dizziness, facial weakness, aphasia, ataxia, tremor, and hemiparesis.
Brain tumor.With a brain tumor, the patient's LOC decreases slowly, from lethargy to coma. He may also experience apathy, behavior changes, memory loss, a decreased attention span, a morning headache, dizziness, vision loss, ataxia, and sensorimotor disturbances. Aphasia and seizures are possible, along with signs of hormonal imbalance, such as fluid retention or amenorrhea. Signs and symptoms vary according to the location and size of the tumor. In later stages, papilledema, vomiting, bradycardia, and a widening pulse pressure also appear. In the final stages, the patient may exhibit decorticate or decerebrate posture.
Cerebral aneurysm (ruptured).Somnolence, confusion and, at times, stupor characterize a moderate cerebral bleed; deep coma occurs with severe bleeding, which can be fatal. The onset is usually abrupt, with a sudden, severe headache and nausea and vomiting. Nuchal rigidity, back and leg pain, a fever, restlessness, irritability, occasional seizures, and blurred vision point to meningeal irritation. The type and severity of other findings vary with the site and severity of the hemorrhage and may include hemiparesis, hemisensory defects, dysphagia, and visual defects.
Diabetic ketoacidosis.Diabetic ketoacidosis produces a rapid decrease in the patient's LOC, ranging from lethargy to coma, commonly preceded by polydipsia, polyphagia, and polyuria. The patient may complain of weakness, anorexia, abdominal pain, nausea, and vomiting. He may also exhibit orthostatic hypotension; a fruity breath odor; Kussmaul's respirations; warm, dry skin; and a rapid, thready pulse. Untreated, this condition invariably leads to coma and death.
Encephalitis.Within 24 to 48 hours after onset of encephalitis, the patient may develop changes in his LOC ranging from lethargy to coma. Other possible findings include an abrupt onset of a fever, a headache, nuchal rigidity, nausea, vomiting, irritability, personality changes, seizures, aphasia, ataxia, hemiparesis, nystagmus, photophobia, myoclonus, and cranial nerve palsies.
Encephalomyelitis (postvaccinal).Postvaccinal encephalomyelitis is a life-threatening disorder that produces rapid deterioration in the patient's LOC, from drowsiness to coma. He also experiences a rapid onset of a fever, a headache, nuchal rigidity, back pain, vomiting, and seizures.
Encephalopathy.With hepatic encephalopathy, signs and symptoms develop in four stages: in the prodromal stage, slight personality changes (disorientation, forgetfulness, slurred speech) and slight tremor; in the impending stage, tremor progressing to asterixis (the hallmark of hepatic encephalopathy), lethargy, aberrant behavior, and apraxia; in the stuporous stage, stupor and hyperventilation, with the patient noisy and abusive when aroused; in the comatose stage, coma with decerebrate posture, hyperactive reflexes, a positive Babinski's reflex, and fetor hepaticus.
With life-threatening hypertensive encephalopathy, the LOC progressively decreases from lethargy to stupor to coma. Besides markedly elevated blood pressure, the patient may experience a severe headache, vomiting, seizures, vision disturbances, transient paralysis and, eventually, Cheyne-Stokes respirations.
With hypoglycemic encephalopathy, the patient's LOC rapidly deteriorates from lethargy to coma. Early signs and symptoms include nervousness, restlessness, agitation, and confusion; hunger; alternate flushing and cold sweats; and a headache, trembling, and palpitations. Blurred vision progresses to motor weakness, hemiplegia, dilated pupils, pallor, a decreased pulse rate, shallow respirations, and seizures. Flaccidity and decerebrate posture appear late.
Depending on its severity, hypoxic encephalopathy produces a sudden or gradual decrease in the LOC, leading to coma and brain death. Initially, the patient appears confused and restless, with cyanosis and increased heart and respiratory rates and blood pressure. Later, his respiratory pattern becomes abnormal, and assessment reveals a decreased pulse, blood pressure, and deep tendon reflexes (DTRs); a positive Babinski's reflex; an absent doll's eye sign; and fixed pupils.
With uremic encephalopathy, the LOC decreases gradually from lethargy to coma. Initially, the patient may appear apathetic, inattentive, confused, and irritable and may complain of a headache, nausea, fatigue, and anorexia. Other findings include vomiting, tremors, edema, papilledema, hypertension, cardiac arrhythmias, dyspnea, crackles, oliguria, and Kussmaul's and Cheyne-Stokes respirations.
Heatstroke.With heatstroke, as body temperature increases, the patient's LOC gradually decreases from lethargy to coma. Early signs and symptoms include malaise, tachycardia, tachypnea, orthostatic hypotension, muscle cramps, rigidity, and syncope. The patient may be irritable, anxious, and dizzy and may report a severe headache. At the onset of heatstroke, the patient's skin is hot, flushed, and diaphoretic with blotchy cyanosis; later, when his fever exceeds 105° F (40.5° C), his skin becomes hot, flushed, and anhidrotic. Pulse and respiratory rate increase markedly, and blood pressure drops precipitously. Other findings include vomiting, diarrhea, dilated pupils, and Cheyne-Stokes respirations.
Hypernatremia.Hypernatremia, life-threatening if acute, causes the patient's LOC to deteriorate from lethargy to coma. He's irritable and exhibits twitches progressing to seizures. Other associated signs and symptoms include a weak, thready pulse; nausea; malaise; a fever; thirst; flushed skin; and dry mucous membranes.
Hyperosmolar hyperglycemic nonketotic syndrome (HHNS).LOC decreases rapidly from lethargy to coma with HHNS. Early findings include polyuria, polydipsia, weight loss, and weakness. Later, the patient may develop hypotension, poor skin turgor, dry skin and mucous membranes, tachycardia, tachypnea, oliguria, and seizures.
Hypokalemia.LOC gradually decreases to lethargy with hypokalemia; coma is rare. Other findings include confusion, nausea, vomiting, diarrhea, and polyuria; weakness, decreased reflexes, and malaise; and dizziness, hypotension, arrhythmias, and abnormal electrocardiogram results.
Hyponatremia.Hyponatremia, life-threatening if acute, produces a decreased LOC in late stages. Early nausea and malaise may progress to behavior changes, confusion, lethargy, incoordination and, eventually, seizures and coma.
Hypothermia.With severe hypothermia (temperature below 90° F [32.2° C]), the patient's LOC decreases from lethargy to coma. DTRs disappear, and ventricular fibrillation occurs, possibly followed by cardiopulmonary arrest. With mild to moderate hypothermia, the patient may experience memory loss and slurred speech as well as shivering, weakness, fatigue, and apathy. Other early signs and symptoms include ataxia, muscle stiffness, and hyperactive DTRs; diuresis; tachycardia and decreased respiratory rate and blood pressure; and cold, pale skin. Later, muscle rigidity and decreased reflexes may develop, along with peripheral cyanosis, bradycardia, arrhythmias, severe hypotension, a decreased respiratory rate with shallow respirations, and oliguria.
Intracerebral hemorrhage.Intracerebral hemorrhage is a life-threatening disorder that produces a rapid, steady loss of consciousness within hours, commonly accompanied by a severe headache, dizziness, nausea, and vomiting. Associated signs and symptoms vary and may include increased blood pressure, irregular respirations, a positive Babinski's reflex, seizures, aphasia, decreased sensations, hemiplegia, decorticate or decerebrate posture, and dilated pupils.
Listeriosis.If listeriosis spreads to the nervous system and causes meningitis, signs and symptoms include a decreased LOC, a fever, a headache, and nuchal rigidity. Early signs and symptoms of listeriosis include a fever, myalgia, abdominal pain, nausea, vomiting, and diarrhea.
Meningitis.Confusion and irritability are expected; however, stupor, coma, and seizures may occur in the patient with severe meningitis. A fever develops early, possibly accompanied by chills. Associated findings include a severe headache, nuchal rigidity, hyperreflexia and, possibly, opisthotonos. The patient exhibits Kernig's and Brudzinski's signs and, possibly, ocular palsies, photophobia, facial weakness, and hearing loss.
Pontine hemorrhage.A sudden, rapid decrease in the patient's LOC to the point of coma occurs within minutes and death within hours of pontine hemorrhage. The patient may also exhibit total paralysis, decerebrate posture, a positive Babinski's reflex, an absent doll's eye sign, and bilateral miosis (however, the pupils remain reactive to light).
Seizure disorders.A complex partial seizure produces a decreased LOC, manifested as a blank stare, purposeless behavior (picking at clothing, wandering, lip smacking or chewing motions), and unintelligible speech. The seizure may be heralded by an aura and followed by several minutes of mental confusion.
An absence seizure usually involves a brief change in the patient's LOC, indicated by blinking or eye rolling, a blank stare, and slight mouth movements.
A generalized tonic-clonic seizure typically begins with a loud cry and sudden loss of consciousness. Muscle spasm alternates with relaxation. Tongue biting, incontinence, labored breathing, apnea, and cyanosis may also occur. Consciousness returns after the seizure, but the patient remains confused and may have difficulty talking. He may complain of drowsiness, fatigue, a headache, muscle aching, and weakness and may fall into a deep sleep.
An atonic seizure produces sudden unconsciousness for a few seconds.
Status epilepticus, rapidly recurring seizures without intervening periods of physiologic recovery and return of consciousness, can be life-threatening.
Shock.A decreased LOC—lethargy progressing to stupor and coma—occurs late in shock. Associated findings include confusion, anxiety, and restlessness; hypotension; tachycardia; a weak pulse with narrowing pulse pressure; dyspnea; oliguria; and cool, clammy skin.
Hypovolemic shock is generally the result of massive or insidious bleeding, either internally or externally. Cardiogenic shock may produce chest pain or arrhythmias and signs of heart failure, such as dyspnea, a cough, edema, jugular vein distention, and weight gain. Septic shock may be accompanied by a high fever and chills. Anaphylactic shock usually involves stridor in response to an allergen.
Stroke.When a stroke occurs, changes in the patient's LOC vary in degree and onset, depending on the lesion's size and location and the presence of edema. A thrombotic stroke usually follows multiple transient ischemic attacks (TIAs) or an episode of atrial fibrillation. Changes in the LOC may be abrupt or take several minutes, hours, or days. An embolic stroke occurs suddenly, and deficits reach their peak almost at once. Deficits associated with a hemorrhagic stroke usually develop over minutes or hours.
Associated findings vary with the stroke type and severity and may include disorientation; intellectual deficits, such as memory loss and poor judgment; personality changes; and emotional lability. Other possible findings include dysarthria, dysphagia, ataxia, aphasia, apraxia, agnosia, unilateral sensorimotor loss, and vision disturbances. In addition, urine retention, incontinence, constipation, a headache, vomiting, and seizures may occur.
Subdural hemorrhage (acute).Acute subdural hemorrhage is a potentially life-threatening disorder in which agitation and confusion are followed by a progressively decreasing LOC from somnolence to coma. The patient may also experience a headache, a fever, unilateral pupil dilation, decreased pulse and respiratory rates, a widening pulse pressure, seizures, hemiparesis, and a positive Babinski's reflex.
Thyroid storm.The patient's LOC decreases suddenly with thyroid storm and can progress to coma. Irritability, restlessness, confusion, and psychotic behavior precede the deterioration. Associated signs and symptoms include tremors and weakness; vision disturbances; tachycardia, arrhythmias, angina, and acute respiratory distress; warm, moist, flushed skin; and vomiting, diarrhea, and a fever of up to 105º F (40.5º C).
TIA.When a TIA occurs, the patient's LOC decreases abruptly (with varying severity) and gradually returns to normal within 24 hours. Site-specific findings may include vision loss, nystagmus, aphasia, dizziness, dysarthria, unilateral hemiparesis or hemiplegia, tinnitus, paresthesia, dysphagia, or staggering or incoordinated gait.
West Nile encephalitis.Signs and symptoms of West Nile encephalitis include fever, headache, and body aches, commonly with a skin rash and swollen lymph glands. More severe infection is marked by high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, occasional seizures, paralysis and, rarely, death.
Other causes
Alcohol.Alcohol use causes varying degrees of sedation, irritability, and incoordination; intoxication commonly causes stupor.
Drugs.Sedation and other degrees of a decreased LOC can result from an overdose of a barbiturate, another central nervous system depressant, or aspirin.
Nursing considerations
▪ Reassess the patient's LOC and neurologic status at least hourly.
▪ Carefully monitor ICP and intake and output.
▪ Ensure airway patency and proper nutrition.
▪ Keep the patient on bed rest and maintain seizure precautions.
▪ Keep emergency resuscitation equipment at the patient's bedside.
▪ Prepare the patient for a computed tomography scan of the head, magnetic resonance imaging of the brain, EEG, and lumbar puncture.
▪ Elevate the head of the bed to at least 30 degrees.
▪ Don't administer an opioid or sedative because either may further decrease the patient's LOC and hinder an accurate, meaningful neurologic examination.
▪ Talk to the patient even if he appears comatose; your voice may help reorient him to reality.
Patient teaching
▪ Explain the underlying cause of decreased LOC and its treatments and procedures to the patient and his family.
▪ Teach them about safety and seizure precautions.
▪ Provide referrals to sources of support.
▪ Discuss quality of life issues, if appropriate.
Pictures
Book Source Details
- Book Title: Nursing: Interpreting Signs and Symptoms
- Author(s): Springhouse
- Year of Publication: 2007
- Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.
Other Book Chapters Related to Drowsiness
Read excerpts from these other book chapters related to Drowsiness:
Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2008 Williams & Wilkins.
More About Causes of Drowsiness
» Next page: Muscle weakness (Nursing: Interpreting Signs and Symptoms)
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